ViewSwitcher使用例子

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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);
}
});

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