How to create alert in android

Some times it is a need to popup a message as warning message or alert message for the user and also give option to the user to close that popup after reading the message.
So following the below set of code you can do it easily.

1. Initialising.

AlertDialog.Builder alert = new AlertDialog.Builder(this);
alert.setTitle("Test Title").setPositiveButton("ok", new OnClickListener() {
    @Override
    public void onClick(DialogInterface dialog, int which) {
        dialog.dismiss();                        
    }
});

2. Execution

alert.setMessage("Your Warning Message").show();