How to open navigation drawer on button click in main fragment?

if you need open the slide:

mDrawerLayout.openDrawer(Gravity.LEFT); //Edit Gravity.START need API 14

if you need close the slide

mDrawerLayout.closeDrawer(Gravity.LEFT); //Edit Gravity.START need API 14

EXAMPLE

my mDrawerLayout is instanced here:

mDrawerLayout = (DrawerLayout)findViewById(R.id.my_drawer_layout);

my slide state:

mSlideState=false;

if you need to know the slide menu state (closed, opened). Use this code:

mDrawerLayout.setDrawerListener(new ActionBarDrawerToggle(this, 
    mDrawerLayout, 
    R.drawable.ic_menu_slide,
    0,
    0){
@Override
public void onDrawerClosed(View drawerView) {                       
    super.onDrawerClosed(drawerView);
    mSlideState=false;//is Closed
}
@Override
public void onDrawerOpened(View drawerView) {                       
    super.onDrawerOpened(drawerView);
    mSlideState=true;//is Opened
}});

finally. You can use your click event like this:

public void clickEventSlide(){
if(mSlideState){                
    mDrawerLayout.closeDrawer(Gravity.END);
}else{              
    mDrawerLayout.openDrawer(Gravity.END);
}}

In my case, my slide menu is at the right (Gravity.END), but if you need it on the left, try with Gravity.START