java - 第一个 Intent 是有效，第二个 Intent 是让我崩溃

Question

接收方有两个 Intent ，它们从同一 Activity 调用并将数据发送到不同的 Activity 。第二个 Intent 不起作用。第一个是这样的。我不明白为什么。所有 Activity 和 list 似乎都是正确的。

//second intent on senders side    
        public void onItemSelected(AdapterView<?> arg0, View users, int i,
                        long l) {
                    FILENAME = (adapter.getItem(i)).toString();

            Bundle viewBag2 = new Bundle();
                        viewBag2.putString("profile_name", FILENAME);
                        Intent b = new Intent(OptionsMenu.this, CoreActivity.class);
                        b.putExtras(viewBag2);  
                        startActivity(b);
              }


    //second intent on receiver side

        private void Data_transfer() {
        Bundle gotbasket2 = getIntent().getExtras();
                profileName = gotbasket2.getString("profile_name");
        }

    //first (working intent) on senders side
        public void onClick(View v) {
                    Bundle viewBag = new Bundle();
                    viewBag.putString("spinner_result", s);
    a.putExtras(viewBag);
    }



    //first (working intent) on receiver side
        private void Data_transfer() {
            // TODO Auto-generated method stub
            Bundle gotbasket = getIntent().getExtras();
            x = gotbasket.getString("spinner_result");
    }

下面是附加的 logcat。

 06-26 20:22:09.787: D/AndroidRuntime(1802): Shutting down VM
    06-26 20:22:09.787: W/dalvikvm(1802): threadid=1: thread exiting with uncaught exception (group=0x40015560)
    06-26 20:22:09.847: E/AndroidRuntime(1802): FATAL EXCEPTION: main
    06-26 20:22:09.847: E/AndroidRuntime(1802): java.lang.RuntimeException: Unable to start activity ComponentInfo{mioc.diver/mioc.diver.CoreActivity}: java.lang.NullPointerException
    06-26 20:22:09.847: E/AndroidRuntime(1802):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1647)
    06-26 20:22:09.847: E/AndroidRuntime(1802):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1663)
    06-26 20:22:09.847: E/AndroidRuntime(1802):     at android.app.ActivityThread.access$1500(ActivityThread.java:117)
    06-26 20:22:09.847: E/AndroidRuntime(1802):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:931)
    06-26 20:22:09.847: E/AndroidRuntime(1802):     at android.os.Handler.dispatchMessage(Handler.java:99)
    06-26 20:22:09.847: E/AndroidRuntime(1802):     at android.os.Looper.loop(Looper.java:123)
    06-26 20:22:09.847: E/AndroidRuntime(1802):     at android.app.ActivityThread.main(ActivityThread.java:3683)
    06-26 20:22:09.847: E/AndroidRuntime(1802):     at java.lang.reflect.Method.invokeNative(Native Method)
    06-26 20:22:09.847: E/AndroidRuntime(1802):     at java.lang.reflect.Method.invoke(Method.java:507)
    06-26 20:22:09.847: E/AndroidRuntime(1802):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
    06-26 20:22:09.847: E/AndroidRuntime(1802):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
    06-26 20:22:09.847: E/AndroidRuntime(1802):     at dalvik.system.NativeStart.main(Native Method)
    06-26 20:22:09.847: E/AndroidRuntime(1802): Caused by: java.lang.NullPointerException
    06-26 20:22:09.847: E/AndroidRuntime(1802):     at mioc.diver.CoreActivity.Data_transfer(CoreActivity.java:189)
    06-26 20:22:09.847: E/AndroidRuntime(1802):     at mioc.diver.CoreActivity.onCreate(CoreActivity.java:88)
    06-26 20:22:09.847: E/AndroidRuntime(1802):     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
    06-26 20:22:09.847: E/AndroidRuntime(1802):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1611)
    06-26 20:22:09.847: E/AndroidRuntime(1802):     ... 11 more

Answer 1

首先，您不需要每次想要在 Intent 中添加额外内容时都创建一个新的 bundle 。你可以这样做:

Intent b = new Intent(OptionsMenu.this, CoreActivity.class);
b.putExtra(key, value);

其次，方法名称不应以大写字母开头，如 Google Java Style Guide 中所述。 .

最后，您似乎在 Data_transfer() 中收到 NullPointerException，这意味着您的 Activity 的第 189 行(可能是 FILENAME)有一个 null 变量。