Android Studio Kotlin开发之ListView

Android Studio Kotlin开发之ListView

ListView的简单用法

效果图

知识讲解

ArrayAdapter

在下文源代码中有这样一句

val adapter = ArrayAdapter<String>(this,android.R.layout.simple_list_item_1,data)

这段代码是创建一个数组适配器的代码，里面有三个参数，第一个参数是上下文，就是当前的Activity, 第二个参数是android sdk中自己内置的一个布局，它里面只有一个TextView，这个参数是表明我们数组中每一条数据的布局是这个view，就是将每一条数据都显示在这个view上面；第三个参数就是我们要显示的数据。listView会根据这三个参数，遍历adapterData里面的每一条数据，读出一条，显示到第二个参数对应的布局中，这样就形成了我们看到的listView. ¹

源代码

MainActivity.kt

package com.example.listviewtest

import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.widget.ArrayAdapter
import android.widget.ListAdapter
import kotlinx.android.synthetic.main.activity_main.*

class MainActivity : AppCompatActivity() {
     
    private val data = listOf("apple","pear","apricot","peach","grape","banana","pineapple","plum","watermelon","orange","lemon","mango","strawberry",
        "medlar","mulberry","nectarine","cherry","pomegranate","fig","persimmon")
    override fun onCreate(savedInstanceState: Bundle?) {
     
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
        val adapter = ArrayAdapter<String>(this,android.R.layout.simple_list_item_1,data)
        listView.adapter  = adapter
    }
}

activity_main.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <ListView
        android:id="@+id/listView"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />

LinearLayout>

定制ListView界面

效果图

源代码

MainActivity.kt

package com.example.listviewtest

import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.widget.ArrayAdapter
import android.widget.ListAdapter
import kotlinx.android.synthetic.main.activity_main.*
import java.util.ArrayList

class MainActivity : AppCompatActivity() {
     
//    private val data = listOf("apple","pear","apricot","peach","grape","banana","pineapple","plum","watermelon","orange","lemon","mango","strawberry",
//        "medlar","mulberry","nectarine","cherry","pomegranate","fig","persimmon")

    private val fruitList = ArrayList<Fruit>()

    override fun onCreate(savedInstanceState: Bundle?) {
     
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
        initFruits()
        val adapter = FruitAdapter(this,R.layout.fruit_item,fruitList)
        listView.adapter  = adapter
    }

    private fun initFruits() {
     
        repeat(2){
     
            fruitList.add(Fruit("apple",R.drawable.pricture))
            fruitList.add(Fruit("banana",R.drawable.pricture))
            fruitList.add(Fruit("orange",R.drawable.pricture))
            fruitList.add(Fruit("watermelon",R.drawable.pricture))
            fruitList.add(Fruit("pear",R.drawable.pricture))
            fruitList.add(Fruit("grape",R.drawable.pricture))
            fruitList.add(Fruit("pineapple",R.drawable.pricture))
            fruitList.add(Fruit("strawberry",R.drawable.pricture))
            fruitList.add(Fruit("cherry",R.drawable.pricture))
            fruitList.add(Fruit("mango",R.drawable.pricture))
        }
    }
}

fruitAdapter.kt

package com.example.listviewtest

import android.app.Activity
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import android.widget.ArrayAdapter
import android.widget.ImageView
import android.widget.TextView

class FruitAdapter(activity: Activity, val resourceId: Int, data: List<Fruit>) : ArrayAdapter<Fruit>(activity, resourceId, data) {
     

    override fun getView(position: Int, convertView: View?, parent: ViewGroup): View {
     
        val view = LayoutInflater.from(context).inflate(resourceId, parent, false)
        val fruitImage: ImageView = view.findViewById(R.id.fruitImage)
        val fruitName: TextView = view.findViewById(R.id.fruitName)
        val fruit = getItem(position)
        if (fruit!=null){
     
            fruitImage.setImageResource(fruit.imageId)
            fruitName.text = fruit.name
        }
        return view
    }
}

Fruit.kt

package com.example.listviewtest

class Fruit(val name:String,val imageId:Int)

activity_main.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <ListView
        android:id="@+id/listView"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />

LinearLayout>

fruit_item.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="60dp">

    <ImageView
        android:id="@+id/fruitImage"
        android:layout_width="40dp"
        android:layout_height="40dp"
        android:layout_gravity="center_vertical"
        android:layout_marginLeft="10dp"/>

    <TextView
        android:id="@+id/fruitName"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center_vertical"
        android:layout_marginLeft="10dp" />

LinearLayout>

Referecces

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1. ArrayAdapter参数的理解 ↩︎