• 牛客网语法篇之Java入门

    JAVA1 类型转换

    1. import java.util.Scanner;
    2.  
    3. public class Main {
    4.     public static void main(String[] args) {
    5.         Scanner scanner = new Scanner(System.in);
    6.         double d = scanner.nextDouble();
    7.         System.out.println(Main.typeConversion(d));
    8.     }
    9.     public static int typeConversion(double d){
    10.  
    11.         //write your code here......
    12.         return (int)d;
    13.  
    14.     }
    15. }

    JAVA2 简单运算

    1. import java.util.Scanner;
    2.  
    3. public class Main {
    4.     public static void main(String[] args) {
    5.         Scanner scanner = new Scanner(System.in);
    6.         int a = scanner.nextInt();
    7.         int b = scanner.nextInt();
    8.         scanner.close();
    9.  
    10.         //write your code here......
    11.         int sum = a + b;
    12.         int difference = a > b ? a - b : b - a;
    13.         int product = a * b;
    14.         int quotient = a > b ? a / b : b / a;
    15.         int module = a > b ? a % b : b % a;
    16.         System.out.println(sum + " " + difference + " " + product + " " + quotient + " " + module);
    17.  
    18.     }
    19. }

    JAVA3 四舍五入

    1. import java.util.Scanner;
    2.  
    3. public class Main {
    4.     public static void main(String[] args) {
    5.         Scanner scanner = new Scanner(System.in);
    6.         double d= scanner.nextDouble();
    7.  
    8.         //write your code here......
    9.         int i = (int)(d * 10) % 10 >= 5 ? (int)d + 1 : (int)d;
    10.  
    11.         System.out.println(i);
    12.     }
    13. }

    JAVA4 交换变量值

    1. import java.util.Scanner;
    2.  
    3. public class Main {
    4.     public static void main(String[] args) {
    5.         Scanner scanner = new Scanner(System.in);
    6.         int a = scanner.nextInt();
    7.         int b = scanner.nextInt();
    8.  
    9.         //write your code here.......
    10.         int temp = a;
    11.         a = b;
    12.         b = temp;
    13.         
    14.  
    15.         System.out.println(a+" "+b);
    16.     }
    17. }

    JAVA5 计算商场折扣

    1. import java.util.*;
    2.  
    3. public class Main {
    4.     public static void main(String[] args) {
    5.         Scanner console = new Scanner(System.in);
    6.         int price = console.nextInt();
    7.         int cost = 0;
    8.  
    9.         //write your code here......
    10.         if (price < 100) {
    11.             cost = price;
    12.         } else if (price < 500) {
    13.             cost = (int)(price * 0.9);
    14.         } else if (price < 2000) {
    15.             cost = (int)(price * 0.8);
    16.         } else if (price < 5000) {
    17.             cost = (int)(price * 0.7);
    18.         } else {
    19.             cost = (int)(price * 0.6);
    20.         }
    21.  
    22.         System.out.println(cost);
    23.     }
    24. }

    JAVA6 判断体重指数

    1. import java.util.Scanner;
    2.  
    3. public class Main {
    4.     public static void main(String[] args) {
    5.         Scanner scanner = new Scanner(System.in);
    6.         double height = scanner.nextDouble();
    7.         double weight = scanner.nextDouble();
    8.  
    9.         //write your code here......
    10.         double bmi = weight / (height * height);
    11.         if (bmi < 18.5) {
    12.             System.out.println("偏瘦");
    13.         } else if (bmi < 20.9) {
    14.             System.out.println("苗条");
    15.         } else if (bmi < 24.9) {
    16.             System.out.println("适中");
    17.         } else {
    18.             System.out.println("偏胖");
    19.         }
    20.  
    21.     }
    22. }

    JAVA7 判断学生成绩等级

    1. import java.util.Scanner;
    2.  
    3. public class Main {
    4.     public static void main(String[] args) {
    5.         Scanner scanner = new Scanner(System.in);
    6.         String grade =scanner.next();
    7.  
    8.         //write your code here......
    9.         switch (grade) {
    10.             case "A":
    11.                 System.out.println("优秀");
    12.                 break;
    13.             case "B":
    14.                 System.out.println("良好");
    15.                 break;
    16.             case "C":
    17.                 System.out.println("及格");
    18.                 break;
    19.             case "D":
    20.                 System.out.println("不及格");
    21.                 break;
    22.             default:
    23.                 System.out.println("未知等级");
    24.         }
    25.  
    26.     }
    27. }

    JAVA8 邮箱验证

    1. import java.util.Scanner;
    2.  
    3. public class Main {
    4.     public static void main(String[] args) {
    5.  
    6.         Scanner scanner = new Scanner(System.in);
    7.         String str = scanner.next();
    8.         String emailMatcher="[a-zA-Z0-9]+@[a-zA-Z0-9]+\\.[a-zA-Z0-9]+";
    9.  
    10.         //write your code here......
    11.         if (str.matches(emailMatcher)) {
    12.             System.out.println("邮箱格式合法");
    13.         } else {
    14.             System.out.println("邮箱格式不合法");
    15.         }
    16.  
    17.     }
    18. }

    JAVA9 数列求和

    1. public class Main {
    2.     public static void main(String[] args) {
    3.  
    4.         //write your code here........
    5.         long sum = 0;
    6.         for (long i = 9; i <= 9999999999L; i = i * 10 + 9) {
    7.             sum += i;
    8.         }
    9.         System.out.println(sum);
    10.  
    11.     }
    12. }

