Question

我的问题是：我是Android编程的新手，我创建了一个新的应用程序，当我按下按钮在下面启动此活动时，它崩溃了。当我调试它时，它说onCreate（）有一个空包。我该如何解决？我不了解活动的其他类别所以请使用详细信息，提前感谢！

这是我的代码：

@Override
public void onCreate(final Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.my_requests);


        GridView gridview = (GridView) findViewById(R.id.gridview);
        gridview.setAdapter(new ImageAdapter(this));


    gridview.setOnItemClickListener(new AdapterView.OnItemClickListener() {


        public void onItemClick(AdapterView<?> parent, View v, int position, long id) {
            AlertDialog.Builder builder = new AlertDialog.Builder(my_requests.this);
            switch (position){
                case 0: builder.setMessage("You Chose Television, Wait");
                    break;
                case 1: builder.setMessage("You Chose Cookie, Wait");
                    break;
                case 2: builder.setMessage("You Chose Toilet, Wait");
                    break;
                case 3: builder.setMessage("You Chose Toys, Wait");
                    break;
                case 4: builder.setMessage("You Chose Lunch, Wait");
                    break;
                case 5:builder.setMessage("You Chose Water, Wait");
                    break;
            }
            builder.setNeutralButton("OK", new DialogInterface.OnClickListener() {
                public void onClick(DialogInterface dialog, int id) {
                    // User cancelled the dialog
                }
            });
            AlertDialog dialog = builder.create();
            dialog.show();

        }
    });
    super.onSaveInstanceState(savedInstanceState);
}

编辑::以下添加的LOGCAT

02-24 14:53:00.642  17789-17789/com.tiktaktikapps.Gimmie_ D/AndroidRuntime﹕ Shutting down VM
    --------- beginning of crash
02-24 14:53:00.647  17789-17789/com.tiktaktikapps.Gimmie_ E/AndroidRuntime﹕ FATAL EXCEPTION: main
    Process: com.tiktaktikapps.Gimmie_, PID: 17789
    java.lang.RuntimeException: Unable to start activity ComponentInfo{com.tiktaktikapps.Gimmie_/com.tiktaktikapps.Gimmie_.my_requests}: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.GridView.setAdapter(android.widget.ListAdapter)' on a null object reference
            at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2305)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2367)
            at android.app.ActivityThread.access$800(ActivityThread.java:148)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1283)
            at android.os.Handler.dispatchMessage(Handler.java:102)
            at android.os.Looper.loop(Looper.java:135)
            at android.app.ActivityThread.main(ActivityThread.java:5274)
            at java.lang.reflect.Method.invoke(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:372)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:909)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:704)
     Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.GridView.setAdapter(android.widget.ListAdapter)' on a null object reference
            at com.tiktaktikapps.Gimmie_.my_requests.onCreate(my_requests.java:49)
            at android.app.Activity.performCreate(Activity.java:5977)
            at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1105)
            at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2258)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2367)
            at android.app.ActivityThread.access$800(ActivityThread.java:148)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1283)
            at android.os.Handler.dispatchMessage(Handler.java:102)
            at android.os.Looper.loop(Looper.java:135)
            at android.app.ActivityThread.main(ActivityThread.java:5274)
            at java.lang.reflect.Method.invoke(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:372)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:909)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:704)

Answer 1

引起：java.lang.NullPointerException：尝试调用虚方法＆＃39; void android.widget.GridView.setAdapter（android.widget.ListAdapter）＆＃39;在空对象引用上

您发布的logcat摘录与null Bundle无关，而是表示R.id.gridview

中未找到R.layout.my_requests

检查您的xml文件，查看错误，拼写错误，大写差异，并确保使用您想要的那些。然后清理你的项目（一些工具版本不擅长选择xml更改）并重新部署。

Answer 2

删除最后一行 -

super.onSaveInstanceState(savedInstanceState);

应该从onSaveInstanceState（）调用它。

onCreate（savedInstanceState）savedInstanceState为NULL

2 个答案: