无法暂停活动，java.lang.IndexOutOfBoundsException：无效索引0，大小为0

Question

我保存ListView信息使用onSaveInstanceState()，onRestoreInstanceState() incase用户更改方向。 但是当用户移动到其他活动时，我想要移除ListView信息，因此我使用clear();方法，但出于某种原因，我使用clear();方法得到错误。

的logcat：

07-25 10:00:59.326: E/AndroidRuntime(940): FATAL EXCEPTION: main 
07-25 10:00:59.326: E/AndroidRuntime(940): java.lang.RuntimeException: Unable to pause activity {com.example.project/com.example.project.InternetActivity}: java.lang.IndexOutOfBoundsException: Invalid index 0, size is 0 
07-25 10:00:59.326: E/AndroidRuntime(940): at android.app.ActivityThread.performPauseActivity(ActivityThread.java:3348) 
07-25 10:00:59.326: E/AndroidRuntime(940): at android.app.ActivityThread.performPauseActivity(ActivityThread.java:3305) 
07-25 10:00:59.326: E/AndroidRuntime(940): at android.app.ActivityThread.handlePauseActivity(ActivityThread.java:3288) 
07-25 10:00:59.326: E/AndroidRuntime(940): at android.app.ActivityThread.access$2500(ActivityThread.java:125) 
07-25 10:00:59.326: E/AndroidRuntime(940): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2040) 
07-25 10:00:59.326: E/AndroidRuntime(940): at android.os.Handler.dispatchMessage(Handler.java:99) 
07-25 10:00:59.326: E/AndroidRuntime(940): at android.os.Looper.loop(Looper.java:123) 
07-25 10:00:59.326: E/AndroidRuntime(940): at android.app.ActivityThread.main(ActivityThread.java:4627) 
07-25 10:00:59.326: E/AndroidRuntime(940): at java.lang.reflect.Method.invokeNative(Native Method) 
07-25 10:00:59.326: E/AndroidRuntime(940): at java.lang.reflect.Method.invoke(Method.java:521) 
07-25 10:00:59.326: E/AndroidRuntime(940): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868) 
07-25 10:00:59.326: E/AndroidRuntime(940): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626) 
07-25 10:00:59.326: E/AndroidRuntime(940): at dalvik.system.NativeStart.main(Native Method) 
07-25 10:00:59.326: E/AndroidRuntime(940): Caused by: java.lang.IndexOutOfBoundsException: Invalid index 0, size is 0 
07-25 10:00:59.326: E/AndroidRuntime(940): at java.util.ArrayList.throwIndexOutOfBoundsException(ArrayList.java:257) 
07-25 10:00:59.326: E/AndroidRuntime(940): at java.util.ArrayList.get(ArrayList.java:311) 
07-25 10:00:59.326: E/AndroidRuntime(940): at com.example.project.InternetActivity.onSaveInstanceState(InternetActivity.java:68) 
07-25 10:00:59.326: E/AndroidRuntime(940): at android.app.Activity.performSaveInstanceState(Activity.java:1036) 
07-25 10:00:59.326: E/AndroidRuntime(940): at android.app.Instrumentation.callActivityOnSaveInstanceState(Instrumentation.java:1180) 
07-25 10:00:59.326: E/AndroidRuntime(940): at android.app.ActivityThread.performPauseActivity(ActivityThread.java:3330) 
07-25 10:00:59.326: E/AndroidRuntime(940): ... 12 more 

InternetActivity.java - 我没有加入所有的.java文件，因为它是非常长的。 Instand我刚刚添加了这个问题。

package com.example.project; 

import java.io.BufferedReader; 
import java.io.IOException; 
import java.io.InputStreamReader; 
import java.net.HttpURLConnection; 
import java.net.MalformedURLException; 
import java.net.URL; 
import java.util.ArrayList; 
import java.util.List; 

import org.json.JSONArray; 
import org.json.JSONException; 
import org.json.JSONObject; 

import android.app.ListActivity; 
import android.app.ProgressDialog; 
import android.content.Intent; 
import android.os.AsyncTask; 
import android.os.Bundle; 
import android.view.View; 
import android.view.View.OnClickListener; 
import android.widget.AdapterView; 
import android.widget.AdapterView.OnItemClickListener; 
import android.widget.ArrayAdapter; 
import android.widget.Button; 
import android.widget.EditText; 
import android.widget.ListView; 

public class InternetActivity extends ListActivity implements OnClickListener 
{ 

    final static String TAG = "InternetActivity"; 


    static List<Movie> moviesList = new ArrayList<Movie>(); 
    ArrayAdapter<Movie> adapter; 
    static public Movie[] moviesArray; 

    protected void onCreate(Bundle savedInstanceState) 
    { 
     // TODO Auto-generated method stub 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.activity_selection); 

     ListView list = getListView(); 
     Button cancelButton = (Button) findViewById(R.id.BtnCancel); 
     cancelButton.setOnClickListener(this); 
     Button goButton = (Button) findViewById(R.id.BtnGo); 
     goButton.setOnClickListener(this); 


     adapter = new ArrayAdapter<Movie>(this, R.layout.itemlist_movie_internet, R.id.textTitle, moviesList); 

     list.setAdapter(adapter); 
     registerForContextMenu(list); 

     list.setOnItemClickListener(this); 
    } 


    @Override 
    protected void onSaveInstanceState(Bundle outState) 
    { 
     super.onSaveInstanceState(outState);  
     for (int i = 0; i < moviesArray.length; i++) 
     { 
      Movie m = moviesList.get(i); 
      outState.putString("title"+""+i,m.getSubject()); 
      outState.putString("body"+""+i,m.getBody()); 
      outState.putString("url"+""+i,m.getUrl()); 
     } 
    } 

    @Override 
    protected void onRestoreInstanceState(Bundle state) {  
     super.onRestoreInstanceState(state); 
     for (int i = 0; i < moviesArray.length; i++) 
     { 
      state.getString("title"+""+i); 
      state.getString("body"+""+i); 
      state.getString("url"+""+i);   
     } 
    } 


    @Override 
    public void onClick(View v) 
    { 
     switch (v.getId()) { 
     case R.id.BtnCancel: //Move back to main activity 
      moviesList.clear(); //PROBLEM 
      Intent intent = new Intent(InternetActivity.this, MainActivity.class);      
      startActivity(intent);   
      break; 
      default: 
      break; 
    } 
} 
} 

谢谢。

Answer 1

你没有初始化moviesArray。因此，在使用它之前将其初始化，或者在您的代码更改中获得来自moviesList的元素

moviesArray.length至moviesList.size()，即，

变化

for (int i = 0; i < moviesArray.length; i++) 

到

for (int i = 0; i < moviesList.size(); i++) 

并清除它作为

if(moviesList != null && moviesList.size() > 0) 
    moviesList.clear(); 

Answer 2

您正在查看moviesArray的长度，但尝试从moviesList中获取元素。也许你想使用moviesList.length呢？

这里是有问题的代码：

for (int i = 0; i < moviesArray.length; i++) 
    { 
     Movie m = moviesList.get(i); 

Answer 3

改变这一行前检查的moviesList大小

“moviesList.size（）“在你的代码instaed的movieArray.length

for (int i = 0; i < moviesList.size(); i++) 
     { 
      Movie m = moviesList.get(i); 
      outState.putString("title"+""+i,m.getSubject()); 
      outState.putString("body"+""+i,m.getBody()); 
      outState.putString("url"+""+i,m.getUrl()); 
     }