android返回值意图的最佳实践

Question

i have 2 activities, one is a Database of exercises and the other one is new exercise creator

in this function i create a new class of an exercise, i want to return the new class to the Database activity.

and when creating a new exercise delete this activity and create a new one which will create a new Exercise class.

public void onClickDone(View view)
{
    EditText editText = (EditText) findViewById(R.id.edit_name);
    String name = editText.getText().toString();
    editText = (EditText) findViewById(R.id.edit_description);
    String description = editText.getText().toString();
    editText = (EditText) findViewById(R.id.edit_reptitons);
    EditText editSets = (EditText) findViewById(R.id.edit_sets);
    EditText editTimeBetweenSets = (EditText) findViewById(R.id.edit_time_between_sets_);
    int reptitons = 0 ;
    int sets = 0 ;
    int timeBetweenSets = 0;
    try
    {
        reptitons = Integer.parseInt(editText.getText().toString());
        sets = Integer.parseInt(editSets.getText().toString());
        timeBetweenSets = Integer.parseInt(editTimeBetweenSets.getText().toString());
    }
    catch(NumberFormatException ex)
    {
        AlertDialog.Builder dlgAlert  = new AlertDialog.Builder(this);

        dlgAlert.setMessage("please check you input");
        dlgAlert.setTitle("Wrong Input");
        dlgAlert.setPositiveButton("OK", null);
        dlgAlert.setCancelable(true);
        dlgAlert.create().show();
    }
    _excercise = new Exercise(name, description, reptitons, sets, timeBetweenSets);
}

what is a the best practice for 2 activities to create a class, save it to a list and create a new one when pressing the "create new exercise button" again?

or maybe i should create the instance of the class inside the add exercise activity?

Answer 1

First of all, you're creating objects, not classes.

You can stop Activities using finish(); which should return you to your previous activity.

If you want your second Activity to send Data to the first activity maybe check out startActivityForResult . Check out this topic.

Answer 2

From your FirstActivity call the SecondActivity using startActivityForResult() method

For example:

Intent i = new Intent(this, SecondActivity.class);
startActivityForResult(i, 1);

In your SecondActivity set the data which you want to return back to FirstActivity. If you don't want to return back, don't set any.

For example:

In secondActivity if you want to send back data:

Intent returnIntent = new Intent();
returnIntent.putExtra("result",result);
setResult(RESULT_OK,returnIntent);
finish();

If you don't want to return data:

Intent returnIntent = new Intent();
setResult(RESULT_CANCELED, returnIntent);
finish();

Now in your FirstActivity class write following code for the onActivityResult() method.

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

{

    if (requestCode == 1) {
        if(resultCode == RESULT_OK){
            String result=data.getStringExtra("result");
        }
        if (resultCode == RESULT_CANCELED) {
            //Write your code if there's no result
        }
    }
}//onActivityResult