Question

我的应用程序中有一个带有不同函数和clases的活动，以及那些保存位图并显示共享对话框的工作。位图保存完美，但是当我点击分享按钮时，FC会给我这个错误

Process: com.javierd.iifym, PID: 3562
                                                 java.lang.NullPointerException: Attempt to invoke virtual method 'android.app.ActivityThread$ApplicationThread android.app.ActivityThread.getApplicationThread()' on a null object reference
                                                     at android.app.Activity.startActivityForResult(Activity.java:3918)
                                                     at android.support.v4.app.BaseFragmentActivityJB.startActivityForResult(BaseFragmentActivityJB.java:48)
                                                     at android.support.v4.app.FragmentActivity.startActivityForResult(FragmentActivity.java:75)
                                                     at android.app.Activity.startActivityForResult(Activity.java:3877)
                                                     at android.support.v4.app.FragmentActivity.startActivityForResult(FragmentActivity.java:871)
                                                     at android.app.Activity.startActivity(Activity.java:4200)
                                                     at android.app.Activity.startActivity(Activity.java:4168)
                                                     at com.javierd.iifym.Utils.RewardsActivity$1.onClick(RewardsActivity.java:59)
                                                     at android.view.View.performClick(View.java:5198)
                                                     at android.view.View$PerformClick.run(View.java:21147)
                                                     at android.os.Handler.handleCallback(Handler.java:739)
                                                     at android.os.Handler.dispatchMessage(Handler.java:95)
                                                     at android.os.Looper.loop(Looper.java:148)
                                                     at android.app.ActivityThread.main(ActivityThread.java:5417)
                                                     at java.lang.reflect.Method.invoke(Native Method)
                                                     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
                                                     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)

这是活动：

    public class RewardsActivity extends AppCompatActivity {

        @Override
        protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
    }

    public void createDialog(final Bitmap bitmap, Context context){
        final Dialog dialog = new Dialog(context, android.R.style.Theme_Material_Light_Dialog_Alert);
        dialog.getWindow();
        dialog.requestWindowFeature(Window.FEATURE_NO_TITLE);
        dialog.getWindow().setBackgroundDrawable(new ColorDrawable(Color.TRANSPARENT));
        dialog.setContentView(R.layout.goals_dialog);
        ImageView imageView = (ImageView) dialog.findViewById(R.id.imageView);
        ImageButton shareButton = (ImageButton) dialog.findViewById(R.id.shareButton);
        shareButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                String imageFileName = saveBitmapAsImage(bitmap);;
                Intent share = new Intent(Intent.ACTION_SEND);
                share.setType("image/*");
                File media = new File(imageFileName);
                Uri uri = Uri.fromFile(media);
                share.putExtra(Intent.EXTRA_STREAM, uri);
                startActivity(Intent.createChooser(share, "Share to"));
            }
        });
        imageView.setImageBitmap(bitmap);
        dialog.show();
    }

    private String saveBitmapAsImage(Bitmap imageBitmap){
        String timeStamp = new SimpleDateFormat("yyyyMMdd_HHmmss", Locale.US).format(new Date());
        File myDir = new File(Environment.getExternalStorageDirectory().getAbsoluteFile().toString() + "/IIFYM");
        myDir.mkdirs();
        final File imageFileName = new File(myDir, "Reward_"+timeStamp+".jpg");
        try {
            FileOutputStream out = new FileOutputStream(imageFileName);
            imageBitmap.compress(Bitmap.CompressFormat.JPEG, 90, out);
            out.flush();
            out.close();
        } catch (Exception e) {
            e.printStackTrace();
        }
        return String.valueOf(imageFileName);
        }
    }

以这种方式从主要活动中调用该代码：

final RewardsActivity rewardsActivity = new RewardsActivity();
rewardsActivity.createDialog(imageBitmap, context);

有人可以帮我吗？非常感谢！

Answer 1

从活动开始另一项活动

您知道Intent吗？

Intent intent = new Intent(AnActivity.this,AnotherActivity.class);
startActivity(intent);

如何使用对话框

很容易找到一个对话框：像这样：

  // 1. Instantiate an AlertDialog.Builder with its constructor
  AlertDialog.Builder builder = new AlertDialog.Builder(this);

  // 2. Chain together various setter methods to set the dialog characteristics
  builder.setMessage(R.string.dialog_message)
   .setTitle(R.string.dialog_title);

 // 3. Get the AlertDialog from create()
 AlertDialog dialog = builder.create();

自定义对话框

您可以定义布局xml文件。

  // custom dialog
  final Dialog dialog = new Dialog(context);
  dialog.setContentView(R.layout.custom);
  dialog.setTitle("Title...");

   ImageView imageView = (ImageView) dialog.findViewById(R.id.imageView);
    ImageButton shareButton = (ImageButton) dialog.findViewById(R.id.shareButton);
    shareButton.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            String imageFileName = saveBitmapAsImage(bitmap);;
            Intent share = new Intent(Intent.ACTION_SEND);
            share.setType("image/*");
            File media = new File(imageFileName);
            Uri uri = Uri.fromFile(media);
            share.putExtra(Intent.EXTRA_STREAM, uri);
            startActivity(Intent.createChooser(share, "Share to"));
        }
    });

Answer 2

请仔细检查我的代码。

public class RewardsActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    // why not any layout?
}

public void createDialog(final Bitmap bitmap, Context context){
    final Dialog dialog = new Dialog(context, android.R.style.Theme_Material_Light_Dialog_Alert);
    dialog.getWindow();
    dialog.requestWindowFeature(Window.FEATURE_NO_TITLE);
    dialog.getWindow().setBackgroundDrawable(new ColorDrawable(Color.TRANSPARENT));
    dialog.setContentView(R.layout.goals_dialog);
    dialog.show();

    ImageView imageView = (ImageView) dialog.findViewById(R.id.imageView);
    ImageButton shareButton = (ImageButton) dialog.findViewById(R.id.shareButton);
    shareButton.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            String imageFileName = saveBitmapAsImage(bitmap);
            Intent share = new Intent(Intent.ACTION_SEND);
            share.setType("image/*");
            File media = new File(imageFileName);
            Uri uri = Uri.fromFile(media);
            share.putExtra(Intent.EXTRA_STREAM, uri);
            startActivity(Intent.createChooser(share, "Share to"));
        }
    });
    what this view doing here?  
    imageView.setImageBitmap(bitmap);
}

Answer 3

好的，最后很简单，我只需将startActivity(Intent.createChooser(share, "Share to"));更改为context.startActivity(Intent.createChooser(share, "Share to"));

在活动错误上共享图像错误

3 个答案:

从活动开始另一项活动

如何使用对话框

自定义对话框