Android ViewPager簡單使用-有解無憂

效果圖

功能代碼

創建一個集合，存盤ViewPager的四張圖片

//四張廣告圖片添加到集合中進行保存
        List<View>listPics=new ArrayList<>();
        //第一張
        ImageView img1=new ImageView(this);
        img1.setBackgroundResource(R.drawable.img1);
        listPics.add(img1);
        //第二張
        ImageView img2=new ImageView(this);
        img2.setBackgroundResource(R.drawable.img2);
        listPics.add(img2);
        //第三張
        ImageView img3=new ImageView(this);
        img3.setBackgroundResource(R.drawable.img3);
        listPics.add(img3);
        //第四張
        ImageView img4=new ImageView(this);
        img4.setBackgroundResource(R.drawable.img4);
        listPics.add(img4);

動態設定ViewPager右下角四個小圓點的屬性

 //動態設定四個圓點的屬性
        indicators=new ImageView[listPics.size()];
        //遍歷該陣列一個個動態加載
        for (int i=0;i<indicators.length;i++){
            indicator=new ImageView(this);
            //設定這張圖片在布局中的引數（指定寬度和高度）
            indicator.setLayoutParams(new LinearLayout.LayoutParams(40,40));
            //小圓點的間隔
            indicator.setPadding(5,5,5,5);
            //
            indicators[i]=indicator;
            if (i==0){
                indicators[i].setBackgroundResource(R.drawable.dian_f);
            }else {
                indicators[i].setBackgroundResource(R.drawable.dian_b);
            }
            group.addView(indicators[i]);
        }

設定viewPager的監聽器

  //設定viewPager的監聽器
        viewPager.setOnPageChangeListener(new ViewPager.OnPageChangeListener() {
            //當頁面翻滾
            @Override
            public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {

            }
            //當頁面被選中
            @Override
            public void onPageSelected(int position) {
                //記錄當前位置
//                index.getAndSet(position);
                for (int i=0;i<indicators.length;i++){
                    //如果陣列的當前下標就是當前位置
                    if (i==position){
                        indicators[i].setBackgroundResource(R.drawable.dian_f);
                    }else {
                        indicators[i].setBackgroundResource(R.drawable.dian_b);
                    }

                }
            }

            @Override
            public void onPageScrollStateChanged(int state) {

            }
        });

配接器

//創建一個配接器
class MyPagerAdapter extends PagerAdapter{
    private List<View>viewList;
    //將集合作為構造方法的引數傳遞進來
    public MyPagerAdapter(List<View>viewList){
        this.viewList=viewList;
    }
    @Override
    public int getCount() {
        return viewList.size();
    }

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

    //視圖的創建，創建每一頁viewpager的時候instantiateItem將會被自動呼叫
    @NonNull
    @Override
    public Object instantiateItem(@NonNull ViewGroup container, int position) {
        container.addView(viewList.get(position),0);
        return viewList.get(position);
    }
    //視圖的移除
    @Override
    public void destroyItem(@NonNull ViewGroup container, int position, @NonNull Object object) {
        container.removeView(viewList.get(position));
    }
}

自動翻頁功能（兩秒）

使用多執行緒

//使用多執行緒自動定時切換page
        new Thread(new Runnable() {
            @Override
            public void run() {
                while (true){
                    //回圈一直執行，每隔兩秒，通過Handler，發出一條訊息帶去當前ViewPager所顯示的頁的索引號
                    if (isContinue){
                        viewHandler.sendEmptyMessage(index.get());
                        whatOption();
                    }
                }

            }
        }).start();
    }
    private void whatOption(){
        index.incrementAndGet();//將當前位置值加1
        if (index.get()>indicators.length-1){
            index.getAndAdd(-4);
        }
        //設定一個執行緒每隔兩秒啟動
        try {
            Thread.sleep(2000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }

宣告一個 Handler，接收指令并更換視圖

   private Handler viewHandler=new Handler(){
      public void handleMessage(Message msg){
          super.handleMessage(msg);
          //將當前的msg.what，也就是index的值置為當前page的值
          viewPager.setCurrentItem(msg.what);
      }
    };

監聽viewPager按壓，如果按壓則停止執行緒，放開則繼續

      viewPager.setOnTouchListener(new View.OnTouchListener() {
            @Override
            public boolean onTouch(View view, MotionEvent motionEvent) {
                switch (motionEvent.getAction()){
                    //如果狀態為壓下，則停止
                    case MotionEvent.ACTION_DOWN:
                        isContinue=false;
                        break;
                    case MotionEvent.ACTION_UP:
                        isContinue=true;
                        break;
                }
                return false;
            }
        });

全部代碼

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout 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">

  <LinearLayout
      android:layout_width="match_parent"
      android:layout_height="match_parent"
      android:orientation="vertical">
      <RelativeLayout
          android:layout_width="match_parent"
          android:layout_height="wrap_content">
          <androidx.viewpager.widget.ViewPager
              android:id="@+id/vp_adv"
              android:layout_width="match_parent"
              android:layout_height="160dp">
          </androidx.viewpager.widget.ViewPager>
          <LinearLayout
              android:id="@+id/view_indicators"
              android:layout_width="match_parent"
              android:layout_height="wrap_content"
              android:layout_below="@+id/vp_adv"
              android:layout_marginTop="-25dp"
              android:gravity="right"
              android:orientation="horizontal">
          </LinearLayout>
      </RelativeLayout>
  </LinearLayout>
</androidx.constraintlayout.widget.ConstraintLayout>

