ScrollingToolBar

MainActivity.java

package com.scrolltoolbar;

import android.support.v7.app.ActionBarActivity;
import android.os.Bundle;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.support.v7.widget.Toolbar;
import android.util.Log;
import android.view.Menu;
import android.view.MenuItem;
import android.view.animation.AccelerateInterpolator;
import android.view.animation.DecelerateInterpolator;

import java.util.ArrayList;
import java.util.List;

import butterknife.ButterKnife;
import butterknife.InjectView;


public class MainActivity extends ActionBarActivity {
    @InjectView(R.id.toolbar) Toolbar mToolBar;
    @InjectView(R.id.recyclerView) RecyclerView mRecyclerview;
    private int scrolledDistance = 0;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        ButterKnife.inject(this);
        setSupportActionBar(mToolBar);
        mRecyclerview.setLayoutManager(new LinearLayoutManager(this));
        RecyclerAdapter recyclerAdapter = new RecyclerAdapter(createItemList());
        mRecyclerview.setAdapter(recyclerAdapter);
        mRecyclerview.setOnScrollListener(new RecyclerView.OnScrollListener() {
            @Override
            public void onScrollStateChanged(RecyclerView recyclerView, int newState) {
                super.onScrollStateChanged(recyclerView, newState);
                if(newState == RecyclerView.SCROLL_STATE_IDLE){
                    if(scrolledDistance < -mToolBar.getHeight()/2){
                        mToolBar.animate().translationY(-mToolBar.getHeight()).setInterpolator(new DecelerateInterpolator()).start();
                        scrolledDistance = -mToolBar.getHeight();
                    }else{
                        mToolBar.animate().translationY(0).setInterpolator(new AccelerateInterpolator()).start();
                        scrolledDistance = 0;
                    }
                }
            }

            @Override
            public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
                super.onScrolled(recyclerView, dx, dy);
                scrolledDistance -= dy;
                if(dy > 0 ) {
                    checkHeight();
                    mToolBar.setTranslationY(scrolledDistance);
                }else if(dy < 0  ){
                    checkHeight();
                    mToolBar.setTranslationY(scrolledDistance);
                }
            }

        });

    }

    private void checkHeight() {
        if(scrolledDistance > 0) {
            scrolledDistance = 0;
        } else if(scrolledDistance <= -mToolBar.getHeight()) {
            scrolledDistance = -mToolBar.getHeight();
        }
    }

    private List<String> createItemList() {
        List<String> itemList = new ArrayList<>();
        for(int i=0;i<2000;i++) {
            itemList.add("Item "+i);
        }
        return itemList;
    }

}