android return activity extras returns null

When trying to pass data from one activity to another it works fine in one direction parent>>child. But the return path child>>parent crashes I think with a null pointer exception. Now I can trap the null easy enough but cant figure out where my passed int is getting lost?

How do you debug this type of problem – any insight etc…

the crash occurs of the line: int binVal = extras.getInt("binVal");

// when leaving the child开发者_开发百科 activity
OnClickListener mReturnListener = new OnClickListener() {
    public void onClick(View v) {
        Intent intent = getIntent();
        intent.putExtra("binVal", (int)binVal);
        setResult(Activity.RESULT_OK, intent);
        finish();
    }
};  



//on return to the parent actvity
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
    switch (requestCode) { 
    case SET_BIN_TEMP:
        if (resultCode == RESULT_OK) {           
            Bundle extras = getIntent().getExtras();
            if (extras == null)
                Toast.makeText(PilotActivity.this, "null returned!", Toast.LENGTH_SHORT).show();
            else {
                 int binVal = extras.getInt("binVal");
                 text.setText(Integer.toString(binVal));
             }
        }
        return;
    }
}

Look at your onActivityResult(...) parameters...

protected void onActivityResult(int requestCode, int resultCode, Intent data)

When an Activity that has been started with startActivityForResult returns, the Intent returned is the parameter data.

In your 'parent' Activity you are using its getIntent() method which returns the Intent (if any) which started the Activity originally.

Instead of...

Bundle extras = getIntent().getExtras();

...you should use...

Bundle extras = data.getExtras();

I had problems with this in the past and had to do something like the code sample below:

OnClickListener mReturnListener = new OnClickListener() {
    public void onClick(View v) {
        Intent intent = getIntent();
        intent.putExtra("binVal", (int)binVal);

        if (getParent() == null)
            YourActivity.this.setResult(Activity.RESULT_OK, intent);
        else
            YourActivity.this.getParent().setResult(Activity.RESULT_OK, intent);

        finish();
    }
};