    JAVA10 统计输入正数个数

    1. import java.util.*;
    2.  
    3. public class Main {
    4.     public static void main(String[] args) {
    5.         int count = 0;
    6.         Scanner scanner = new Scanner(System.in);
    7.  
    8.         //write your code here......
    9.         while (scanner.nextInt() > 0) {
    10.             count++;
    11.         }
    12.         System.out.println(count);
    13.  
    14.     }
    15. }

    JAVA11 求最小公倍数

    1. import java.util.*;
    2.  
    3. public class Main {
    4.     public static void main(String[] args) {
    5.         Scanner console = new Scanner(System.in);
    6.         int m = console.nextInt();
    7.         int n = console.nextInt();
    8.         int result = getCM(m, n);
    9.         System.out.println(result);
    10.     }
    11.  
    12.     public static int getCM(int m, int n){
    13.  
    14.         //write your code here......
    15.         int a = m > n ? m : n;
    16.         int b = m > n ? n : m;
    17.         
    18.         while (b > 0) {
    19.             int temp = a % b;
    20.             a = b;
    21.             b = temp;
    22.         }
    23.         
    24.         return m * n / a;
    25.  
    26.     }
    27. }

    JAVA12 小球走过路程计算

    1. import java.util.Scanner;
    2.  
    3. public class Main {
    4.     public static void main(String[] args) {
    5.         Scanner scanner=new Scanner(System.in);
    6.         float h=scanner.nextFloat();
    7.         int n =scanner.nextInt();
    8.  
    9.         //write your code here......
    10.         float sum = h;
    11.         h /= 2;
    12.         for (int i = 1; i < n; ++i) {
    13.             sum += h * 2;
    14.             h /= 2;
    15.         }
    16.         System.out.println(String.format("%.3f", h)+" "+String.format("%.3f", sum));
    17.  
    18.         //输出格式为：System.out.println(String.format("%.3f", h)+" "+String.format("%.3f", sum));
    19.         
    20.  
    21.     }
    22. }

    JAVA13 求平均数

    1. import java.util.Scanner;
    2.  
    3. public class Main {
    4.  
    5.     public static void main(String[] args) {
    6.         Scanner scan = new Scanner(System.in);
    7.  
    8.         //write your code here......
    9.         int number;
    10.         double avg = 0;
    11.         int count = 0;
    12.         while ((number = scan.nextInt()) != -1) {
    13.             avg += number;
    14.             count++;
    15.         }
    16.         avg /= count;
    17.  
    18.         //输出格式为：System.out.println(String.format("%.2f",avg));
    19.         System.out.println(String.format("%.2f",avg));
    20.  
    21.     }
    22. }

    JAVA14 判断质数

    1. import java.util.Scanner;
    2.  
    3. public class Main {
    4.     public static void main(String[] args) {
    5.         Main main = new Main();
    6.         Scanner scan = new Scanner(System.in);
    7.         int number = scan.nextInt();
    8.         System.out.println(main.isPrimeNumber(number));
    9.     }
    10.  
    11.     public Boolean isPrimeNumber(int number) {
    12.  
    13.         //write your code here......
    14.         for (int i = 2; i * i <= number; i++) {
    15.             if (number % i == 0) {
    16.                 return false;
    17.             }
    18.         }
    19.         return true;
    20.  
    21.     }
    22. }

    JAVA15 计算整数位数

    1. import java.util.Scanner;
    2.  
    3. public class Main {
    4.     public static void main(String[] args) {
    5.         Scanner scan = new Scanner(System.in);
    6.         int num = scan.nextInt();
    7.         scan.close();
    8.  
    9.         //write code here......
    10.         if (num > 0) {
    11.             int numOfDigits = 0;
    12.             while (num > 0) {
    13.                 numOfDigits++;
    14.                 num /= 10;
    15.             }
    16.             System.out.println(numOfDigits);
    17.         } else {
    18.             System.out.println(num);
    19.         }
    20.  
    21.     }
    22. }

    JAVA16 数组遍历

    1. import java.util.Scanner;
    2.  
    3. public class Main {
    4.     public static void main(String[] args) {
    5.         int[] ary = new int[6];
    6.         int max;
    7.         int min;
    8.         Scanner scanner = new Scanner(System.in);
    9.      	for (int i = 0; i 
    10.             ary[i]=scanner.nextInt();
    11.         }
    12.  
    13.         //write your code here......
    14.         max = ary[0];
    15.         min = ary[0];
    16.         for (int i = 1; i < ary.length; i++) {
    17.             max = max < ary[i] ? ary[i] : max;
    18.             min = min > ary[i] ? ary[i] : min;
    19.         }
    20.  
    21.         System.out.println(max+" "+min);
    22.     }
    23. }

    JAVA17 数组倒转

    1. import java.util.Arrays;
    2. import java.util.Scanner;
    3.  
    4. public class Main {
    5.     public static void main(String[] args) {
    6.         int[] arr = new int[6];
    7.         Scanner scanner = new Scanner(System.in);
    8.         for (int i = 0; i < arr.length; i++) {
    9.             arr[i] = scanner.nextInt();
    10.         }
    11.         System.out.println(Arrays.toString(arr));
    12.  
    13.         //write your code here......
    14.         for (int i = 0, j = arr.length - 1; i < j; i++, j--) {
    15.             int temp = arr[i];
    16.             arr[i] = arr[j];
    17.             arr[j] = temp;
    18.         }
    19.         
    20.  
    21.         System.out.println(Arrays.toString(arr));
    22.     }
    23. }

