How to Change Background Colour of Action Bar in Android?

package com.example.change_background_action_bar;
 
import android.R.drawable;
import android.annotation.SuppressLint;
import android.app.ActionBar;
import android.app.Activity;
import android.graphics.drawable.Drawable;
import android.os.Bundle;
import android.view.Menu;
import android.view.View;
import android.widget.Button;
 
@SuppressLint("NewApi")
public class MainActivity extends Activity {
 
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Button change = (Button)findViewById(R.id.button1);
        change.setOnClickListener(new View.OnClickListener() {
 
            @Override
            public void onClick(View v) {
                // TODO Auto-generated method stub
                ActionBar actionBar = getActionBar();
                Drawable dr;
                dr = Drawable.createFromPath("@drawable/bar");
                actionBar.setBackgroundDrawable(dr);
 
            }
        });
    }
 
    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }
 
}