Android 从McClickListener调用搜索对话框

我有个奇怪的问题。我正在尝试在我的应用程序中实现搜索。如果我按下搜索按钮或从onStart功能调用onSearchRequested，搜索屏幕将显示。但如果我从onItemClick侦听器的onItemClick函数调用OnSearchRequested，我会得到一个NullPointerException。我还尝试获取搜索管理器的实例，并直接调用startSearch函数，但也失败了

我想这个人也有同样的问题，没有得到回答，但我不确定

以下是我的OnStart方法：

@Override
    protected void onStart() {  
        super.onStart();
        this.setContentView(R.layout.mainactivity);
        ListView lv = (ListView)this.findViewById(R.id.MainActivityList);

        lv.setAdapter(new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1, actions));
        onSearchRequested();   //This works...
        lv.setOnItemClickListener(new OnItemClickListener(){

            public void onItemClick(AdapterView<?> parent, View view, int position, long id) {

                Intent i = null;
                Context c = MainActivity.this;
                //position is the index of actions above.
                switch(position)
                {
                case 0:
                    i = new Intent(c,MainCategoryActivity.class);
                    break;
                case 1:
                    //SearchManager sm = (SearchManager) MainActivity.this.getSystemService(Context.SEARCH_SERVICE);
                    //sm.startSearch(null, false, new ComponentName(MainActivity.this, MainActivity.class) , null, false);


                    onSearchRequested();   //NullPointerException
                    break;
                case 2:
                    i = new Intent(c,SelectCityActivity.class);
                    break;
                case 3:
                    i = new Intent(c,SavedSearchesActivity.class);
                    break;              
                }

                c.startActivity(i);


            }});

    }

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我是个白痴。请注意，在onItemCLick处理程序中，如果选择了1，则会调用onSearchRequested，然后断开开关，最后调用c.startActivityi，并且i被初始化为null。这就是空指针的来源。对不起，新手犯的错误。

---

-James

我还尝试创建一个处理程序，并让onclick事件向它传递一条消息以请求搜索对话框，但它也有同样的问题nullpointer。所以你现在得到了它。。。为未来的发展做最好的准备…：

      06-28 16:09:22.368: E/AndroidRuntime(1702): FATAL EXCEPTION: main
      06-28 16:09:22.368: E/AndroidRuntime(1702): java.lang.NullPointerException
      06-28 16:09:22.368: E/AndroidRuntime(1702):   at android.app.Instrumentation.execStartActivity(Instrumentation.java:1378)
      06-28 16:09:22.368: E/AndroidRuntime(1702):   at android.app.Activity.startActivityForResult(Activity.java:3190)
      06-28 16:09:22.368: E/AndroidRuntime(1702):   at android.app.Activity.startActivity(Activity.java:3297)
      06-28 16:09:22.368: E/AndroidRuntime(1702):   at com.TheGreensheet.GreensheetReader.MainActivity$1.onItemClick(MainActivity.java:47)
      06-28 16:09:22.368: E/AndroidRuntime(1702):   at android.widget.AdapterView.performItemClick(AdapterView.java:292)
      06-28 16:09:22.368: E/AndroidRuntime(1702):   at android.widget.AbsListView.performItemClick(AbsListView.java:1058)
      06-28 16:09:22.368: E/AndroidRuntime(1702):   at android.widget.AbsListView$PerformClick.run(AbsListView.java:2514)
      06-28 16:09:22.368: E/AndroidRuntime(1702):   at android.widget.AbsListView$1.run(AbsListView.java:3168)
      06-28 16:09:22.368: E/AndroidRuntime(1702):   at android.os.Handler.handleCallback(Handler.java:605)
      06-28 16:09:22.368: E/AndroidRuntime(1702):   at android.os.Handler.dispatchMessage(Handler.java:92)
      06-28 16:09:22.368: E/AndroidRuntime(1702):   at android.os.Looper.loop(Looper.java:137)
      06-28 16:09:22.368: E/AndroidRuntime(1702):   at android.app.ActivityThread.main(ActivityThread.java:4424)
      06-28 16:09:22.368: E/AndroidRuntime(1702):   at java.lang.reflect.Method.invokeNative(Native Method)
      06-28 16:09:22.368: E/AndroidRuntime(1702):   at java.lang.reflect.Method.invoke(Method.java:511)
      06-28 16:09:22.368: E/AndroidRuntime(1702):   at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
      06-28 16:09:22.368: E/AndroidRuntime(1702):   at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
      06-28 16:09:22.368: E/AndroidRuntime(1702):   at dalvik.system.NativeStart.main(Native Method)