    JAVA18 二维数组求和

    1. public class Main {
    2.     public static void main(String[] args) {
    3.         int[][]  arr = {{11,33,55},{22,44,66,88},{131,214,315,146},{928,827,726,625},{424,525}};
    4.         int sum=add(arr);
    5.         System.out.println(sum);
    6.     }
    7.  
    8.     public static int add(int[][] arr) {
    9.         int sum=0;
    10.  
    11.         //write your code here......
    12.         for (int i = 0; i < arr.length; i++) {
    13.             for (int j = 0; j < arr[i].length; j++) {
    14.                 sum += arr[i][j];
    15.             }
    16.         }
    17.  
    18.         return sum;
    19.     }
    20. }

    JAVA19 修改Data类的定义

    1. import java.util.Scanner;
    2.  
    3. public class Main {
    4.  
    5.     public static void main(String[] args) {
    6.         Scanner scanner = new Scanner(System.in);
    7.         while (scanner.hasNextInt()) {
    8.             int x = scanner.nextInt();
    9.             int y = scanner.nextInt();
    10.             Data data = new Data(x, y);
    11.             System.out.println(data.getX() + data.getY());
    12.         }
    13.     }
    14.  
    15. }
    16.  
    17. class Data {
    18.  
    19.     private int x;
    20.     private int y;
    21.  
    22.     Data(int x, int y) {
    23.         this.x = x;
    24.         this.y = y;
    25.     }
    26.  
    27.     public int getX() {
    28.         return x;
    29.     }
    30.  
    31.     public int getY() {
    32.         return y;
    33.     }
    34.  
    35. }

    JAVA20 验证年龄

    1. import java.util.Scanner;
    2.  
    3. public class Main {
    4.  
    5.     public static void main(String[] args) {
    6.         Person p = new Person();
    7.         Scanner scanner = new Scanner(System.in);
    8.         while (scanner.hasNextInt()) {
    9.             int age = scanner.nextInt();
    10.             p.setAge(age);
    11.             System.out.println(p.getAge());
    12.         }
    13.     }
    14.  
    15. }
    16.  
    17. class Person {
    18.  
    19.     private int age;
    20.  
    21.     //write your code here......
    22.     public void setAge(int age) {
    23.         this.age = age;
    24.     }
    25.     
    26.     public int getAge() {
    27.         if (age < 0) {
    28.             return 0;
    29.         } else if (age > 200) {
    30.             return 200;
    31.         } else {
    32.             return age;
    33.         }
    34.     }
    35.  
    36. }

    JAVA21 补全构造方法

    1. import java.util.Scanner;
    2.  
    3. public class Main {
    4.  
    5.     public static void main(String[] args) {
    6.         Scanner scanner = new Scanner(System.in);
    7.         while (scanner.hasNextInt()) {
    8.             int x = scanner.nextInt();
    9.             int y = scanner.nextInt();
    10.             int z = scanner.nextInt();
    11.             Sub sub = new Sub(x, y, z);
    12.             System.out.println(sub.calculate());
    13.         }
    14.     }
    15.  
    16. }
    17.  
    18. class Base {
    19.  
    20.     private int x;
    21.     private int y;
    22.  
    23.     public Base(int x, int y) {
    24.         this.x = x;
    25.         this.y = y;
    26.     }
    27.  
    28.     public int getX() {
    29.         return x;
    30.     }
    31.  
    32.     public int getY() {
    33.         return y;
    34.     }
    35.  
    36. }
    37.  
    38. class Sub extends Base {
    39.  
    40.     private int z;
    41.  
    42.     public Sub(int x, int y, int z) {
    43.  
    44.         //write your code here
    45.         super(x, y);
    46.         this.z = z;
    47.  
    48.     }
    49.  
    50.     public int getZ() {
    51.         return z;
    52.     }
    53.  
    54.     public int calculate() {
    55.         return super.getX() * super.getY() * this.getZ();
    56.     }
    57.  
    58. }

    JAVA22 重写计算逻辑

    1. import java.util.Scanner;
    2.  
    3. public class Main {
    4.  
    5.     public static void main(String[] args) {
    6.         Scanner scanner = new Scanner(System.in);
    7.         while (scanner.hasNextInt()) {
    8.             int x = scanner.nextInt();
    9.             int y = scanner.nextInt();
    10.             Sub sub = new Sub(x, y);
    11.             sub.calculate();
    12.         }
    13.     }
    14.  
    15. }
    16.  
    17. class Base {
    18.  
    19.     private int x;
    20.     private int y;
    21.  
    22.     public Base(int x, int y) {
    23.         this.x = x;
    24.         this.y = y;
    25.     }
    26.  
    27.     public int getX() {
    28.         return x;
    29.     }
    30.  
    31.     public int getY() {
    32.         return y;
    33.     }
    34.  
    35.     public void calculate() {
    36.         System.out.println(getX() * getY());
    37.     }
    38.  
    39. }
    40.  
    41. class Sub extends Base {
    42.  
    43.     //write your code here......
    44.     public Sub(int x, int y) {
    45.         super(x, y);
    46.     }
    47.     
    48.     public void calculate() {
    49.         System.out.println(getY() == 0 ? "Error" : getX() / getY());
    50.     }
    51.  
    52. }

    JAVA23 定义打印方法

    1. import java.util.Scanner;
    2.  
    3. public class Main {
    4.  
    5.     public static void main(String[] args) throws Exception {
    6.         Scanner scanner = new Scanner(System.in);
    7.         while (scanner.hasNext()) {
    8.             String className = scanner.next();
    9.             // print就是需要你定义的方法
    10.             print(Class.forName(className).newInstance());
    11.         }
    12.     }
    13.  
    14.     //write your code here......
    15.     private static void print(Object clazz) {
    16.         System.out.println(clazz.toString());
    17.     }
    18.  
    19. }
    20.  
    21. class First {
    22.     public String toString() {
    23.         return "First";
    24.     }
    25. }
    26.  
    27. class Second {
    28.     public String toString() {
    29.         return "Second";
    30.     }
    31. }
    32.  
    33. class Third {
    34.     public String toString() {
    35.         return "Third";
    36.     }
    37. }

