android 内存溢出 add,java - 当我引用ArrayList.add方法时，Android应用程序在启动时崩溃 - 堆栈内存溢出...

这是我的MainActivity的完整代码。 如您所见，我仅添加了2行：

ArrayList y = null;

y.add(new String("buggy")); // When I remove this line it works

当我注释掉y.add()时，应用程序不会崩溃。

我的问题是：为什么使用y.add()会导致程序失败？

移动设备是运行Android 2.3.4的Samsung Galaxy Mini S5570。

这是完整的代码，然后是LogCat：

package com.testbug;

import javax.*;

import java.util.*;

import android.os.Bundle;

import android.app.Activity;

import android.view.Menu;

import android.view.MenuItem;

import android.support.v4.app.NavUtils;

public class MainActivity extends Activity {

@Override

public void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.activity_main);

//

// Only these 2 lines added by me. The rest is automatically generated in Eclipse.

ArrayList y = null;

y.add(new String("buggy")); // When I remove this line it works

}

@Override

public boolean onCreateOptionsMenu(Menu menu) {

getMenuInflater().inflate(R.menu.activity_main, menu);

return true;

}

}

堆栈跟踪：

07-05 21:01:37.919: D/AndroidRuntime(32067): Shutting down VM

07-05 21:01:37.919: W/dalvikvm(32067): threadid=1: thread exiting with uncaught exception (group=0x40018578)

07-05 21:01:37.929: E/AndroidRuntime(32067): FATAL EXCEPTION: main

07-05 21:01:37.929: E/AndroidRuntime(32067): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.testbug/com.testbug.MainActivity}: java.lang.NullPointerException

07-05 21:01:37.929: E/AndroidRuntime(32067): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1651)

07-05 21:01:37.929: E/AndroidRuntime(32067): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1667)

07-05 21:01:37.929: E/AndroidRuntime(32067): at android.app.ActivityThread.access$1500(ActivityThread.java:117)

07-05 21:01:37.929: E/AndroidRuntime(32067): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:935)

07-05 21:01:37.929: E/AndroidRuntime(32067): at android.os.Handler.dispatchMessage(Handler.java:99)

07-05 21:01:37.929: E/AndroidRuntime(32067): at android.os.Looper.loop(Looper.java:130)

07-05 21:01:37.929: E/AndroidRuntime(32067): at android.app.ActivityThread.main(ActivityThread.java:3687)

07-05 21:01:37.929: E/AndroidRuntime(32067): at java.lang.reflect.Method.invokeNative(Native Method)

07-05 21:01:37.929: E/AndroidRuntime(32067): at java.lang.reflect.Method.invoke(Method.java:507)

07-05 21:01:37.929: E/AndroidRuntime(32067): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:867)

07-05 21:01:37.929: E/AndroidRuntime(32067): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:625)

07-05 21:01:37.929: E/AndroidRuntime(32067): at dalvik.system.NativeStart.main(Native Method)

07-05 21:01:37.929: E/AndroidRuntime(32067): Caused by: java.lang.NullPointerException

07-05 21:01:37.929: E/AndroidRuntime(32067): at com.testbug.MainActivity.onCreate(MainActivity.java:20)

07-05 21:01:37.929: E/AndroidRuntime(32067): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)

07-05 21:01:37.929: E/AndroidRuntime(32067): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1615)

07-05 21:01:37.929: E/AndroidRuntime(32067): ... 11 more