ُsetOnTabSelectedListener

toolbar=(Toolbar)findViewById(R.id.toolbar);
setSupportActionBar(toolbar);

final Fragment fragment = new Fragment();
getSupportFragmentManager()
.beginTransaction()
.replace(R.id.frame,fragment)
.commit();
final String[] colors = {"#96CC7A", "#EA705D", "#66BBCC","#EA755D"};
AHBottomNavigation bottomNavigation = (AHBottomNavigation) findViewById(R.id.bottom_navigation);
AHBottomNavigationItem item1 = new AHBottomNavigationItem("خانه",
R.drawable.four,
Color.parseColor(colors[0]));
AHBottomNavigationItem item2 = new AHBottomNavigationItem("گالری",
R.drawable.one,
Color.parseColor(colors[1]));
AHBottomNavigationItem item3 = new AHBottomNavigationItem("فیلم",
R.drawable.two,
Color.parseColor(colors[2]));
AHBottomNavigationItem item4 = new AHBottomNavigationItem("کتابخانه",
R.drawable.three,
Color.parseColor(colors[3]));
bottomNavigation.setAccentColor(Color.parseColor("#F63D2B"));
bottomNavigation.setInactiveColor(Color.parseColor("#747474"));
bottomNavigation.setDefaultBackgroundColor(Color.parseColor("#FEFEFE"));
//
Bundle bundle = new Bundle();
bundle.putInt("color", Color.parseColor(colors[0]));
fragment.setArguments(bundle);
// Enables Reveal effect
bottomNavigation.setColored(true);

bottomNavigation.setCurrentItem(0);
//add item to the navigation bar
bottomNavigation.addItem(item1);
bottomNavigation.addItem(item2);
bottomNavigation.addItem(item3);
bottomNavigation.addItem(item4);
// add listener
bottomNavigation.setOnTabSelectedListener(new AHBottomNavigation.OnTabSelectedListener() {
@Override
public void onTabSelected(int position, boolean wasSelected) {
Fragment fragment = null;

FragmentManager fragmentManager=getSupportFragmentManager();

switch (position ){
case 0:
fragment =new FragmentLearmen();
break;
case 1:
fragment= new GalleryFragment();
break;

}

fragmentManager.beginTransaction().replace(R.id.frame,fragment).commit();

}
});
}
}