    JAVA24 类型判断

    1. import java.util.Scanner;
    2.  
    3. public class Main {
    4.  
    5.     public static void main(String[] args) throws Exception {
    6.         Scanner scanner = new Scanner(System.in);
    7.         while (scanner.hasNext()) {
    8.             String className = scanner.next();
    9.             Base obj = (Base) Class.forName(className).newInstance();
    10.             System.out.println(getClassName(obj));
    11.         }
    12.     }
    13.  
    14.     public static String getClassName(Base obj) {
    15.  
    16.         //write your code here......
    17.         return obj.getClass().getName();
    18.  
    19.     }
    20.  
    21. }
    22.  
    23. class Base {
    24.  
    25. }
    26.  
    27. class Sub1 extends Base {
    28.  
    29. }
    30.  
    31. class Sub2 extends Base {
    32.  
    33. }

    JAVA25 实现抽象方法

    1. import java.util.Scanner;
    2.  
    3. public class Main {
    4.  
    5.     public static void main(String[] args) {
    6.         // Sub是需要你定义的子类
    7.         Base base = new Sub();
    8.  
    9.         Scanner scanner = new Scanner(System.in);
    10.         while (scanner.hasNextInt()) {
    11.             int x = scanner.nextInt();
    12.             int y = scanner.nextInt();
    13.             base.setX(x);
    14.             base.setY(y);
    15.             System.out.println(base.calculate());
    16.         }
    17.     }
    18.  
    19. }
    20.  
    21. abstract class Base {
    22.  
    23.     private int x;
    24.     private int y;
    25.  
    26.     public int getX() {
    27.         return x;
    28.     }
    29.  
    30.     public void setX(int x) {
    31.         this.x = x;
    32.     }
    33.  
    34.     public int getY() {
    35.         return y;
    36.     }
    37.  
    38.     public void setY(int y) {
    39.         this.y = y;
    40.     }
    41.  
    42.     public int calculate() {
    43.         if (avg() == 0) {
    44.             return 0;
    45.         } else {
    46.             return sum() / avg();
    47.         }
    48.     }
    49.  
    50.     /**
    51.      * 返回x和y的和
    52.      */
    53.     public abstract int sum();
    54.  
    55.     /**
    56.      * 返回x和y的平均值
    57.      */
    58.     public abstract int avg();
    59.  
    60. }
    61.  
    62. class Sub extends Base {
    63.  
    64.     //write your code here......
    65.     public int sum() {
    66.         return getX() + getY();
    67.     }
    68.     
    69.     public int avg() {
    70.         return (getX() + getY()) / 2;
    71.     }
    72.  
    73. }

    JAVA26 实现接口

    1. import java.util.Scanner;
    2.  
    3. public class Main {
    4.  
    5.     public static void main(String[] args) {
    6.         Comparator comparator = new ComparatorImpl();
    7.  
    8.         Scanner scanner = new Scanner(System.in);
    9.         while (scanner.hasNextInt()) {
    10.             int x = scanner.nextInt();
    11.             int y = scanner.nextInt();
    12.             System.out.println(comparator.max(x, y));
    13.         }
    14.     }
    15.  
    16. }
    17.  
    18. interface Comparator {
    19.     /**
    20.      * 返回两个整数中的最大值
    21.      */
    22.     int max(int x, int y);
    23. }
    24.  
    25. //write your code here......
    26. class ComparatorImpl implements Comparator {
    27.     public int max(int x, int y) {
    28.         return x > y ? x : y;
    29.     }
    30. }

    JAVA27 重写父类方法

    1. import java.util.Scanner;
    2.  
    3. public class Main {
    4.  
    5.     public static void main(String[] args) {
    6.         Scanner scanner = new Scanner(System.in);
    7.         while (scanner.hasNextInt()) {
    8.             int x = scanner.nextInt();
    9.             int y = scanner.nextInt();
    10.             Sub sub = new Sub(x, y);
    11.             System.out.println(sub.sum());
    12.         }
    13.     }
    14.  
    15. }
    16.  
    17. class Base {
    18.  
    19.     private int x;
    20.     private int y;
    21.  
    22.     public Base(int x, int y) {
    23.         this.x = x;
    24.         this.y = y;
    25.     }
    26.  
    27.     public int getX() {
    28.         return x;
    29.     }
    30.  
    31.     public final int getY() {
    32.         return y;
    33.     }
    34.  
    35.     public final int sum() {
    36.         return getX() + getY();
    37.     }
    38.  
    39. }
    40.  
    41. class Sub extends Base {
    42.  
    43.     public Sub(int x, int y) {
    44.         super(x, y);
    45.     }
    46.  
    47.     //write your code here......
    48.     public int getX() {
    49.         return 10 * super.getX();
    50.     }
    51. }

    JAVA28 创建单例对象

    1. public class Main {
    2.  
    3.     public static void main(String[] args) {
    4.         Singleton s1 = Singleton.getInstance();
    5.         Singleton s2 = Singleton.getInstance();
    6.         System.out.println(s1 == s2);
    7.     }
    8.  
    9. }
    10.  
    11. class Singleton {
    12.  
    13.     private static Singleton instance;
    14.  
    15.     private Singleton() {
    16.  
    17.     }
    18.  
    19.     //write your code here......
    20.     public static Singleton getInstance() {
    21.         return instance;
    22.     }
    23.  
    24. }

