The up / down monitoring of listview hides the instance of the top option bar

Listview's up and down monitoring to hide and display the special effects in the top option bar. This special effect is available in the resource list of JD Tongcheng and other apps

Two key points:

① Setontouchlistener listening method of listview

When the sliding y position minus the pressed y position is greater than the minimum sliding distance, it is sliding downward

Conversely, when the pressed y position minus the sliding y position is greater than the minimum sliding distance, it is sliding upward

② Displacement animation

As long as these two points need to be noted, directly on the code, the comments are very clear.

package com.example.android_topbar_gone;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import android.animation.Animator;
import android.animation.ObjectAnimator;
import android.app.Activity;
import android.os.Bundle;
import android.view.MotionEvent;
import android.view.View;
import android.view.View.OnTouchListener;
import android.view.ViewConfiguration;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.ListView;
import android.widget.RelativeLayout;
import android.widget.SimpleAdapter;
import android.widget.Toast;
public class MainActivity extends Activity {
  private RelativeLayout top_rl;
  private ListView listview;
  private List<Map<String,Object>>list = new ArrayList<Map<String,Object>>();
  private int mTouchShop;//最小滑动距离
  protected float mFirstY;//触摸下去的位置
  protected float mCurrentY;//滑动时Y的位置
  protected int direction;//判断是否上滑或者下滑的标志
  protected boolean mShow;//判断是否执行了上滑动画
  private Animator mAnimator;//动画属性
  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    //初始化id
    setViews();
    //加载listview
    setListView();
  }
  /**
   * 初始化id
   */
  private void setViews() {
    top_rl = (RelativeLayout) findViewById(R.id.rl_ttt);
    listview = (ListView) findViewById(R.id.listview);
  }
  /**
   * 加载listview
   */
  private void setListView() {
    View header = View.inflate(this,R.layout.headview,null);//自定义一个头布局和顶部执行动画的布局等高就行
    listview.addHeaderView(header);//加载头布局
    //获得一个最小滑动距离
    mTouchShop = ViewConfiguration.get(this).getScaledTouchSlop();//系统级别的一个属性,判断用户的最小滑动距离的,可查看源码为16
    //给集合添加数据
    for (int i = 0; i < 40; i++) {
      Map<String,Object>map = new HashMap<String,Object>();
      map.put("str","第"+i+"个item");
      list.add(map);
    }
    String a[] = {"str"};
    int b[] = {R.id.tv01};
    //simpleadapter加载集合数据
    SimpleAdapter adapter = new SimpleAdapter(this,list,R.layout.item,a,b);
    listview.setAdapter(adapter);
    listview.setOnItemClickListener(new OnItemClickListener() {//listview的点击方法
      @Override
      public void onItemClick(AdapterView<?> arg0,View arg1,int arg2,long arg3) {
        Toast.makeText(MainActivity.this,list.get(arg2-1).get("str")+"",0).show();//-1是因为加载的头布局
      }
    });
    listview.setOnTouchListener(new OnTouchListener() {//listview的触摸事件
      @Override
      public boolean onTouch(View v,MotionEvent event) {
        switch (event.getAction()) {
        case MotionEvent.ACTION_DOWN:
          mFirstY = event.getY();//按下时获取位置
          break;
        case MotionEvent.ACTION_MOVE:
          mCurrentY = event.getY();//得到滑动的位置
          if(mCurrentY - mFirstY > mTouchShop){//滑动的位置减去按下的位置大于最小滑动距离 则表示向下滑动
            direction = 0;//down
          }else if(mFirstY - mCurrentY > mTouchShop){//反之向上滑动
            direction = 1;//up
          }
          if(direction == 1){//判断如果是向上滑动 则执行向上滑动的动画
            if(mShow){//判断动画是否执行了 执行了则改变状态
              //执行往上滑动的动画
              tolbarAnim(1);
              mShow = !mShow;
            }
          }else if(direction == 0){//判断如果是向下滑动 则执行向下滑动的动画
            if(!mShow){//判断动画是否执行了 执行了则改变状态
              //执行往下滑动的动画
              tolbarAnim(0);
              mShow = !mShow;
            }
          }
          break;
        case MotionEvent.ACTION_UP:
          break;
        }
        return false;
      }
    });
  }

  private void tolbarAnim(int flag){
    if(mAnimator != null && mAnimator.isRunning()){//判断动画存在 如果启动了,则先关闭
      mAnimator.cancel();
    }
    if(flag == 0){
      mAnimator = ObjectAnimator.ofFloat(top_rl,"translationY",top_rl.getTranslationY(),0);//从当前位置位移到0位置
    }else{
      mAnimator = ObjectAnimator.ofFloat(top_rl,-top_rl.getHeight());//从当前位置移动到布局负高度的wiz
    }
    mAnimator.start();//执行动画
  }

}