安卓開發筆記（二十五）：ViewPager的使用

• 首先我們來看看運行之後的效果：
  
  

然後我們也不多說廢話了，下麵是這個項目所需要的全部代碼，很多博主寫這個都不把代碼寫完，因此筆者自己也琢磨了一會兒才把這個弄出來，感覺很煩，但我肯定會把代碼寫全的。我這裡一共引入了三個界面，三個佈局的xml我都會寫的。

1.MainActivity.java

import android.support.v4.view.ViewPager;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;

import java.util.ArrayList;

public class MainActivity extends AppCompatActivity {
    private ViewPager vpager_one;
    private ArrayList<View> aList;
    private MyPagerAdapter mAdapter;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        vpager_one = (ViewPager) findViewById(R.id.vpager_one);

        aList = new ArrayList<View>();
        LayoutInflater li = getLayoutInflater();
        aList.add(li.inflate(R.layout.view_one,null,false));
        aList.add(li.inflate(R.layout.view_two,null,false));
        aList.add(li.inflate(R.layout.view_three,null,false));
        mAdapter = new MyPagerAdapter(aList);
        vpager_one.setAdapter(mAdapter);
    }
}

2.MypagerAdapter.java

這個是ViewPager的適配器，和listview所需要的適配器差不多,是我們創建的新類。

import android.support.v4.view.PagerAdapter;
import android.view.View;
import android.view.ViewGroup;

import java.util.ArrayList;

public class MyPagerAdapter extends PagerAdapter {

    private ArrayList<View> viewLists;

    public MyPagerAdapter() {
    }

    public MyPagerAdapter(ArrayList<View> viewLists) {
        super();
        this.viewLists = viewLists;
    }

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

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

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

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

3.activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.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">


    <android.support.v4.view.ViewPager
        android:id="@+id/vpager_one"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center" />

</android.support.constraint.ConstraintLayout>

4.view_one

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="#FFBA55"
    android:gravity="center"
    android:orientation="vertical">

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="第一個Page"
        android:textColor="#000000"
        android:textSize="18sp"
        android:textStyle="bold" />

</LinearLayout>

5.view_two

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="#FFBA55"
    android:gravity="center"
    android:orientation="vertical">

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="第二個Page"
        android:textColor="#000000"
        android:textSize="18sp"
        android:textStyle="bold" />

</LinearLayout>

6.view_three

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="#FFBA55"
    android:gravity="center"
    android:orientation="vertical">

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="第三個Page"
        android:textColor="#000000"
        android:textSize="18sp"
        android:textStyle="bold" />
</LinearLayout>

得解，就這麼簡單。我真是不知道其他博主為啥不把代碼寫全，尤其是每個viewpager的佈局，連說都不說下有三個佈局，真實讓人頭大。