Android实现滑动屏幕切换图片

<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"  xmlns:app="http://schemas.android.com/apk/res-auto"  xmlns:tools="http://schemas.android.com/tools"  android:layout_width="match_parent"  android:layout_height="match_parent"  tools:context="com.example.administrator.hand_gliding.MainActivity">   <ImageView    android:layout_width="match_parent"    android:layout_height="match_parent"    android:id="@+id/imageView"    android:src="@drawable/a1"/> </LinearLayout>

package com.example.administrator.hand_gliding; import android.support.v7.app.AppCompatActivity;import android.os.Bundle;import android.view.GestureDetector;import android.view.MotionEvent;import android.widget.ImageView; public class MainActivity extends AppCompatActivity {   //定义图片  private int[] resId = new int[]{      R.drawable.a1,R.drawable.a2,R.drawable.a3,R.drawable.a4,      R.drawable.a5,R.drawable.a6,R.drawable.a7  };  //图片下标序号  private int count = 0;  //定义手势监听对象  private GestureDetector gestureDetector;  //定义ImageView对象  private ImageView iv;   @Override  protected void onCreate(Bundle savedInstanceState) {    super.onCreate(savedInstanceState);    setContentView(R.layout.activity_main);        iv = (ImageView)findViewById(R.id.imageView);        //获取ImageView控件id    gestureDetector = new GestureDetector(onGestureListener);  //设置手势监听由onGestureListener处理   }   //当Activity被触摸时回调  public boolean onTouchEvent(MotionEvent event){    return gestureDetector.onTouchEvent(event);  }  //自定义GestureDetector的手势识别监听器  private GestureDetector.OnGestureListener onGestureListener      = new GestureDetector.SimpleOnGestureListener(){    //当识别的手势是滑动手势时回调onFinger方法    public boolean onFling(MotionEvent e1,MotionEvent e2,float velocityX,float velocityY){      //得到手触碰位置的起始点和结束点坐标 x , y ，并进行计算      float x = e2.getX()-e1.getX();      float y = e2.getY()-e1.getY();      //通过计算判断是向左还是向右滑动      if(x > 0){        count++;        count%=(resId.length-1);    //想显示多少图片，就把定义图片的数组长度-1      }else if(x < 0){        count--;        count=(count+(resId.length-1))%(resId.length-1);      }       iv.setImageResource(resId[count]); //切换imageView的图片      return true;    }  };}