i'm a completely noob with java code but i want to learn. Now i set a keypad ,to do this i entered 3 orizzontal Linearlayout and in each one of it i entered 3 Buttons,all this in activity_main.xml like this
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/LinearLayout1"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context=".MainActivity" >
<EditText
    android:id="@+id/editText1"
    android:layout_width="286dp"
    android:layout_height="wrap_content"
    android:layout_marginTop="14dp"
    android:ems="10"
    android:inputType="numberPassword" >
    <requestFocus />
</EditText>
<LinearLayout android:orientation="horizontal" 
             android:layout_width="fill_parent" 
             android:layout_height="54.0dip" 
             android:layout_marginLeft="2.0dip" 
             android:layout_marginRight="2.0dip">
   <Button   android:textStyle="bold" 
             android:id="@+id/one"
             android:layout_width="0.0sp" 
             android:layout_height="fill_parent" 
             android:layout_marginLeft="2.0dip" 
             android:layout_marginRight="2.0dip" 
             android:layout_weight="1.0" />
    <Button  android:textStyle="bold" 
             android:id="@+id/two"
             android:layout_width="0.0sp" 
             android:layout_height="fill_parent" 
             android:layout_marginLeft="2.0dip" 
             android:layout_marginRight="2.0dip" 
             android:layout_weight="1.0" />
    <Button  android:textStyle="bold"
             android:id="@+id/three"
             android:layout_width="0.0sp" 
             android:layout_height="fill_parent" 
             android:layout_marginLeft="2.0dip" 
             android:layout_marginRight="2.0dip" 
             android:layout_weight="1.0" />
 </LinearLayout>
 <LinearLayout android:orientation="horizontal" 
             android:layout_width="fill_parent" 
             android:layout_height="54.0dip" 
             android:layout_marginLeft="2.0dip" 
             android:layout_marginRight="2.0dip">
    <Button  android:textStyle="bold"
             android:id="@+id/four"
             android:layout_width="0.0sp" 
             android:layout_height="fill_parent" 
             android:layout_marginLeft="2.0dip" 
             android:layout_marginRight="2.0dip" 
             android:layout_weight="1.0" />
    <Button  android:textStyle="bold" 
             android:id="@+id/five"
             android:layout_width="0.0sp" 
             android:layout_height="fill_parent" 
             android:layout_marginLeft="2.0dip" 
             android:layout_marginRight="2.0dip" 
             android:layout_weight="1.0" />
    <Button  android:textStyle="bold"
             android:id="@+id/six"
             android:layout_width="0.0sp" 
             android:layout_height="fill_parent" 
             android:layout_marginLeft="2.0dip" 
             android:layout_marginRight="2.0dip" 
             android:layout_weight="1.0" />
</LinearLayout>
<LinearLayout android:orientation="horizontal" 
             android:layout_width="fill_parent" 
             android:layout_height="54.0dip" 
             android:layout_marginLeft="2.0dip" 
             android:layout_marginRight="2.0dip">
    <Button  android:textStyle="bold"
             android:id="@+id/seven" 
             android:layout_width="0.0sp" 
             android:layout_height="fill_parent" 
             android:layout_marginLeft="2.0dip" 
             android:layout_marginRight="2.0dip" 
             android:layout_weight="1.0" />
    <Button  android:textStyle="bold" 
             android:id="@+id/eight"
             android:layout_width="0.0sp" 
             android:layout_height="fill_parent" 
             android:layout_marginLeft="2.0dip" 
             android:layout_marginRight="2.0dip" 
             android:layout_weight="1.0" />
    <Button  android:textStyle="bold"
             android:id="@+id/nine"
             android:layout_width="0.0sp" 
             android:layout_height="fill_parent" 
             android:layout_marginLeft="2.0dip" 
             android:layout_marginRight="2.0dip" 
             android:layout_weight="1.0" />
</LinearLayout>
</LinearLayout>
each background of Button is definite by a xml in drawable like this
<?xml version="1.0" encoding="utf-8"?>
<selector
 xmlns:android="http://schemas.android.com/apk/res/android">   
<item android:state_window_focused="false" android:state_enabled="true" android:drawable="@drawable/btn_default_normal_holo_dark" />
<item android:state_window_focused="false" android:state_enabled="false" android:drawable="@drawable/btn_default_normal_disable" />
<item android:state_pressed="true" android:drawable="@drawable/btn_default_pressed_holo_dark" />
<item android:state_focused="true" android:state_enabled="true" android:drawable="@drawable/btn_default_selected" />
<item android:state_enabled="true" android:drawable="@drawable/btn_default_normal_holo_dark" />
<item android:state_focused="true" android:drawable="@drawable/btn_default_normal_disable_focused" />
<item android:drawable="@drawable/btn_default_normal_disable" />
</selector>
and my MainActivity.java is this
package com.provabottone;
import android.os.Bundle;
import android.widget.Button;
import android.app.Activity;
public class MainActivity extends Activity {
private Button mOne;
private Button mTwo;
private Button mThree;
private Button mFour;
private Button mFive;
private Button mSix;
private Button mSeven;
private Button mEight;
private Button mNine;
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
          mOne = (Button) findViewById(R.id.one);
          mTwo = (Button) findViewById(R.id.two);
          mThree  = (Button) findViewById(R.id.three);
          mFour = (Button) findViewById(R.id.four);
          mFive = (Button) findViewById(R.id.five);
          mSix = (Button) findViewById(R.id.six);
          mSeven = (Button) findViewById(R.id.seven);
          mEight = (Button) findViewById(R.id.eight);
          mNine = (Button) findViewById(R.id.nine);
           mOne.setText("1");
           mTwo.setText("2");
           mThree.setText("3");
           mFour.setText("4");
           mFive.setText("5");
           mSix.setText("6");
           mSeven.setText("7");
           mEight.setText("8");
           mNine.setText("9");
          mOne.setBackgroundResource(R.drawable.bottone_premuto);
          mTwo.setBackgroundResource(R.drawable.bottone_premuto);
          mThree.setBackgroundResource(R.drawable.bottone_premuto);
              mFour.setBackgroundResource(R.drawable.bottone_premuto);
          mFive.setBackgroundResource(R.drawable.bottone_premuto);
          mSix.setBackgroundResource(R.drawable.bottone_premuto);
          mSeven.setBackgroundResource(R.drawable.bottone_premuto);
          mEight.setBackgroundResource(R.drawable.bottone_premuto);
          mNine.setBackgroundResource(R.drawable.bottone_premuto);
}
}
now what i want is to change the color of the button pressed definite by btn_default_pressed_holo_dark when pressed,what code i need to add in my MainActivity.java? thanks in advance and sorry for long post. Hi Nicola
