android 圖片瀏覽器滑動切換圖片

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="horizontal" >
    <!-- 定義ImageView控件 -->
    <ImageView
        android:id="@+id/Iv"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        android:src="@drawable/k1" />
</RelativeLayout>

package com.example.yanlei.yl;

import android.graphics.Color;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;

import android.view.Menu;
import android.view.MenuItem;
import android.widget.TextView;
import android.text.Html;
import android.text.Html.ImageGetter;

import java.util.regex.Matcher;
import java.util.regex.Pattern;

import android.text.Editable;
import android.text.TextWatcher;
import android.widget.EditText;
import android.widget.Button;


import android.app.Activity;
import android.content.Intent;


import android.view.GestureDetector;
import android.view.MotionEvent;
import android.widget.ImageView;


public class MainActivity extends AppCompatActivity {
    // 定義保存ImageView的對象
    private ImageView Iv;
    //定義手勢檢測器對象
    private GestureDetector gestureDetector;
    //定義圖片的資源數組
    private int[] ResId = new int[]{
            R.drawable.k1,
            R.drawable.k2,
            R.drawable.k3
    };
    //定義當前顯示的圖片的下標
    private int count = 0;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_main);
        findView();
        setListener();
    }

    private void setListener() {
        //設置手勢監聽器的處理效果由onGestureListener來處理
        gestureDetector = new GestureDetector(MainActivity.this,
                onGestureListener);
    }

    @Override
    public boolean onTouchEvent(MotionEvent event) {
        //當前Activity被觸摸時回調
        return gestureDetector.onTouchEvent(event);
    }

    private void findView() {
        //得到當前頁面的imageview控件
        Iv = (ImageView) findViewById(R.id.Iv);
    }
    //定義了GestureDetector的手勢識別監聽器
    private GestureDetector.OnGestureListener onGestureListener
            = new GestureDetector.SimpleOnGestureListener() {
        //當識別的收拾是滑動手勢時回調onFinger方法
        @Override
        public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX,
                               float velocityY) {
            //得到滑動手勢的其實和結束點的x，y坐標，並進行計算
            float x = e2.getX() - e1.getX();
            float y = e2.getY() - e1.getY();

            //通過計算結果判斷用戶是向左滑動或者向右滑動
            if (x > 0) {
                count++;
                count %= 3;
            } else if (x < 0) {
                count--;
                count = (count + 3) % 3;
            }
            //切換imageview的圖片
            changeImg();
            return true;
        }
    };

    public void changeImg() {
        //設置當前位置的圖片資源
        Iv.setImageResource(ResId[count]);
    }



}