Java 为什么不是';是否异步停止重新创建listview?
我真的不知道怎么问这个但是 我的代码旨在通过单击按钮生成ListView输入 当我单击按钮时,它应该.execute()一个异步函数,它获取一个项目列表,并使用自定义适配器将它们添加到ArrayListJava 为什么不是';是否异步停止重新创建listview?,java,android,listview,android-asynctask,Java,Android,Listview,Android Asynctask,我真的不知道怎么问这个但是 我的代码旨在通过单击按钮生成ListView输入 当我单击按钮时,它应该.execute()一个异步函数,它获取一个项目列表,并使用自定义适配器将它们添加到ArrayList 问题是,当我按下按钮时,它会生成列表并将其添加到ListView,而不是。。。1,2,3,4,5,…20它是按随机顺序排列的。1,2,5,1,3,0,6,7,8,3,1 如果我向上或向下滚动ListView,它会改变 activity_main.xml: <?xml version="1.
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/activity_main"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
tools:context=".MainActivity">
<Button
android:id="@+id/bLoadData"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:text="Load api data" />
<ListView
android:id="@+id/lvMovies"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:layout_above="@id/bLoadData"
android:background="#efefef" />
</RelativeLayout>
结果_layout.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="wrap_content"
android:orientation="vertical">
<LinearLayout
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:orientation="horizontal">
<ImageView android:id="@+id/ivPosters"
android:layout_width="120dp"
android:layout_height="120dp"
android:src="@drawable/place_holder_img"/>
<TextView
android:id="@+id/results_layout_tv_movie_name"
android:layout_width="0dp"
android:layout_height="fill_parent"
android:layout_weight="1"
android:paddingBottom="10dp"
android:paddingLeft="20dp"
android:paddingStart="20dp"
android:paddingTop="10dp"
android:text="hellow"
android:textColor="#000"
android:textSize="20sp" />
</LinearLayout>
</LinearLayout>
MainActivity.class:
package com.example.zdroa.testinggrounds;
import android.os.AsyncTask;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.AdapterView;
import android.widget.Button;
import android.widget.ListView;
import java.util.ArrayList;
import java.util.HashMap;
public class MainActivity extends AppCompatActivity {
static ArrayList<HashMap<String, String>> posters;
ListView listView;
Button button;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
listView = (ListView) findViewById(R.id.lvMovies);
listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
System.out.println(posters.get(position).values().toString());
}
});
button = (Button) findViewById(R.id.bLoadData);
button.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
posters = new ArrayList<>();
ImageLoadTask ilt = new ImageLoadTask();
ilt.execute();
}
});
}
private class ImageLoadTask extends AsyncTask<Void, Void, ArrayList<HashMap<String, String>>> {
@Override
protected ArrayList<HashMap<String, String>> doInBackground(Void... params) {
posters = getPathFromAPI();
return posters;
}
@Override
protected void onPostExecute(ArrayList<HashMap<String, String>> result) {
SearchAdapter adapter = new SearchAdapter(MainActivity.this, result);
listView.setAdapter(adapter);
}
private ArrayList<HashMap<String, String>> getPathFromAPI() {
String moviePaths[] = new String[10];
for (int i = 0; i < moviePaths.length; i++) {
HashMap<String, String> map = new HashMap<>();
String s = "path";
map.put(s, s + "_" + i);
moviePaths[i] = "path_" + i;
posters.add(map);
}
return posters;
}
}
}
package com.example.zdroa.testinggrounds;
导入android.os.AsyncTask;
导入android.os.Bundle;
导入android.support.v7.app.AppActivity;
导入android.view.view;
导入android.widget.AdapterView;
导入android.widget.Button;
导入android.widget.ListView;
导入java.util.ArrayList;
导入java.util.HashMap;
公共类MainActivity扩展了AppCompatActivity{
静态ArrayList海报;
列表视图列表视图;
按钮;
@凌驾
创建时受保护的void(Bundle savedInstanceState){
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
listView=(listView)findViewById(R.id.lvMovies);
