Android 应用程序在后退按钮上崩溃（performResumeActivity）

Question

我的应用程序目前包含 2 个活动。 。画廊视图的主要活动 。带有 ListView 的 FriendsListActivity

当用户使用后退按钮离开 FriendsListActivity 并返回到 MAIN 活动时，在调试模式下会不断弹出以下错误。

DalvikVM[localhost:8676] 线程 [<1> main]（暂停（例外 运行时异常））
ActivityThread.performResumeActivity(IBinder, 布尔值）行：2095
ActivityThread.handleResumeActivity(IBinder, 布尔值，布尔值）行：2110
BinderProxy(ActivityThread$H).handleMessage(消息) 线路：954 ActivityThread$H(处理程序).dispatchMessage(消息) 行：99 Looper.loop() 行：123 ActivityThread.main(String[]) 行： 第3647章 对象[]、类、类[]、类、int、 布尔）行：不可用 [native 方法] Method.invoke(对象, 对象...）行：507
ZygoteInit$MethodAndArgsCaller.run() 行：839 ZygoteInit.main（字符串[]） 线路：597 NativeStart.main(String[]) 行：不是 可用[本机方法] 线程 [<8>活页夹线程#2]（正在运行）
线程 [<7>活页夹线程 #1] （运行）

使用 LogCat

03-13 22:01:10.972: 错误/Android运行时(1038)：致命 例外：主要 03-13 22:01:10.972： 错误/Android运行时(1038)： java.lang.RuntimeException：无法 恢复活动 {com.package.MAIN/com.package.MAIN.MAIN}： java.lang.NullPointerException 03-13 22:01:10.972: 错误/AndroidRuntime(1038)：位于 android.app.ActivityThread.performResumeActivity(ActivityThread.java:2095) 03-13 22:01:10.972: 错误/AndroidRuntime(1038)：位于 android.app.ActivityThread.handleResumeActivity(ActivityThread.java:2110) 03-13 22:01:10.972: 错误/AndroidRuntime(1038)：位于 android.app.ActivityThread$H.handleMessage(ActivityThread.java:954) 03-13 22:01:10.972: 错误/AndroidRuntime(1038)：位于 android.os.Handler.dispatchMessage(Handler.java:99) 03-13 22:01:10.972: 错误/AndroidRuntime(1038)：位于 android.os.Looper.loop(Looper.java:123) 03-13 22:01:10.972: 错误/AndroidRuntime(1038)：位于 android.app.ActivityThread.main(ActivityThread.java:3647) 03-13 22:01:10.972: 错误/AndroidRuntime(1038)：位于 java.lang.reflect.Method.invokeNative(本机 方法）03-13 22:01:10.972： 错误/AndroidRuntime(1038)：位于 java.lang.reflect.Method.invoke(Method.java:507) 03-13 22:01:10.972: 错误/AndroidRuntime(1038)：位于 com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839) 03-13 22:01:10.972: 错误/AndroidRuntime(1038)：位于 com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597) 03-13 22:01:10.972: 错误/AndroidRuntime(1038)：位于 dalvik.system.NativeStart.main(本机 方法）03-13 22:01:10.972： 错误/AndroidRuntime(1038)：原因： java.lang.NullPointerException 03-13 22:01:10.972: 错误/AndroidRuntime(1038)：位于 com.package.MAIN.MAIN.onResume(MAIN.java:91) 03-13 22:01:10.972: 错误/AndroidRuntime(1038)：位于 android.app.Instrumentation.callActivityOnResume(Instrumentation.java:1149) 03-13 22:01:10.972: 错误/AndroidRuntime(1038)：位于 android.app.Activity.performResume(Activity.java:3833) 03-13 22:01:10.972: 错误/AndroidRuntime(1038)：位于 android.app.ActivityThread.performResumeActivity(ActivityThread.java:2085) 03-13 22:01:10.972: 错误/Android运行时(1038): ... 10 更多

“变量”面板中的更多信息说明：
这：活动线程
e: 空指针异常
原因：NullPointerException
详细消息：空
堆栈跟踪：空
r: ActivityThread$ActivityClientRecord
活动：

一次 Eclipse 后的主要详细消息 恢复：无法恢复活动（主）

FriendsListActivity 中的代码如下所示

public class FriendsListActivity extends ListActivity {

// ===========================================================
// Fields
// ===========================================================

private ArrayList<Friend> friends = new ArrayList<Friend>();
private FriendsArrayAdapter friendsArrayAdapter;
private ListView listView;

// ===========================================================
// onCreate
// ===========================================================

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    requestWindowFeature(Window.FEATURE_NO_TITLE);
    setContentView(R.layout.friends_list);

    registerForContextMenu(getListView());
    setButtonNewFriendClickListener();
}

public void generateFriendsList() {
    FriendsService fs = new FriendsService(this);
    friends = fs.getFriendsList();

    listView = (ListView) findViewById(android.R.id.list);
    friendsArrayAdapter = new FriendsArrayAdapter(
       this, R.layout.friend_list_item, friends);
    listView.setAdapter(friendsArrayAdapter);
}

@Override
public void onCreateContextMenu(ContextMenu menu, View v, ContextMenuInfo menuInfo) {
    super.onCreateContextMenu(menu, v, menuInfo);
    MenuInflater inflater = getMenuInflater();
    inflater.inflate(R.menu.friends_context_menu, menu);
}

@Override
public boolean onContextItemSelected(MenuItem item) {
    AdapterContextMenuInfo info = (AdapterContextMenuInfo) item.getMenuInfo();
    FriendsService fs = new FriendsService(this);
    Friend f = new Friend();
    f = friends.get(info.position);
    switch (item.getItemId()) {
    case R.id.edit:
        Intent i = new Intent(this, FriendEditActivity.class);
        i.putExtra("userid", f.userId);
        startActivity(i);
        return true;
    case R.id.delete:
        fs.deleteFriend(f.userId);
        generateFriendsList();
        return true;
    default:
        return super.onContextItemSelected(item);
    }
}

// ===========================================================
// onPause
// ===========================================================

protected void onPause() {
    super.onPause();
    finish();
}

// ===========================================================
// onResume
// ===========================================================

protected void onResume() {
    super.onResume();
    generateFriendsList();
}

// ===========================================================
// onStop
// ===========================================================

protected void onStop() {
    super.onStop();
}

// ===========================================================
// onDestroy
// ===========================================================

@Override
protected void onDestroy() {
    super.onDestroy();
}

// ===========================================================
// Activity methods
// ===========================================================

private void setButtonNewFriendClickListener() {
    Button clickButton = (Button)findViewById(R.id.button_add_friend);
    clickButton.setOnClickListener(new View.OnClickListener() {
        public void onClick(View v) {
            Intent i = new Intent(v.getContext(), FriendNewActivity.class);
            startActivity(i);
        }
    });
}

AndroidManifest 如下所示

<manifest xmlns:android="http://schemas.android.com/apk/res/android"
  android:versionCode="1"
  android:versionName="1.0" package="com.package.mypackage">
<uses-permission android:name="android.permission.CAMERA" />
<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<application android:icon="@drawable/icon" android:label="@string/app_name">
    <activity android:name="com.package.mypackage.mypackage"
              android:label="@string/app_name">
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />
            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
    </activity>
     <activity android:name=".FriendsListActivity"></activity>
     <activity android:name=".FriendEditActivity"></activity>
     <activity android:name=".FriendNewActivity"></activity>
     <activity android:name=".TakePictureActivity"></activity>
     <activity android:name=".FriendsService"></activity>
     <activity android:name=".MyService"></activity>
</application>
<uses-sdk android:minSdkVersion="9" />

主要活动如下所示：

    package com.package.mypackage;

import java.util.ArrayList;

import com.package.domain.Domain;
import com.package.service.MyService;
import com.package.viewadapter.myImageAdapter;

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.view.Window;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.AdapterView.OnItemLongClickListener;
import android.widget.Button;
import android.widget.Gallery;
import android.widget.Toast;

public class myActivity extends Activity {

// ===========================================================
// Fields
// ===========================================================

private MyImageAdapter myImageAdapter;
private ArrayList<Domain> domain = new ArrayList<Domain>();

// ===========================================================
// onCreate
// ===========================================================

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    requestWindowFeature(Window.FEATURE_NO_TITLE);
    setContentView(R.layout.main);

    /* Set Buttons to listen for any click event. */
    setButtonFriendsClickListener();
    setButtonCameraClickListener();
    setButtonPreferencesClickListener();
}

// ===========================================================
// onStart
// ===========================================================

@Override
public void onStart() {
    super.onStart();

    /* Find the gallery defined in the main.xml */        
    Gallery g = (Gallery) findViewById(R.id.gallery);
    /* Show a Toast message when image is clicked */
    g.setOnItemClickListener(new OnItemClickListener() {

