ViewSwitcher使用例子

android.widget.ViewSwitcher是ViewAnimator的子类，用于在两个View之间切换，但每次只能显示一个View。

ViewSwitcher的addView函数的代码如下：

    /**
     * {@inheritDoc}
     *
     * @throws IllegalStateException if this switcher already contains two children
     */
    @Override
    public void addView(View child, int index, ViewGroup.LayoutParams params) {
        if (getChildCount() >= 2) {
            throw new IllegalStateException("Can't add more than 2 views to a ViewSwitcher");
        }
        super.addView(child, index, params);
    }

   

可以看出，若View的数量超过两个，会抛出异常： java.lang.IllegalStateException，打印 "Can't add more than 2 views to a ViewSwitcher" 。你可以使用ViewSwitcher的factory创建View或添加自己创建的View。

下面用一个例子介绍一下ViewSwitcher的用法。

布局文件：activity_main.xml

<?xml version="1.0" encoding="utf-8"?>

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
              xmlns:tools="http://schemas.android.com/tools"
              android:layout_width="match_parent"
              android:layout_height="match_parent"
              android:orientation="vertical"
              tools:context=".MainActivity" >


    <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:orientation="horizontal" >

        <Button
                android:id="@+id/prev"
                android:layout_width="0dp"
                android:layout_height="wrap_content"
                android:layout_weight="1"
                android:text="previous" />

        <Button
                android:id="@+id/next"
                android:layout_width="0dp"
                android:layout_height="wrap_content"
                android:layout_weight="1"
                android:text="next" />
    </LinearLayout>

    <ViewSwitcher
            android:id="@+id/viewswitcher"
            android:layout_width="match_parent"
            android:layout_height="wrap_content" >

        <ImageView
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:src="@drawable/ic_launcher" />

        <LinearLayout
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:gravity="center"
                android:orientation="vertical" >

            <Button
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:text="- Button 2 -" />

            <TextView
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:text="LinearLayout 2" />
        </LinearLayout>
    </ViewSwitcher>
</LinearLayout>

Activity的代码：

package com.example.AndroidTest;

import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.view.animation.Animation;
import android.view.animation.AnimationUtils;
import android.widget.Button;
import android.widget.ViewSwitcher;

public class MyActivity extends Activity {
    Button buttonPrev, buttonNext;
    ViewSwitcher viewSwitcher;

    Animation slide_in_left, slide_out_right;

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

        buttonPrev = (Button) findViewById(R.id.prev);
        buttonNext = (Button) findViewById(R.id.next);
        viewSwitcher = (ViewSwitcher) findViewById(R.id.viewswitcher);

        slide_in_left = AnimationUtils.loadAnimation(this,
                android.R.anim.slide_in_left);
        slide_out_right = AnimationUtils.loadAnimation(this,
                android.R.anim.slide_out_right);

        viewSwitcher.setInAnimation(slide_in_left);
        viewSwitcher.setOutAnimation(slide_out_right);

        buttonPrev.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View arg0) {
                viewSwitcher.showPrevious();
            }
        });

        buttonNext.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View arg0) {
                viewSwitcher.showNext();
            }
        });
        ;
    }
}

实现效果图：

使用ViewSwitcher的setFactory设置切换的View，分为两步。

第一步：获得ViewSwithcer的实例

switcher = (ViewSwitcher) findViewById(R.id.viewSwitcher);  

第二部：实现接口ViewFactory

  switcher.setFactory(new ViewFactory()
         {
             @Override
             public View makeView()
             {
                 return inflater.inflate(R.layout.slidelistview, null);
             }
         });