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alertDialog.getButton() method gives null pointer exception android

Posted by: admin February 23, 2018 Leave a comment

Questions:

Iam planing to give create 3 buttons with layout_weight=1, not interested in custom dialog.So I have written below code.It is not working.Always yes button gives me null.
Whats wrong in this code?

  AlertDialog dialog= new AlertDialog.Builder(this).create();
            dialog.setIcon(R.drawable.alert_icon);
            dialog.setTitle("title");
            dialog.setMessage("Message");
            dialog.setButton(AlertDialog.BUTTON_POSITIVE,"Yes", new DialogInterface.OnClickListener() {

                @Override
                public void onClick(DialogInterface arg0, int arg1) {
                                                }
            });
            Button yesButton = dialog.getButton(AlertDialog.BUTTON_POSITIVE);
            Log.w("Button",""+yesButton);//here getting null
            LinearLayout.LayoutParams layoutParams = new LinearLayout.LayoutParams(LayoutParams.FILL_PARENT, LayoutParams.WRAP_CONTENT, 1f);
            yesButton.setLayoutParams(layoutParams);
            dialog.show();

Regards,
Android developer.

Answers:

Take a look here for the answer : http://code.google.com/p/android/issues/detail?id=6360

As it says in comment #4 you must call show() on your dialog before you can access the buttons, they are not available beforehand. For an automatic solution on how to modify the buttons as soon as they are ready see Mickeys answer

Questions:
Answers:

This works for me :

AlertDialog alertDialog = new AlertDialog.Builder(this)
                .setMessage(message)
                .setCancelable(true)
                .setPositiveButton("Yes",
                        new DialogInterface.OnClickListener() {
                            public void onClick(DialogInterface dialog, int id) {
                            //do smthng
                        })
                .setNegativeButton("No", new DialogInterface.OnClickListener() {
                    public void onClick(DialogInterface dialog, int id) {
                        //do snthn
                    }
                }).create();

        alertDialog.setOnShowListener(new OnShowListener() {
            @Override
            public void onShow(DialogInterface dialog) {                    //
                Button positiveButton = ((AlertDialog) dialog)
                        .getButton(AlertDialog.BUTTON_POSITIVE);
                positiveButton.setBackgroundDrawable(getResources()
                        .getDrawable(R.drawable.btn_default_holo_dark));

                Button negativeButton = ((AlertDialog) dialog)
                        .getButton(AlertDialog.BUTTON_NEGATIVE);
                positiveButton.setBackgroundDrawable(getResources()
                        .getDrawable(R.drawable.btn_default_holo_dark));
            }
        });

        alertDialog.show(); 

only in this order, call alertDialog.setOnShowListener after create()

Questions:
Answers:

Thanks wieux.But for new developers understanding purpose Iam re-writing code below

    AlertDialog dialog= new AlertDialog.Builder(this).create();             
dialog.setIcon(R.drawable.alert_icon);             
dialog.setTitle("title");            
 dialog.setMessage("Message");             
dialog.setButton(AlertDialog.BUTTON_POSITIVE,"Yes", new DialogInterface.OnClickListener() {                  @Override                 
public void onClick(DialogInterface arg0, int arg1) {                                                
 }             
}); 
    dialog.show(); 
                Button yesButton = dialog.getButton(AlertDialog.BUTTON_POSITIVE);             Log.w("Button",""+yesButton);//here getting null             LinearLayout.LayoutParams layoutParams = new LinearLayout.LayoutParams(LayoutParams.FILL_PARENT, LayoutParams.WRAP_CONTENT, 1f);             yesButton.setLayoutParams(layoutParams);