        @Override
        public void onItemClick(AdapterView<?> parent, View v, int position, long id) {
            MyImageAdapter image_ID = new MyImageAdapter(myActivity.this, position, null);
            if (image_ID.getItemId(position) == 0) {
                Toast test_toast = Toast.makeText(myActivity.this, "This is the New Image click", Toast.LENGTH_SHORT);
                test_toast.show();
            }
            else {
                Toast test_toast = Toast.makeText(myActivity.this, "The clicked image has image number " + image_ID.getItemId(position) + " in the imageadapter.", Toast.LENGTH_SHORT);
                test_toast.show();
            }
        }
    });

    g.setOnItemLongClickListener(new OnItemLongClickListener() {

        @Override
        public boolean onItemLongClick(AdapterView<?> parent, View v, int position, long id) {
            MyImageAdapter image_ID = new MyImageAdapter(myActivity.this, position, null);
            Toast test_toast = Toast.makeText(myActivity.this, "The long clicked image has image number " + image_ID.getItemId(position) + " in the imageadapter.", Toast.LENGTH_SHORT);
            test_toast.show();
            return true;
        }
    });
}

// ===========================================================
// onPause
// ===========================================================

protected void onPause() {
    super.onPause();
}

// ===========================================================
// onResume
// ===========================================================

protected void onResume() {
    super.onResume();
    generateMyGallery();
}

// ===========================================================
// onStop
// ===========================================================

protected void onStop() {
    super.onStop();
}

// ===========================================================
// onDestroy
// Is also called when user changes from horizontal
// to vertical orientation and back
// ===========================================================

@Override
protected void onDestroy() {
    super.onDestroy();
}

// ===========================================================
// Save and Restore UI states
// ===========================================================

@Override
protected void onRestoreInstanceState(Bundle savedInstanceState) {
    super.onRestoreInstanceState(savedInstanceState);
}

protected void onSaveInstanceState(Bundle outState) {
    super.onSaveInstanceState(outState);
}

// ===========================================================
// Main Activity methods
// ===========================================================


public void generateMyGallery() {
    MyService cs = new MyService(this);
    domain = cs.getDomainList();

    // Add the new_image drawable to the ArrayList
    Domain d = new Domain();
    d.photoLocation = "drawable";
    d.photoName = "new_image";
    d.extra1 = "no_text";
    d.extra2 = "no_text";
    domain.add(0, d);

    myImageAdapter = new MyImageAdapter(this, R.layout.text_overlay_image_view, domain);

    /* Find the gallery defined in the main.xml */        
    Gallery g = (Gallery) findViewById(R.id.gallery);
    g.setSpacing(10);

    /* Apply a new (custom) ImageAdapter to it. */
    g.setAdapter(myImageAdapter);
    g.setSelection(1);
}

private void setButtonFriendsClickListener() {
    Button clickButton = (Button)findViewById(R.id.button_friends_list);
    clickButton.setOnClickListener(new View.OnClickListener() {
        public void onClick(View v) {
            setContentView(R.layout.friends_list);

            Intent myIntent = new Intent(v.getContext(), FriendsListActivity.class);
            startActivity(myIntent);
        }
    });
}

private void setButtonCameraClickListener() {
    Button clickButton = (Button)findViewById(R.id.button_take_picture);
    clickButton.setOnClickListener(new View.OnClickListener() {
        public void onClick(View v) {
            setContentView(R.layout.take_picture);

            Intent myIntent = new Intent(v.getContext(), TakePictureActivity.class);
            startActivity(myIntent);
        }
    });
}

private void setButtonPreferencesClickListener() {
    Button clickButton = (Button)findViewById(R.id.button_preferences);
    clickButton.setOnClickListener(new View.OnClickListener() {
        public void onClick(View v) {
            Intent myIntent = new Intent(v.getContext(), MyPreferencesActivity.class);
            startActivity(myIntent);
        }
    });
    }
};

任何人都知道应用程序崩溃的原因。非常感谢任何帮助。

我确实发现，当我启动 FriendListActivity 时 finish() MAIN 活动并在关闭 FriendListActivity 时重新启动 MAIN 活动时，不会发生崩溃。然而，这基本上会重新启动应用程序，而这并不是本意。

---

谢谢大家，我的问题已经解决了。这就是我所做的。
。当将所有与画廊相关的操作移至 onCreate 时，崩溃不再发生。但返回主活动后，该活动并未显示。
。然后，我将所有 onCreate（除了 super）、generateGallery 和 onStart() 移至 onResume。现在效果很好！

Answer 1

为什么要调用onPause() finish()？

你试过把它注释掉吗？

这个朋友服务是什么？

可能它会导致您的异常。

UPD：

我想说，移动generateMyGallery();从 onResume 到 onCreate。因为每次用户从另一个活动返回时 onResume 都会被调用。所以generateMyGallery()也是如此