从当前活动返回时，显示上一个活动的按钮

Question

I want to visible a edit button on my previous activity by going back using back button. But when I am using

        @Override
            public void onClick(View arg0) {
                // finish the current activity
                finish();

            }

on my current activity, it is going back to previous activity, but edit button doesn't become visible.

If I am using onResume on previous activity

@Override
    protected void onResume() {
        super.onResume();
        btnEdit.setVisibility(View.VISIBLE);

    }

then it's always visible, no matter if the activity is resuming or created for the first time.

I am new in Android development, please help me to solve this problem.

Answer 1

您可以创建一个布尔变量，完成后可以将其设置为true，并在onResume方法中对此布尔值进行检查

Answer 2

Override onRestart() method

@Override
protected void onRestart () {
    super.onResume();
    btnEdit.setVisibility(View.VISIBLE);

}

Or start Activity with

startActivityForResult (Intent intent, int requestCode)

method and override

@Override
protected void onActivityResult (int requestCode, int resultCode, Intent data){
    super.onActivityResult (requestCode,resultCode,data);
    btnEdit.setVisibility(View.VISIBLE);

}

Answer 3

Ok,

When you start the Activity, instead of startActivity(intent) use startActivityForResult(intent, 1989) (The 1989 can be whatever int you want).

When you return from the new Activity, before calling finish() do the following:

        Intent returnIntent = new Intent();
        returnIntent.putExtra("resultBool", true);

        //Null checks, not strictly neccescary 

            if (getParent() == null)
            {
                setResult(Activity.RESULT_OK, returnIntent);
            }
            else
            {
                getParent().setResult(Activity.RESULT_OK, returnIntent);
            }

    finish();

Then in your first Activity override onActivityResult() like so:

 @Override
protected void onActivityResult(int requestCode, int resultCode, Intent data)
        {
            // The int you initially used
            if (requestCode == 1989)
            {
                if (resultCode == RESULT_OK)
                {
                    boolean result = data.getBooleanExtra("resultBool", false)

                    if (result)
                      //Show the button now

                }
            }
    }