所有android应用都将具有切换不同视图的功能，以说明/推广其网站或产品。通过显示不同的视图来直观表示产品，将轻松打动客户。在本文中，让我们看看如何将“ ViewSwitcher”引入Android。 ViewSwitcher是ViewAnimator的子类，用于在视图之间切换，从而为客户带来不同的视图。它是过渡小部件的一个元素，可帮助我们在视图上添加过渡。我们可以用它来动画屏幕上的视图。 ViewSwitcher甚至在两个不同的视图(即TextView，ImageView或任何布局)之间也可以平滑切换，并且由于此功能，可以通过在需要时交替显示TextView，Imageview来打动客户。在我们的示例中，让我们看一下ImageView本身。
Important Note: ViewSwitcher can only have two child views and that only one is shown at a time. If you have more than two child views in ViewSwitcher, java.lang.IllegalStateException of “Can’t add more than 2 views to a ViewSwitcher” error will come.
ViewSwitcher初始化
Java
// We can intialize ViewSwitcher in the below way , where
// simpleViewSwitcher1
// is the id of ViewSwitcher in xml file. Usually xml file
// name will be
// activity_main but we can have meaningful name.
// let our xml file name be activity_viewswitcher
ViewSwitcher simpleViewSwitcher1 = (ViewSwitcher)findViewById(R.id.simpleViewSwitcher1);XML
Java
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;
import androidx.appcompat.app.AppCompatActivity;
public class MainActivity extends AppCompatActivity {
private ViewSwitcher simpleViewSwitcher;
Button btnNext, btnPrev;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// get The references of Button and ViewSwitcher
btnNext = (Button) findViewById(R.id.buttonNext);
btnPrev = (Button) findViewById(R.id.buttonPrevious);
// get the reference of ViewSwitcher
simpleViewSwitcher = (ViewSwitcher) findViewById(R.id.simpleViewSwitcher);
// Declare in and out animations and load them using AnimationUtils class
Animation in = AnimationUtils.loadAnimation(this, android.R.anim.slide_in_left);
Animation out = AnimationUtils.loadAnimation(this, android.R.anim.slide_out_right);
// set the animation type to ViewSwitcher
simpleViewSwitcher.setInAnimation(in);
simpleViewSwitcher.setOutAnimation(out);
// ClickListener for NEXT button
// When clicked on Button ViewSwitcher will switch between views
// The current view will go out and next view will come in with specified animation
btnNext.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
// show the next view of ViewSwitcher
simpleViewSwitcher.showNext();
}
});
btnPrev.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
// show the previous view of ViewSwitcher
simpleViewSwitcher.showPrevious();
}
});
}
}让我们看看ViewSwitcher的重要方法，其功能以及其代码实现
重要方法
通用方法及其说明：
|
General Methods |
Description |
|---|---|
| getNextView() |
In order to return to the next view to be displayed in ViewSwitcher, the getNextView() method is used and it returns the view id of the next view to be displayed. |
| reset() |
There may be a requirement to reset the ViewSwitcher on a click event and hence it behaves like the first-time animation has not yet played. reset() method is used for that. |
| showNext() |
ViewSwitcher can have only 2 views. Only one view is shown at a time. To show the next view, the required method is showNext() |
| showPrevious() |
ViewSwitcher can have only 2 views. Only one view is shown at a time. To show the previous view, the required method is showPrevious() |
动画相关方法：
|
Animation Related Methods |
Description |
|---|---|
| loadAnimation(Context context, int id) |
This method is used whenever we need to define an object of Animation class through AnimationUtilities class by calling a static method loadAnimation. |
| setInAnimation(loadIn) | In order to set the animation of the appearance of the object on the screen |
| setOutAnimation(out) |
When we show the next view, first view has to be removed and that is done by using setOutAnimation() |
| setFactory(ViewFactory factory) |
It is used to create a new view for ViewSwitcher. The old one is replaced and a new view is created by using this method. |
ViewSwitcher的属性
通过查看属性以及对项目有帮助的方法。
|
Attributes |
Description |
|---|---|
| id | To uniquely identify a ViewSwitcher. |
|
padding
|
This attribute is used to set the padding from the left, right, the top or bottom side of a ViewSwitcher
|
| background |
Set the background of a ViewSwitcher by this method. To make a pleasing appeal, the background has to be set. |
我们可以在背景的背景中设置颜色或可绘制对象：
XML格式
步骤3：使用MainActivity。 Java文件
转到MainActivity。 Java文件并参考以下代码。下面是MainActivity的代码。 Java文件。在代码内部添加了注释，以更详细地了解代码。
Java
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;
import androidx.appcompat.app.AppCompatActivity;
public class MainActivity extends AppCompatActivity {
private ViewSwitcher simpleViewSwitcher;
Button btnNext, btnPrev;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// get The references of Button and ViewSwitcher
btnNext = (Button) findViewById(R.id.buttonNext);
btnPrev = (Button) findViewById(R.id.buttonPrevious);
// get the reference of ViewSwitcher
simpleViewSwitcher = (ViewSwitcher) findViewById(R.id.simpleViewSwitcher);
// Declare in and out animations and load them using AnimationUtils class
Animation in = AnimationUtils.loadAnimation(this, android.R.anim.slide_in_left);
Animation out = AnimationUtils.loadAnimation(this, android.R.anim.slide_out_right);
// set the animation type to ViewSwitcher
simpleViewSwitcher.setInAnimation(in);
simpleViewSwitcher.setOutAnimation(out);
// ClickListener for NEXT button
// When clicked on Button ViewSwitcher will switch between views
// The current view will go out and next view will come in with specified animation
btnNext.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
// show the next view of ViewSwitcher
simpleViewSwitcher.showNext();
}
});
btnPrev.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
// show the previous view of ViewSwitcher
simpleViewSwitcher.showPrevious();
}
});
}
}
输出
在android studio中运行android代码时，我们可以获取输出，如附件视频所示。这是一个有用的功能，可在许多android应用程序中使用。