【发布时间】：2020-04-26 18:57:40
【问题描述】：
我在使用 listView 时遇到问题，因为我在 listview 中显示了很多图像（关于内存）
我需要将 listview 转换为 recyclerview
问题：
当我在手机上显示图像时，使用最后一个视图，你做了很多内存阻塞， 它导致应用程序停止，所以我想将 List View 转换为 RecycleView。
主活动：
package com.masreta87.hussain
import android.app.Activity
import android.content.pm.PackageManager
import android.graphics.Bitmap
import android.graphics.drawable.BitmapDrawable
import android.os.Build
import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.os.Environment
import android.view.View
import android.widget.AdapterView
import android.widget.ImageView
import android.widget.ListView
import android.widget.Toast
import androidx.core.app.ActivityCompat
import androidx.core.content.ContextCompat
import androidx.core.view.get
import java.io.File
import java.io.FileOutputStream
import java.io.OutputStream
import java.lang.Exception
import java.util.jar.Manifest
import androidx.core.content.ContextCompat.getSystemService
import android.icu.lang.UCharacter.GraphemeClusterBreak.T
import androidx.core.app.ComponentActivity.ExtraData
import androidx.core.content.ContextCompat.getSystemService
import android.icu.lang.UCharacter.GraphemeClusterBreak.T
import android.util.Log
import kotlinx.android.synthetic.*
class MainActivity : AppCompatActivity() {
lateinit var Img:ListView
lateinit var ImgArr:ArrayList<DataImg>
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
Img=findViewById(R.id.listviewB)
ImgArr=ArrayList()
ImgArr.add(DataImg(R.drawable.h))
ImgArr.add(DataImg(R.drawable.hh))
ImgArr.add(DataImg(R.drawable.hhh))
ImgArr.add(DataImg(R.drawable.v2))
ImgArr.add(DataImg(R.drawable.v3))
ImgArr.add(DataImg(R.drawable.v4))
ImgArr.add(DataImg(R.drawable.v5))
ImgArr.add(DataImg(R.drawable.v6))
//ImgArr.add(DataImg(R.drawable.v7))
ImgArr.add(DataImg(R.drawable.v8))
ImgArr.add(DataImg(R.drawable.v9))
Img.adapter=customAdapter(applicationContext,ImgArr)
Img.setOnItemClickListener{parent:AdapterView<*>, view:View, position:Int, id:Long ->
var ImgNa=ImgArr.get(position).image.toString()
Log.d("this",ImgNa)
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M){
if (ContextCompat.checkSelfPermission(this,android.Manifest.permission.WRITE_EXTERNAL_STORAGE )
!=PackageManager.PERMISSION_GRANTED){
ActivityCompat.requestPermissions(this, arrayOf(android.Manifest.permission.WRITE_EXTERNAL_STORAGE)
,100)
}else{
saveImageToStorage(ImgNa)
}
}else{
saveImageToStorage(ImgNa)
}
}
}
override fun onRequestPermissionsResult(
requestCode: Int,
permissions: Array<out String>,
grantResults: IntArray
) {
if (requestCode==100){
if (grantResults.isNotEmpty() && grantResults[0]==PackageManager.PERMISSION_GRANTED){
// saveImageToStorage(ImgNa)
}else{
Toast.makeText(this,"No Permission for save",Toast.LENGTH_SHORT).show()
}
}
}
public fun saveImageToStorage(ImgNa:String){
val externalStorageState=Environment.getExternalStorageState()
if (externalStorageState.equals(Environment.MEDIA_MOUNTED)){
val storeDirectory=Environment.getExternalStorageDirectory().toString()
val rnds = (1000..100000000000).random().toString()
val file=File(storeDirectory,"$rnds.png")//Namephoto
try {
Log.d("output",ImgNa)
val stream:OutputStream =FileOutputStream(file)
var drawable=ContextCompat.getDrawable(applicationContext,ImgNa.toInt()) //edit
var bitmap=(drawable as BitmapDrawable).bitmap
bitmap.compress(Bitmap.CompressFormat.PNG,100,stream)
stream.flush()
stream.close()
Toast.makeText(this,"Image Saved",Toast.LENGTH_LONG).show()
}catch (e:Exception){
e.printStackTrace()
}
}else{
Toast.makeText(this,"unable to access the storage",Toast.LENGTH_SHORT).show()
}
}
}
还有customAdapter
package com.masreta87.hussain
import android.content.Context
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import android.widget.BaseAdapter
import android.widget.ImageView
class customAdapter(var context: Context,var data:ArrayList<DataImg>) :BaseAdapter(){
private class ViewHolder(row:View?){
var ivImage:ImageView
init {
this.ivImage=row?.findViewById(R.id.imageViewN) as ImageView
}
}
override fun getView(position: Int, convertView: View?, parent: ViewGroup?): View {
var view:View?
var viewHolder:ViewHolder
if(convertView==null){
var layout=LayoutInflater.from(context)
view=layout.inflate(R.layout.listview_item,parent,false)
viewHolder=ViewHolder(view)
view.tag=viewHolder
}else{
view=convertView
viewHolder=view.tag as ViewHolder
}
var data:DataImg=getItem(position) as DataImg
viewHolder.ivImage.setImageResource(data.image)
return view as View
}
override fun getItem(position: Int): Any {
return data.get(position)
}
override fun getItemId(position: Int): Long {
return position.toLong()
}
override fun getCount(): Int {
return data.count()
}
}
和DataImg：
package com.masreta87.hussain
class DataImg(var image:Int) {
}
activity_Main.xml：
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout 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/listviewB"
android:layout_width="match_parent"
android:layout_height="match_parent"
/>
</RelativeLayout>
listview_item.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical" android:layout_width="match_parent"
android:layout_height="match_parent">
<ImageView
android:id="@+id/imageViewN"
android:background="@drawable/image_border"
android:layout_width="match_parent"
android:scaleType="fitXY"
android:layout_height="200dp"
/>
</LinearLayout>
【问题讨论】：
-
您只需要创建recyclerview 适配器而不是listview 适配器，并使用与本示例相同的视图并在活动中进行设置
-
替代方法....我建议您使用滑翔图像库，它将您的可绘制对象缓存在内存中。你不会得到任何内存错误
标签： android listview kotlin android-recyclerview