Android ViewPager图片切换的简单案例

编程语言 12/13 阅读 683 views次 人气 0
摘要:

1)ViewPager类直接继承了ViewGroup类,所有它是一个容器类,可以在其中添加其他的view类。

2)ViewPager类需要一个PagerAdapter适配器类给它提供数据。

向右滑动切换图片

MainActivity
package com.shaoxin.myviewpager;

import android.os.Bundle;
import android.support.v4.view.PagerAdapter;
import android.support.v4.view.ViewPager;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;

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

public class MainActivity extends AppCompatActivity {
    private ViewPager viewpager;
    private List<ImageView> imageViewList;
    private int[] imgId = {R.drawable.a, R.drawable.b, R.drawable.c, R.drawable.d};

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        viewpager = (ViewPager) findViewById(R.id.viewpager);
        imageViewList = new ArrayList<>();
        for (int i = 0; i < imgId.length; i++) {
            ImageView imgview = new ImageView(this);
            imgview.setBackgroundResource(imgId[i]);
            imageViewList.add(imgview);
        }
        MyAdapter adapter = new MyAdapter();
        viewpager.setAdapter(adapter);
    }

    private class MyAdapter extends PagerAdapter {

        @Override
        public int getCount() {
            return imageViewList.size();
        }

        @Override
        public boolean isViewFromObject(View view, Object object) {
            return view == object;
        }

        @Override
        public Object instantiateItem(ViewGroup container, int position) {
            container.addView(imageViewList.get(position));
            return imageViewList.get(position);
        }

        @Override
        public void destroyItem(ViewGroup container, int position, Object object) {
            container.removeView(imageViewList.get(position));
        }
    }
}

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/activity_main"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context="com.shaoxin.myviewpager.MainActivity">

    <android.support.v4.view.ViewPager
        android:id="@+id/viewpager"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />
</RelativeLayout>

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