    JAVA29 动态字符串

    1. import java.util.Scanner;
    2.  
    3. public class Main {
    4.     public static void main(String[] args) {
    5.         Scanner scanner = new Scanner(System.in);
    6.         String str = scanner.next();
    7.  
    8.         //write your code here......
    9.         StringBuilder modifiedStr = new StringBuilder();
    10.         int ptr = str.length();
    11.         modifiedStr.append(str, Math.max(ptr - 3, 0), ptr);
    12.         ptr -= 3;
    13.         while (ptr > 0) {
    14.             modifiedStr.insert(0, str.substring(Math.max(ptr - 3, 0), ptr) + ",");
    15.             ptr -= 3;
    16.         }
    17.  
    18.         System.out.println(modifiedStr.toString());
    19.  
    20.     }
    21. }

    JAVA30 统计字符串中字母出现次数

    1. import java.util.Scanner;
    2.  
    3. public class Main {
    4.     public static void main(String[] args) {
    5.         String string = "H e l l o ! n o w c o d e r";
    6.         Scanner scanner= new Scanner(System.in);
    7.         String word = scanner.next();
    8.         scanner.close();
    9.         System.out.println(check(string, word));
    10.     }
    11.  
    12.     public static int check(String str, String word) {
    13.  
    14.         //write your code here......
    15.         char query = word.charAt(0);
    16.         int count = 0;
    17.         for (int i = 0; i < str.length(); i++) {
    18.             if (str.charAt(i) == query) {
    19.                 count++;
    20.             }
    21.         }
    22.         return count;
    23.  
    24.     }
    25. }

    JAVA31 十进制数转二进制数

    1. import java.util.*;
    2.  
    3. public class Main {
    4.     public static void main(String[] args) {
    5.         Scanner scanner = new Scanner(System.in);
    6.         int num = scanner.nextInt();
    7.  
    8.         //write your code here......
    9.         System.out.println(Integer.toBinaryString(num));
    10.  
    11.     }
    12. }

    JAVA33 掷骰子游戏

    1. import java.util.Random;
    2. import java.util.Scanner;
    3.  
    4. public class Main {
    5.  
    6.     public static void main(String[] args) {
    7.         Scanner scanner = new Scanner(System.in);
    8.         while (scanner.hasNextInt()) {
    9.             int seed = scanner.nextInt();
    10.             Random random = new Random(seed);
    11.  
    12.             //write your code here......
    13.             System.out.println(random.nextInt(6) + 1);
    14.  
    15.         }
    16.     }
    17.  
    18. }

    JAVA34 求绝对值，平方根，对数，正弦值

    1. import java.util.Scanner;
    2.  
    3. public class Main {
    4.     public static void main(String[] args) {
    5.         Scanner scanner=new Scanner(System.in);
    6.         double num = scanner.nextDouble();
    7.  
    8.         //write your code here......
    9.         System.out.println(Math.abs(num));
    10.         System.out.println(Math.sqrt(num));
    11.         System.out.println(Math.log(num));
    12.         System.out.println(Math.sin(num));
    13.  
    14.     }
    15. }

    JAVA35 输出某一年的各个月份的天数

    1. import java.util.Calendar;
    2. import java.util.Scanner;
    3.  
    4. public class Main {
    5.     public static void main(String[] args) {
    6.         Scanner console = new Scanner(System.in);
    7.         int year = console.nextInt();
    8.  
    9.         //write your code here......
    10.         Calendar c = Calendar.getInstance();
    11.         for (int month = 1; month <= 12; month++) {
    12.             c.set(year, month - 1, 1);
    13.             System.out.println(year + "年" + month + "月:" + c.getActualMaximum(Calendar.DAY_OF_MONTH) + "天");
    14.         }
    15.  
    16.     }
    17. }

    JAVA36 日期换算

    1. import java.text.ParseException;
    2. import java.text.SimpleDateFormat;
    3. import java.util.Date;
    4. import java.util.Scanner;
    5.  
    6. public class Main {
    7.     public static void main(String[] args) throws ParseException {
    8.         SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
    9.         Scanner in = new Scanner(System.in);
    10.         String str1 = in.nextLine();
    11.  
    12.         //write your code here......
    13.         try {
    14.             Date date = new SimpleDateFormat("yyyy MM dd HH mm ss").parse(str1);
    15.             System.out.println("北京时间为：" + new SimpleDateFormat("yyyy-MM-dd HH:mm:ss").format(date));
    16.             System.out.println("纽约时间为：" + new SimpleDateFormat("yyyy-MM-dd HH:mm:ss").format(date.getTime() - 12 * 60 * 60 * 1000));
    17.             
    18.         } catch (ParseException ex) {
    19.             System.out.println("您输入的数据不合理");
    20.         }
    21.  
    22.     }
    23. }

    JAVA37 判断学生成绩

    1. import java.util.*;
    2.  
    3. public class Main {
    4.     public static void main(String[] args) {
    5.         Scanner scanner = new Scanner(System.in);
    6.         int score = scanner.nextInt();
    7.  
    8.         //write your code here......
    9.         try {
    10.             if (0 <= score && score <= 100) {
    11.                 System.out.println(score);
    12.             } else {
    13.                 throw new ScoreException("分数不合法");
    14.             }
    15.         } catch (ScoreException ex) {
    16.             System.out.println(ex.getMessage());
    17.         }
    18.     }
    19. }
    20.  
    21. class ScoreException extends Exception {
    22.  
    23.     //write your code here......
    24.     public ScoreException() {
    25.         super();
    26.     }
    27.     
    28.     public ScoreException(String message) {
    29.         super(message);
    30.     }
    31.  
    32. }

