bottom_sheet_behavior.java

LinearLayout bottomSheet = findViewById(R.id.bottom_sheet_behavior_id);
BottomSheetBehavior bottomSheetBehavior = BottomSheetBehavior.from(bottomSheet);

// ..
// here you could find all the UI views inside your bottom sheet and initialize them
// ..

// ..
// setting the bottom sheet callback for interacting with state changes and sliding
bottomSheetBehavior.setBottomSheetCallback(new BottomSheetBehavior.BottomSheetCallback() {
  @Override
  public void onStateChanged(View view, int i) {
    // do something when state changes
  }

  @Override
  public void onSlide(View view, float v) {
    // do something when slide happens
  }
});

// ..
// set the bottom sheet callback state to hidden when you just start your app
bottomSheetBehavior.setState(BottomSheetBehavior.STATE_HIDDEN);