MainActivity.java

package com.cdw.study6;

import androidx.annotation.NonNull;
import androidx.appcompat.app.AppCompatActivity;
import androidx.viewpager.widget.PagerAdapter;
import androidx.viewpager.widget.ViewPager;

import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.view.MotionEvent;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.LinearLayout;

import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.atomic.AtomicInteger;

public class MainActivity extends AppCompatActivity {
    private ImageView indicator;//表示圓點指示器
    private ImageView[] indicators;//保存四個圓點指示器的陣列
    private boolean isContinue=true;
    private ViewPager viewPager;
    private ViewGroup group;
    private AtomicInteger index=new AtomicInteger();
    private Handler viewHandler=new Handler(){
      public void handleMessage(Message msg){
          super.handleMessage(msg);
          //將當前的msg.what，也就是index的值置為當前page的值
          viewPager.setCurrentItem(msg.what);
      }
    };

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        initView();
    }
    private void initView(){
        viewPager=findViewById(R.id.vp_adv);
        group=findViewById(R.id.view_indicators);

        //四張廣告圖片添加到集合中進行保存
        List<View>listPics=new ArrayList<>();
        //第一張
        ImageView img1=new ImageView(this);
        img1.setBackgroundResource(R.drawable.img1);
        listPics.add(img1);
        //第二張
        ImageView img2=new ImageView(this);
        img2.setBackgroundResource(R.drawable.img2);
        listPics.add(img2);
        //第三張
        ImageView img3=new ImageView(this);
        img3.setBackgroundResource(R.drawable.img3);
        listPics.add(img3);
        //第四張
        ImageView img4=new ImageView(this);
        img4.setBackgroundResource(R.drawable.img4);
        listPics.add(img4);

        //動態設定四個圓點的屬性
        indicators=new ImageView[listPics.size()];
        //遍歷該陣列一個個動態加載
        for (int i=0;i<indicators.length;i++){
            indicator=new ImageView(this);
            //設定這張圖片在布局中的引數（指定寬度和高度）
            indicator.setLayoutParams(new LinearLayout.LayoutParams(40,40));
            //小圓點的間隔
            indicator.setPadding(5,5,5,5);
            //
            indicators[i]=indicator;
            if (i==0){
                indicators[i].setBackgroundResource(R.drawable.dian_f);
            }else {
                indicators[i].setBackgroundResource(R.drawable.dian_b);
            }
            group.addView(indicators[i]);
        }
        //設定viewPager的配接器
        viewPager.setAdapter(new MyPagerAdapter(listPics));
        //設定viewPager的監聽器
        viewPager.setOnPageChangeListener(new ViewPager.OnPageChangeListener() {
            //當頁面翻滾
            @Override
            public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {

            }
            //當頁面被選中
            @Override
            public void onPageSelected(int position) {
                //記錄當前位置
//                index.getAndSet(position);
                for (int i=0;i<indicators.length;i++){
                    //如果陣列的當前下標就是當前位置
                    if (i==position){
                        indicators[i].setBackgroundResource(R.drawable.dian_f);
                    }else {
                        indicators[i].setBackgroundResource(R.drawable.dian_b);
                    }

                }
            }

            @Override
            public void onPageScrollStateChanged(int state) {

            }
        });

        viewPager.setOnTouchListener(new View.OnTouchListener() {
            @Override
            public boolean onTouch(View view, MotionEvent motionEvent) {
                switch (motionEvent.getAction()){
                    //如果狀態為壓下，則停止
                    case MotionEvent.ACTION_DOWN:
                        isContinue=false;
                        break;
                    case MotionEvent.ACTION_UP:
                        isContinue=true;
                        break;
                }
                return false;
            }
        });

        //使用多執行緒自動定時切換page
        new Thread(new Runnable() {
            @Override
            public void run() {
                while (true){
                    //回圈一直執行，每隔兩秒，通過Handler，發出一條訊息帶去當前ViewPager所顯示的頁的索引號
                    if (isContinue){
                        viewHandler.sendEmptyMessage(index.get());
                        whatOption();
                    }
                }

            }
        }).start();
    }
    private void whatOption(){
        index.incrementAndGet();//將當前位置值加1
        if (index.get()>indicators.length-1){
            index.getAndAdd(-4);
        }
        //設定一個執行緒每隔兩秒啟動
        try {
            Thread.sleep(2000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }

}
//創建一個配接器
class MyPagerAdapter extends PagerAdapter{
    private List<View>viewList;
    //將集合作為構造方法的引數傳遞進來
    public MyPagerAdapter(List<View>viewList){
        this.viewList=viewList;
    }
    @Override
    public int getCount() {
        return viewList.size();
    }

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

    //視圖的創建，創建每一頁viewpager的時候instantiateItem將會被自動呼叫
    @NonNull
    @Override
    public Object instantiateItem(@NonNull ViewGroup container, int position) {
        container.addView(viewList.get(position),0);
        return viewList.get(position);
    }
    //視圖的移除
    @Override
    public void destroyItem(@NonNull ViewGroup container, int position, @NonNull Object object) {
        container.removeView(viewList.get(position));
    }
}

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