setOnItemClickListener(新的AdapterView.OnItemClickListener(){
public void onItemClick(AdapterView父对象、视图、整型位置、长id){
System.out.println(posters.get(position.values().toString());
}
});
按钮=(按钮)findViewById(R.id.bLoadData);
setOnClickListener(新视图.OnClickListener(){
@凌驾
公共void onClick(视图v){
海报=新的ArrayList();
ImageLoadTask ilt=新建ImageLoadTask();
ilt.execute();
}
});
}
私有类ImageLoadTask扩展了AsyncTask{
@凌驾
受保护的ArrayList doInBackground(无效…参数){
海报=getPathFromAPI();
返回海报;
}
@凌驾
受保护的void onPostExecute(ArrayList结果){
SearchAdapter=新的SearchAdapter(MainActivity.this,result);
setAdapter(适配器);
}
私有ArrayList getPathFromAPI(){
字符串moviepath[]=新字符串[10];
对于(int i=0;i
SearchAdapter.class:
package com.example.zdroa.testinggrounds;
import android.content.Context;
import android.graphics.drawable.Drawable;
import android.support.v4.content.ContextCompat;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.ImageView;
import android.widget.TextView;
import com.squareup.picasso.Picasso;
import java.util.ArrayList;
import java.util.HashMap;
public class SearchAdapter extends BaseAdapter {
private Context mContext;
private ArrayList<HashMap<String, String>> array;
private ImageView imageView;
private TextView textView;
SearchAdapter(Context context, ArrayList<HashMap<String, String>> paths) {
mContext = context;
array = paths;
}
@Override
public int getCount() {
return array.size();
}
@Override
public Object getItem(int position) {
return null;
}
@Override
public long getItemId(int position) {
return 0;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
if (convertView == null) {
convertView = View.inflate(mContext, R.layout.results_layout, null);
imageView = (ImageView) convertView.findViewById(R.id.ivPosters);
textView = (TextView) convertView.findViewById(R.id.results_layout_tv_movie_name);
}
Drawable drawable = ContextCompat.getDrawable(mContext, R.drawable.place_holder_img);
String link_end = array.get(position).values().toString();
Picasso.with(mContext)
.load("http://image.tmdb.org/t/p/w185" + link_end)
// .resize(width, (int) (width * 1.5))
.placeholder(drawable)
.into(imageView);
textView.setText(position+"");
return convertView;
}
}
package com.example.zdroa.testinggrounds;
导入android.content.Context;
导入android.graphics.drawable.drawable;
导入android.support.v4.content.ContextCompat;
导入android.view.view;
导入android.view.ViewGroup;
导入android.widget.BaseAdapter;
导入android.widget.ImageView;
导入android.widget.TextView;
导入com.squareup.picasso.picasso;
导入java.util.ArrayList;
导入java.util.HashMap;
公共类SearchAdapter扩展了BaseAdapter{
私有上下文;
私有数组列表数组;
私人影像视图;
私有文本视图文本视图;
SearchAdapter(上下文、ArrayList路径){
mContext=上下文;
数组=路径;
}
@凌驾
public int getCount(){
返回array.size();
}
@凌驾
公共对象getItem(int位置){
返回null;
}
@凌驾
公共长getItemId(int位置){
返回0;
}
@凌驾
公共视图getView(int位置、视图转换视图、视图组父视图){
if(convertView==null){
convertView=查看.充气(mContext,R.layout.results\u layout,null);
imageView=(imageView)convertView.findViewById(R.id.ivd);
textView=(textView)convertView.findViewById(R.id.results\u layout\u tv\u movie\u name);
}
Drawable Drawable=ContextCompat.getDrawable(mContext,R.Drawable.place\u holder\u img);
字符串link_end=array.get(position).values().toString();
毕加索(McContext)
.加载(“http://image.tmdb.org/t/p/w185“+链接(结束)
//.调整大小(宽度(整数)(宽度*1.5))
.占位符(可绘制)
.进入(图像视图);
textView.setText(位置+“”);
返回视图;
}
}
在Asyntask类的onPost中
在为listview创建和设置适配器之后
在列表视图中列出您正在使用的列表
list=new ArrayList<>();
list=newarraylist();
只有当convertview为空时,才会设置imageview和textview引用…将这些行从括号中移出。如果我将imageview内的图像大小从120乘以120dp更改为50乘以50dp(10结果),则不会发生问题,但是如果我也将结果从10改为20,那么代码中会再次出现这样的情况,即您应该只生成10项,而不是20项。每次它都会按顺序生成它们。问题出在其他地方只有当convertview为空时,才会设置imageview和textview引用…请将这些行移出括号。@ElDuderino将问题答复为答案,以便我可以正确标记它