Spinner

• spinneradapter

package com.example.spinner

import android.app.Activity
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import android.widget.BaseAdapter
import android.widget.TextView

class SpinnerAdapter(activity: Activity, val resouceId: Int, var datas: List<String>) :
    BaseAdapter() {

    class viewholder(val number: TextView)

    override fun getCount(): Int {
        return datas.size
    }

    override fun getItem(p0: Int): Any {
        return datas[p0]
    }

    override fun getItemId(p0: Int): Long {
        return p0.toLong()
    }

    override fun getView(
        position: Int,
        convertView: View?,
        parent: ViewGroup
    ): View {
        val view: View
        val holder: viewholder
        if (convertView == null) {
            view = LayoutInflater.from(parent.context).inflate(resouceId, parent, false)
            val number = view.findViewById<TextView>(R.id.number)
            holder = viewholder(number)
            view.tag = holder
        } else {
            view = convertView
            holder = view.tag as viewholder
        }
        val item = getItem(position)
        if (item != null) {
            holder.number.text = item.toString()
        }

        return view
    }
}
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• MainActivity代码

package com.example.spinner

import android.content.Context
import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.util.AttributeSet
import android.view.View
import android.widget.*
import android.widget.SpinnerAdapter

class MainActivity : AppCompatActivity() {

    private var datas = ArrayList<String>()

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        for(i in 0..20){
            datas.add(i.toString())
        }
        val spinner = findViewById<Spinner>(R.id.spinner)
        val adapter = SpinnerAdapter(this,R.layout.number_item,datas)
        spinner.adapter = adapter

//        spinner.setOnItemClickListener { adapterView, view, i, l ->
//            val number = datas[i]
//            Toast.makeText(this,number,Toast.LENGTH_SHORT).show()
//        }
        spinner.onItemSelectedListener = object : AdapterView.OnItemSelectedListener{
            override fun onItemSelected(p0: AdapterView<*>?, p1: View?, p2: Int, p3: Long) {
                val number = datas[p2]
                println(number)
            }

            override fun onNothingSelected(p0: AdapterView<*>?) {
                TODO("Not yet implemented")
            }
        }
    }
}
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• Spinner.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <Spinner
        android:layout_width="match_parent"
        android:layout_height="100dp"
        android:id="@+id/spinner"
        android:spinnerMode="dialog"
        android:prompt="@string/app_name"/>

</LinearLayout>
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item.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:id="@+id/spinner">

    <TextView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/number"/>

</LinearLayout>
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