    JAVA38 字符串去重

    1. import java.util.HashSet;
    2. import java.util.Scanner;
    3.  
    4. public class Main {
    5.     public static void main(String[] args) {
    6.         Scanner scanner = new Scanner(System.in);
    7.         String str = scanner.nextLine();
    8.         scanner.close();
    9.         HashSet hs = new HashSet<>();
    10.  
    11.         //write your code here......
    12.         for (int i = 0; i < str.length(); i++) {
    13.             hs.add(str.charAt(i));
    14.         }
    15.  
    16.         for (char c:hs) {
    17.             System.out.print(c);
    18.         }
    19.     }
    20. }

    JAVA39 集合遍历

    1. import java.util.ArrayList;
    2. import java.util.Iterator;
    3. import java.util.List;
    4. import java.util.Scanner;
    5.  
    6. public class Main {
    7.     public static void main(String[] args) {
    8.         Scanner scanner = new Scanner(System.in);
    9.         List list = new ArrayList<>();
    10.         int num1 = scanner.nextInt();
    11.         int num2 = scanner.nextInt();
    12.         int num3 = scanner.nextInt();
    13.         int num4 = scanner.nextInt();
    14.         int num5 = scanner.nextInt();
    15.         scanner.close();
    16.         list.add(num1);
    17.         list.add(num2);
    18.         list.add(num3);
    19.         list.add(num4);
    20.         list.add(num5);
    21.         System.out.print("普通for循环:");
    22.  
    23.         //write your code here......
    24.         for (int i = 0; i < list.size(); i++) {
    25.             System.out.print(list.get(i) + " ");
    26.         }
    27.         
    28.  
    29.         System.out.println();
    30.         System.out.print("增强for循环:");
    31.  
    32.         //write your code here......
    33.         for (Integer x : list) {
    34.             System.out.print(x + " ");
    35.         }
    36.         
    37.  
    38.         System.out.println();
    39.         System.out.print("迭代器遍历:");
    40.  
    41.         //write your code here......
    42.         Iterator iter = list.listIterator();
    43.         while (iter.hasNext()) {
    44.             System.out.print(iter.next() + " ");
    45.         }
    46.  
    47.         System.out.println();
    48.     }
    49. }

    JAVA40 排队系统

    1. import java.util.*;
    2.  
    3. public class Main {
    4.     public static void main(String[] args) {
    5.         Guest guest1 = new Guest("小明",false);
    6.         Guest guest2 = new Guest("小军",false);
    7.         Guest vipGuest = new Guest("小红",true);
    8.         Deque deque = new ArrayDeque<>();
    9.         deque.add(guest1);
    10.         deque.add(guest2);
    11.  
    12.         //write your code here......
    13.         deque.push(vipGuest);
    14.         
    15.  
    16.         System.out.println(deque);
    17.     }
    18. }
    19. class Guest{
    20.     String name;
    21.     Boolean vip;
    22.  
    23.     @Override
    24.     public String toString() {
    25.         return name;
    26.     }
    27.  
    28.     public Guest(String name, Boolean vip) {
    29.         this.name = name;
    30.         this.vip = vip;
    31.  
    32.     }
    33. }

    JAVA41 Head and Tail of the Queue

    1. import java.util.ArrayDeque;
    2. import java.util.Scanner;
    3.  
    4. public class Main {
    5.  
    6.     public static void main(String[] args) {
    7.         ArrayDeque deque = new ArrayDeque();
    8.  
    9.         Scanner scanner = new Scanner(System.in);
    10.         while (scanner.hasNext()) {
    11.             String name = scanner.next();
    12.             // 初始化队列中的数据
    13.             deque.offerLast(name);
    14.         }
    15.  
    16.         // write your code here......
    17.         boolean fromFirst = true;
    18.         while (!deque.isEmpty()) {
    19.             if (fromFirst) {
    20.                 System.out.println(deque.pollFirst());
    21.             } else {
    22.                 System.out.println(deque.pollLast());
    23.             }
    24.             fromFirst = !fromFirst;
    25.         }
    26.  
    27.     }
    28.  
    29. }

    JAVA42 统计一句话中重复单词的个数

    1. import java.util.*;
    2.  
    3. public class Main {
    4.     public static void main(String[] args) {
    5.         Scanner scanner = new Scanner(System.in);
    6.         String line = scanner.nextLine();
    7.         Map map = new LinkedHashMap();
    8.  
    9.         //write your code here......
    10.         for (int i = 0; i < line.length(); i++) {
    11.             char ch = line.charAt(i);
    12.             if (('A' <= ch && ch <= 'Z') || ('a' <= ch && ch <= 'z')) {
    13.                 map.put(ch, map.getOrDefault(ch, 0) + 1);
    14.             }
    15.         }
    16.         
    17.  
    18.         Set> entrys = map.entrySet();
    19.         for (Map.Entry entry : entrys) {
    20.             System.out.println(entry.getKey() + ":" + entry.getValue());
    21.         }
    22.     }
    23. }

