今日所学—Android中ViewPager的使用

 

 

 

 代码部分：

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">

    <androidx.viewpager.widget.ViewPager
        android:id="@+id/viewpager"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        tools:layout_editor_absoluteX="1dp"
        tools:layout_editor_absoluteY="1dp" />

</androidx.constraintlayout.widget.ConstraintLayout>

a1.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical" android:layout_width="match_parent"
    android:layout_height="match_parent">

    <TextView
        android:id="@+id/textView"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="第一个界面" />
</LinearLayout>

a2.xml  a3.xml  和  a1 相同

MainActivity.java

package com.example.viewpagertest;

import androidx.appcompat.app.AppCompatActivity;
import androidx.viewpager.widget.ViewPager;

import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;

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

public class MainActivity extends AppCompatActivity {
    private ViewPager viewPager;
    private List<View> views;
    private MyNewAdapter myNewAdapter;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        viewPager = findViewById(R.id.viewpager);
        views = new ArrayList<View>();
        LayoutInflater layoutInflater = LayoutInflater.from(getApplicationContext());

        View view1 = layoutInflater.inflate(R.layout.a1,null);
        View view2 = layoutInflater.inflate(R.layout.a2,null);
        View view3 = layoutInflater.inflate(R.layout.a3,null);
        views.add(view1);
        views.add(view2);
        views.add(view3);

        myNewAdapter = new MyNewAdapter(views);
        viewPager.setAdapter(myNewAdapter);

    }
}

MyNewAdapter.java

package com.example.viewpagertest;

import android.view.View;
import android.view.ViewGroup;

import androidx.annotation.NonNull;
import androidx.viewpager.widget.PagerAdapter;
import androidx.viewpager.widget.ViewPager;

import java.util.List;

public class MyNewAdapter extends PagerAdapter {
    List<View> views;

    public MyNewAdapter(List<View> views) {
        this.views = views;
    }

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

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

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

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

效果图：

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