Question

我正在尝试使用片段，并在MainActivity中的方法中启动一个活动。我的代码MainActiviy.java是：

    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

//      Setting up toolbar here

        toolbar = (Toolbar) findViewById(R.id.app_bar);
        toolbar.setLogo(R.mipmap.ic_launcher);
        toolbar.setTitle(" Daily Qura'n Verses");
        setSupportActionBar(toolbar);
//      add tabs in the mainactivity

        super.onPostResume();
        mTabHost = (FragmentTabHost) findViewById(android.R.id.tabhost);
        mTabHost.setup(this, getSupportFragmentManager(), R.id.realtabcontent);

        mTabHost.addTab(mTabHost.newTabSpec("tab1").setIndicator("Today's Verse"),
                TodayVerse.class, null);
        mTabHost.addTab(mTabHost.newTabSpec("tab2").setIndicator("Today's Chapter"),
                TodayChapter.class, null);
        mTabHost.addTab(mTabHost.newTabSpec("tab3").setIndicator("Complete Qur'an"),
                completeQuran.class, null);
//      set Alarm for notification creation
        createNotification();


    }

其中的方法是：

 public boolean onOptionsItemSelected(MenuItem item) {
       switch (item.getItemId()) {
           case R.id.search_bar:
                startActivity(new Intent(this, SearchResultsActivity.class));
            default:
                return super.onOptionsItemSelected(item);
        }
    }

但是，当我点击search_bar时，我收到错误。请帮我解决这个问题。

编辑1：

Log cat是：

8435-8435/com.example.shiza.dailyquranverses E/AndroidRuntime﹕ FATAL  EXCEPTION: main
    java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.shiza.dailyquranverses/com.example.shiza.dailyquranverses.SearchResultsActivity}:
java.lang.NullPointerException
            at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1956)
           at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1981)
            at android.app.ActivityThread.access$600(ActivityThread.java:123)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1147)
            at android.os.Handler.dispatchMessage(Handler.java:99)
            at android.os.Looper.loop(Looper.java:137)
            at android.app.ActivityThread.main(ActivityThread.java:4424)
            at java.lang.reflect.Method.invokeNative(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:511)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
            at dalvik.system.NativeStart.main(Native Method)
     Caused by: java.lang.NullPointerException
            at com.example.shiza.dailyquranverses.SearchResultsActivity.onCreate(SearchResultsActivity.java:24)
            at android.app.Activity.performCreate(Activity.java:4492)
            at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1049)
            at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1920)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1981)
            at android.app.ActivityThread.access$600(ActivityThread.java:123)
             at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1147)
             at android.os.Handler.dispatchMessage(Handler.java:99)
            at android.os.Looper.loop(Looper.java:137)
             at android.app.ActivityThread.main(ActivityThread.java:4424)
            at java.lang.reflect.Method.invokeNative(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:511)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
             at dalvik.system.NativeStart.main(Native Method)

Answer 1

com.example.shiza.dailyquranverses.SearchResultsActivity.onCreate(SearchResultsA‌ctivity.java 此行显示您的搜索值存在一些问题，导致空指针异常，请检查您的值

无法从包含片段的主活动启动活动

1 个答案: