The easiest (but also most ugly) would be an edittext with inputtype number.
But making a number picker from scratch isnt that hard.
You just need a Textview which takes a variable as text. Add a + and - button which increment/decrement the variable and call Textview.setText(variable)
counter = 0;
add = (Button) findViewById(R.id.bAdd);
sub = (Button) findViewById(R.id.bSub);
display = (TextView) findViewById(R.id.tvDisplay);
add.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
counter++;
display.setText( "" + counter);
}
});
sub.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
counter--;
display.setText( "" + counter);
}
});
}
in xml just add 2 buttons with id bAdd and bSub and a textview with id tvDisplay and arrange them like you want