    JAVA43 map简单应用

    1. import java.util.*;
    2.  
    3. public class Main {
    4.     public static void main(String[] args) {
    5.         Scanner scanner  = new Scanner(System.in);
    6.         String name = scanner.next();
    7.         Map map = new HashMap();
    8.         map.put(1, "Amy");
    9.         map.put(2, "Joe");
    10.         map.put(3, "Tom");
    11.         map.put(4, "Susan");
    12.  
    13.         //write your code here......
    14.         for (Integer key : map.keySet()) {
    15.             System.out.println(key + ":" + map.get(key));
    16.         }
    17.         map.put(5, name);
    18.         map.remove(4);
    19.         map.replace(3, "Tommy");
    20.         System.out.println();
    21.         for (Integer key : map.keySet()) {
    22.             System.out.println(key + ":" + map.get(key));
    23.         }
    24.  
    25.     }
    26. }

    JAVA44 集合排序

    1. import java.util.ArrayList;
    2. import java.util.Collections;
    3. import java.util.List;
    4. import java.util.Scanner;
    5.  
    6. public class Main {
    7.     public static void main(String[] args) {
    8.         Scanner scanner = new Scanner(System.in);
    9.         Customer customer1 = new Customer("小明",scanner.nextInt());
    10.         Customer customer2 = new Customer("小军",scanner.nextInt());
    11.         Customer customer3 = new Customer("小红",scanner.nextInt());
    12.         List customers = new ArrayList<>();
    13.         customers.add(customer1);
    14.         customers.add(customer2);
    15.         customers.add(customer3);
    16.  
    17.         //write your code here......
    18.         Collections.sort(customers);
    19.  
    20.         System.out.println(customers);
    21.  
    22.     }
    23. }
    24.  
    25. class Customer implements Comparable{
    26.     private String name;
    27.     private int consumption;
    28.  
    29.     public Customer(String name, int consumption) {
    30.         this.name = name;
    31.         this.consumption = consumption;
    32.     }
    33.  
    34.     @Override
    35.     public String toString() {
    36.         return "Customer{" +
    37.                 "name='" + name + '\'' +
    38.                 ", consumption=" + consumption +
    39.                 '}';
    40.     }
    41.  
    42.     //write your code here......
    43.     public int getConsumption() {
    44.         return consumption;
    45.     }
    46.     
    47.     public int compareTo(Customer customer) {
    48.         return customer.getConsumption() - this.consumption;
    49.     }
    50.  
    51. }

    JAVA45 判断各类型字符个数

    1. import java.util.Scanner;
    2.  
    3. public class Main {
    4.     public static void main(String[] args) {
    5.         int numbers = 0;
    6.         int words = 0;
    7.         int space = 0;
    8.         int other = 0;
    9.         Scanner scanner = new Scanner(System.in);
    10.         String str = scanner.nextLine();
    11.  
    12.         //write your code here......
    13.         for (int i = 0; i < str.length(); i++) {
    14.             char ch = str.charAt(i);
    15.             if (('a' <= ch && ch <= 'z') || ('A' <= ch && ch <= 'Z')) {
    16.                 words++;
    17.             } else if ('0' <= ch && ch <= '9') {
    18.                 numbers++;
    19.             } else if (ch == ' ') {
    20.                 space++;
    21.             } else {
    22.                 other++;
    23.             }
    24.         }
    25.  
    26.         System.out.println("英文字母"+words+"数字"+numbers+"空格"+space+"其他"+other);
    27.     }
    28. }

    JAVA46 编写个人所得税计算程序

    1. import java.util.*;
    2.  
    3. public class Main {
    4.     public static void main(String[] args) {
    5.         List employees = new ArrayList<>();
    6.  
    7.         //write your code here......
    8.         employees.add(new Employee("小明", 2500));
    9.         employees.add(new Employee("小军", 8000));
    10.         employees.add(new Employee("小红", 100000));
    11.         
    12.         for (Employee employee : employees) {
    13.             double salaryForTax = employee.getSalary() - 3500;
    14.             double tax = 0;
    15.             if (salaryForTax <= 0) {
    16.                 tax = 0;
    17.             } else if (salaryForTax <= 1500) {
    18.                 tax = salaryForTax * 0.03;
    19.             } else if (salaryForTax <= 4500) {
    20.                 tax = salaryForTax * 0.10 - 105;
    21.             } else if (salaryForTax <= 9000) {
    22.                 tax = salaryForTax * 0.20 - 555;
    23.             } else if (salaryForTax <= 35000) {
    24.                 tax = salaryForTax * 0.25 - 1005;
    25.             } else if (salaryForTax <= 55000) {
    26.                 tax = salaryForTax * 0.30 - 2755;
    27.             } else if (salaryForTax <= 80000) {
    28.                 tax = salaryForTax * 0.35 - 5505;
    29.             } else {
    30.                 tax = salaryForTax * 0.45 - 13505;
    31.             }
    32.             System.out.println(employee.getName() + "应该缴纳的个人所得税是：" + String.format("%.1f", tax));
    33.         }
    34.  
    35.     }
    36. }
    37. class Employee{
    38.     private String name;
    39.     private double salary;
    40.     public Employee(String name, double salary) {
    41.         this.name = name;
    42.         this.salary = salary;
    43.     }
    44.     public String getName() {
    45.         return name;
    46.     }
    47.  
    48.     public double getSalary() {
    49.         return salary;
    50.     }
    51. }

