从GridView返回图像作为活动结果，接收的处理程序错误

Question

当前使用本教程http://www.androidhive.info/2012/02/android-gridview-layout-tutorial/用于gridview。我正在尝试操纵它，以便它将所选图片作为活动结果返回到我的主要活动中，以便我可以将其设置为imageview，然后在其他某些任务中稍后使用所选图像。

我遇到的问题是将结果恢复到我的主要活动中，我会遇到未识别的处理程序错误。是的，我是个菜鸟，所以一定要指出我的错误和关于我出错的地方的任何解释总是有助于学习。

我最初呼吁startActivityForresult

Button.OnClickListener buttonClickListener4 = new Button.OnClickListener() {
  public void onClick(View ChoosePictureButton) {
    Intent intent = new Intent(PictureActivity.this, PicPicker2.class);
    startActivityForResult(intent, 2);
      } 
    };

应该返回单击图像时结果的活动

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.grid_layout);
    GridView gridView = (GridView) findViewById(R.id.grid_view);
    // Instance of ImageAdapter Class
    gridView.setAdapter(new ImageAdapter(this));
    /**
     * On Click event for Single Gridview Item
     * */
    gridView.setOnItemClickListener(new OnItemClickListener() {
        @Override
        public void onItemClick(AdapterView<?> parent, View v,
                int position, long id) {
            // Sending image id to PictureActivity
            Intent i = new Intent();
            // passing array index
            i.putExtra("id", position);
            setResult(Activity.RESULT_OK, i);
            finish();
        }
    });
}

}

我希望我的原始活动能够捕捉结果

  public void onActivityResult(int reqCode, int resultCode, Intent data) {
    super.onActivityResult(reqCode, resultCode, data);
        if (resultCode == Activity.RESULT_OK) {
             if(reqCode == 1) { for another activity result.... }           
              else if (reqCode == 2) {
                Intent i = getIntent();
                // Selected image id
                int position = i.getExtras().getInt("id");
                ImageAdapter imageAdapter = new ImageAdapter(this);
                ChosenImageView.setImageResource(imageAdapter.mThumbIds[position]);
              }
            }
        }   

是的，我可能屠宰了它，但是应该对我的尝试有一个了解。我的logcat在下面。

10-21 16:41:30.839: E/AndroidRuntime(4978): Uncaught handler: thread main exiting due to uncaught exception
10-21 16:41:30.869: E/AndroidRuntime(4978): java.lang.RuntimeException: Failure delivering result ResultInfo{who=null, request=2, result=-1, data=Intent { (has extras) }} to activity {jtek.industries.com/jtek.industries.com.PictureActivity}: java.lang.NullPointerException
10-21 16:41:30.869: E/AndroidRuntime(4978):     at android.app.ActivityThread.deliverResults(ActivityThread.java:3329)
10-21 16:41:30.869: E/AndroidRuntime(4978):     at android.app.ActivityThread.handleSendResult(ActivityThread.java:3371)
10-21 16:41:30.869: E/AndroidRuntime(4978):     at android.app.ActivityThread.access$2700(ActivityThread.java:119)
10-21 16:41:30.869: E/AndroidRuntime(4978):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1893)
10-21 16:41:30.869: E/AndroidRuntime(4978):     at android.os.Handler.dispatchMessage(Handler.java:99)
10-21 16:41:30.869: E/AndroidRuntime(4978):     at android.os.Looper.loop(Looper.java:123)
10-21 16:41:30.869: E/AndroidRuntime(4978):     at android.app.ActivityThread.main(ActivityThread.java:4363)
10-21 16:41:30.869: E/AndroidRuntime(4978):     at java.lang.reflect.Method.invokeNative(Native Method)
10-21 16:41:30.869: E/AndroidRuntime(4978):     at java.lang.reflect.Method.invoke(Method.java:521)
10-21 16:41:30.869: E/AndroidRuntime(4978):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:860)
10-21 16:41:30.869: E/AndroidRuntime(4978):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:618)
10-21 16:41:30.869: E/AndroidRuntime(4978):     at dalvik.system.NativeStart.main(Native Method)
10-21 16:41:30.869: E/AndroidRuntime(4978): Caused by: java.lang.NullPointerException
10-21 16:41:30.869: E/AndroidRuntime(4978):     at jtek.industries.com.PictureActivity.onActivityResult(PictureActivity.java:138)
10-21 16:41:30.869: E/AndroidRuntime(4978):     at android.app.Activity.dispatchActivityResult(Activity.java:3828)
10-21 16:41:30.869: E/AndroidRuntime(4978):     at android.app.ActivityThread.deliverResults(ActivityThread.java:3325)

Answer 1

在您的onActivityResult() -Method中，有什么原因是您使用getIntent() -Method的意图？

我认为您得到的意图不持有结果数据，而是启动活动的意图（可能是null）。因此，在int position = i.getExtras().getInt("id")行中，i将为null，而NPE被抛出。

查看使用提供的意图数据参数解决您的问题。