Handler+Viewpager无限轮播

最新推荐文章于 2020-02-16 19:29:56 发布

原创最新推荐文章于 2020-02-16 19:29:56 发布 · 226 阅读

CC 4.0 BY-SA版权

本文详细介绍如何在Android应用中使用ViewPager与RadioGroup组件进行联动显示。通过自定义适配器，实现图片轮播功能，并利用RadioGroup作为指示器，展示当前ViewPager页面位置。文章还提供了完整的代码示例，包括XML布局文件和Java代码。

XML

<?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=".MainActivity"
    android:orientation="vertical"
    >
    <android.support.v4.view.ViewPager
        android:id="@+id/viewpager"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:layout_weight="1"
        ></android.support.v4.view.ViewPager>
    <RadioGroup
        android:id="@+id/radiogroup"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:gravity="center"
        android:orientation="horizontal"
        ></RadioGroup>
</LinearLayout>

MathActivity.this

package com.example.kanghuwei.viewpager;

import android.os.Handler;
import android.os.Message;
import android.support.v4.view.ViewPager;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.widget.ImageView;
import android.widget.RadioButton;
import android.widget.RadioGroup;

import java.util.ArrayList;

public class MainActivity extends AppCompatActivity {
    private ViewPager viewpager;
    private ArrayList<ImageView> list = new ArrayList<>();
    private MyPageradapter adapter;
    private RadioGroup radioGroup;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        viewpager = findViewById(R.id.viewpager);

        int arr[] = {R.drawable.a1, R.drawable.a2, R.drawable.a3, R.drawable.a4, R.drawable.a5, R.drawable.a6};
        for (int i = 0; i < arr.length; i++) {
            ImageView imageView = new ImageView(MainActivity.this);
            imageView.setImageResource(arr[i]);
            list.add(imageView);
        }
        adapter = new MyPageradapter(list);
        viewpager.setAdapter(adapter);

        radioGroup = findViewById(R.id.radiogroup);
        for (int i = 0; i < arr.length; i++) {
            RadioButton button = new RadioButton(MainActivity.this);
            radioGroup.addView(button);
        }
        radioGroup.check(radioGroup.getChildAt(0).getId());

        viewpager.setOnPageChangeListener(new ViewPager.OnPageChangeListener() {
            @Override
            public void onPageScrolled(int i, float v, int i1) {

            }

            @Override
            public void onPageSelected(int i) {
                i = i % list.size();
                radioGroup.check(radioGroup.getChildAt(i).getId());
            }

            @Override
            public void onPageScrollStateChanged(int i) {

            }
        });
        handler.sendEmptyMessageDelayed(0, 3000);
    }

    final Handler handler = new Handler() {
        @Override
        public void handleMessage(Message msg) {
            super.handleMessage(msg);
            switch (msg.what) {
                case 0:
                    int currentItem = viewpager.getCurrentItem();
                    currentItem += 1;
                    viewpager.setCurrentItem(currentItem);
                    handler.sendEmptyMessageDelayed(0, 3000);
                    break;
            }
        }
    };
}

Viewpager适配器

package com.example.kanghuwei.viewpager;

import android.content.Context;
import android.support.annotation.NonNull;
import android.support.v4.view.PagerAdapter;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;

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

class MyPageradapter extends PagerAdapter {
    private ArrayList<ImageView> list;

    public MyPageradapter(ArrayList<ImageView> list) {
        super();
        this.list = list;
    }

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

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

    @NonNull
    @Override
    public Object instantiateItem(@NonNull ViewGroup container, int position) {
        ImageView imageView = list.get(position);
        container.addView(imageView);
        return imageView;
    }

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