为什么不同步停止重新创建列表视图？

Question

我真的不确定如何问这个但是......

我的代码用于在按钮点击时生成ListView输入。

当我点击按钮时，它应该.execute（）一个Async，它接受一个项目列表并将它们添加到一个ArrayList＆lt; HashMap＆lt;字符串，字符串＆gt; ＆GT;使用自定义适配器。

问题是，当我按下按钮时，它会生成列表并将其添加到ListView中，而不是去... 1,2,3,4,5 ...... 20它进入随机顺序。 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中：

<?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>

results_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;
        }
    }
}

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;
    }
}

Answer 1

在Asyntask类中的onPost

在为listview创建和设置适配器之后

制作您在列表视图中使用的列表

list=new ArrayList<>();

Answer 2

您的imageview和textview引用仅在convertview为null时设置...将这些行移出括号。