how i can link the CircularPageIndicator with next and back buttons

Question

import android.annotation.SuppressLint;
import android.os.Bundle;
import android.support.v4.app.FragmentActivity;
import android.support.v4.view.ViewPager;
import android.view.View;
import android.view.Window;
import android.widget.Button;
import android.widget.TextView;

@SuppressLint("NewApi")
public class Main2Activity extends FragmentActivity
{

private ViewPager viewPager;
private TabsPagerAdapter mAdapter;
TextView skip;
Button bt1,bt2,bt3,bt4;
Button back;
Button next;

@SuppressLint("NewApi")
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
this.requestWindowFeature(Window.FEATURE_NO_TITLE);
setContentView(R.layout.activity_main2);

back=(Button) findViewById(R.id.back);
next=(Button) findViewById(R.id.next);

bt1=(Button) findViewById(R.id.btn1);
bt2=(Button) findViewById(R.id.btn2);
bt3=(Button) findViewById(R.id.btn3);

viewPager = (ViewPager) findViewById(R.id.pager);

mAdapter = new TabsPagerAdapter(getSupportFragmentManager());

viewPager.setAdapter(mAdapter);

viewPager.addOnPageChangeListener(new ViewPager.OnPageChangeListener() {

@Override
public void onPageSelected(int position) {

btnAction(position);

}

@Override
public void onPageScrolled(int arg0, float arg1, int arg2) {

}

@Override
public void onPageScrollStateChanged(int arg0) {

}
});
}
private void btnAction(int action){
switch(action){
case 0:
setButton(bt2,4,15,R.drawable.circle2);
setButton(bt1,4,15,R.drawable.circle);
setButton(bt3,4,15,R.drawable.circle);

break;

case 1: setButton(bt1,4,15,R.drawable.circle2);
setBut

Answer 1

1. You can use android lib and set pager indicator to view pager.
com.viewpagerindicator.CirclePageIndicator;

indicator.setViewPager(mPager);

2. OnButtonClick()
mPager.setCurrentItem(1, true);