    JAVA47 记录点赞用户

    1. import java.util.*;
    2.  
    3. public class Main {
    4.  
    5.     public static void main(String[] args) {
    6.         LikeRecorder recorder = new LikeRecorderImpl();
    7.  
    8.         Scanner scanner = new Scanner(System.in);
    9.         while (scanner.hasNext()) {
    10.             String name = scanner.next();
    11.             recorder.like(name);
    12.         }
    13.  
    14.         System.out.println(Arrays.toString(recorder.getLikeUsers()));
    15.     }
    16.  
    17. }
    18.  
    19. /**
    20.  * 点赞记录器
    21.  */
    22. interface LikeRecorder {
    23.  
    24.     /**
    25.      * 若用户没有点赞过，则记录此次点赞行为。
    26.      * 若用户曾经点赞过，则删除用户点赞记录。
    27.      *
    28.      * @param username 用户名
    29.      */
    30.     void like(String username);
    31.  
    32.     /**
    33.      * 返回所有点赞的用户名
    34.      *
    35.      * @return 用户名数组
    36.      */
    37.     String[] getLikeUsers();
    38.  
    39. }
    40.  
    41. class LikeRecorderImpl implements LikeRecorder {
    42.  
    43.     // write your code here......
    44.     private HashSet users = new HashSet<>();
    45.     
    46.     public void like(String username) {
    47.         if (users.contains(username)) {
    48.             users.remove(username);
    49.         } else {
    50.             users.add(username);
    51.         }
    52.     }
    53.     
    54.     public String[] getLikeUsers() {
    55.         return users.toArray(new String[users.size()]);
    56.     }
    57.  
    58. }

    JAVA48 回文数判断

    1. import java.util.Scanner;
    2.  
    3. public class Main {
    4.     public static void main(String[] args) {
    5.         Scanner console = new Scanner(System.in);
    6.         Main main = new Main();
    7.         int number = console.nextInt();
    8.         System.out.println(main.palindromeNumber(number));
    9.     }
    10.  
    11.     public Boolean palindromeNumber(int number) {
    12.  
    13.         //write your code here......
    14.         StringBuffer numStr = new StringBuffer("" + number);
    15.         return numStr.toString().equals(numStr.reverse().toString());
    16.  
    17.     }
    18. }

    JAVA49 判断素数个数

    1. import java.util.Scanner;
    2.  
    3. public class Main {
    4.     public static void main(String[] args) {
    5.         Scanner scanner = new Scanner(System.in);
    6.         int start = scanner.nextInt();
    7.         int end = scanner.nextInt();
    8.         method(start,end);
    9.     }
    10.  
    11.     public static void method(int start, int end) {
    12.         int count=0;
    13.  
    14.         //write your code here......
    15.         if (start > end) {
    16.             int temp = start;
    17.             start = end;
    18.             end = temp;
    19.         }
    20.         
    21.         for (int i = start <= 2 ? 3 : start; i <= end; ++i) {
    22.             boolean isPrime = true;
    23.             for (int j = 2; j * j <= i; j++) {
    24.                 if (i % j == 0) {
    25.                     isPrime = false;
    26.                     break;
    27.                 }
    28.             }
    29.             count += isPrime ? 1 : 0;
    30.         }
    31.         
    32.  
    33.         System.out.println(start+"到"+end+"之间有"+count+"个大于2的素数");
    34.     }
    35. }

    JAVA50 根据周长求面积

    1. import java.util.Scanner;
    2.  
    3. public class Main {
    4.  
    5.     public static void main(String[] args) {
    6.         Scanner scanner = new Scanner(System.in);
    7.         while (scanner.hasNextDouble()) {
    8.             double s = scanner.nextDouble();
    9.             // Circle和Square是需要你定义的类
    10.             System.out.println(String.format("%.3f",new Circle(s).getArea()));
    11.             System.out.println(String.format("%.3f", new Square(s).getArea()));
    12.         }
    13.     }
    14.  
    15. }
    16.  
    17. class Shape {
    18.  
    19.     private double s; // 周长
    20.  
    21.     public Shape(double s) {
    22.         this.s = s;
    23.     }
    24.  
    25.     public double getS() {
    26.         return s;
    27.     }
    28.  
    29. }
    30.  
    31. interface Area {
    32.     double getArea(); // 面积
    33. }
    34.  
    35. // 圆形
    36. class Circle extends Shape implements Area {
    37.  
    38.     //write your code here......
    39.     public Circle(double s) {
    40.         super(s);
    41.     }
    42.     
    43.     public double getArea() {
    44.         return getS() * getS() / (4 * Math.PI);
    45.     }
    46.  
    47. }
    48.  
    49. // 方形
    50. class Square extends Shape implements Area {
    51.  
    52.     //write your code here......
    53.     public Square(double s) {
    54.         super(s);
    55.     }
    56.     
    57.     public double getArea() {
    58.         return getS() * getS() / 16;
    59.     }
    60.  
    61. }

    JAVA51 冒泡排序

    1. import java.util.Arrays;
    2. import java.util.Scanner;
    3. public class Main {
    4.     public static void main(String[] args) {
    5.         Scanner scanner = new Scanner(System.in);
    6.          int[] arr = new int[7];
    7.         for (int i = 0; i < arr.length; i++) {
    8.             arr[i] = scanner.nextInt();
    9.         }
    10.         scanner.close();
    11.  
    12.         //write your code here......
    13.         for (int j = arr.length - 1; j > 0; j--) {
    14.             for (int i = j - 1; i >= 0; i--) {
    15.                 if (arr[i] > arr[j]) {
    16.                     int temp = arr[i];
    17.                     arr[i] = arr[j];
    18.                     arr[j] = temp;
    19.                 }
    20.             }
    21.         }
    22.         
    23.  
    24.         for (int k = 0; k < arr.length; k++) {
    25.             System.out.print(arr[k]+" ");
    26.         }
    27.     }
    28. }
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  • 原文地址：https://blog.csdn.net/liulizhi1996/article/details/127970735