问题
I want to use ViewStub in android, so please help me. I have created
ViewStub stub = new ViewStub;
View inflated = stub.inflate();
How to use it programmatically?
回答1:
Like the documentation says, ViewStub
is a View
that is inflated lazily.
You can declare a ViewStub
in an XML file like this:
<ViewStub android:id="@+id/stub"
android:inflatedId="@+id/subTree"
android:layout="@layout/mySubTree"
android:layout_width="120dip"
android:layout_height="40dip" />
The android:layout
attribute is a reference to the View
that will be inflated next to a call of inflate()
. So
ViewStub stub = (ViewStub) findViewById(R.id.stub);
View inflated = stub.inflate();
When the method inflate()
is invoked the ViewStub
is removed from its parent and replaced with the right View
(the root view of mySubTree
layout).
If you want to do this progammatically then your code should be something like:
ViewStub stub = new ViewStub(this);
stub.setLayoutResource(R.layout.mySubTree);
stub.inflate();
回答2:
Simply a ViewStub is used to increase efficiency of rendering layout. By using ViewStub, manually views can be created but not added to view hierarchy. At the runtime, can be easily inflated, while ViewStub is inflated, the content of the viewstub will be replaced the defined layout in the viewstub.
activity_main.xml we defined viewstub but not created first.
Simple example gives better understanding,
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/content"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical" >
<Button
android:id="@+id/btn1"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="create the view stub" />
<Button
android:id="@+id/btn2"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="Hide the stub." />
<RelativeLayout
android:layout_width="fill_parent"
android:layout_height="0dp"
android:layout_weight="1" >
<ViewStub
android:id="@+id/stub_import"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:inflatedId="@+id/content_import"
android:layout="@layout/splash" />
</RelativeLayout>
</LinearLayout>
At runtime, when we inflate, the content will be replaced with the layout defined in the viewstub.
public class MainActivity extends Activity {
Button b1 = null;
Button b2 = null;
ViewStub stub = null;
TextView tx = null;
int counter = 0;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
b1 = (Button) findViewById(R.id.btn1);
b2 = (Button) findViewById(R.id.btn2);
b1.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
if (stub == null) {
stub = (ViewStub) findViewById(R.id.stub_import);
View inflated = stub.inflate();
tx = (TextView) inflated.findViewById(R.id.text1);
tx.setText("thanks a lot my friend..");
}
}
});
b2.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
if (stub != null) {
stub.setVisibility(View.GONE);
}
}
});
}
So, Lets look at again the view hierarchy,
when we inflate the viewstub, it will be removed from the view hierarchy.
回答3:
Here is an example for show/hide and change data of ViewStub
at run time
activity_main.xml
<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<Button
android:id="@+id/buttonShow"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Show View Stub"/>
<Button
android:id="@+id/buttonHide"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Hide View Stub"/>
<ViewStub
android:id="@+id/viewStub"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout="@layout/layout_of_view_stub"
/>
</LinearLayout>
layout_of_view_stub.xml
<TextView
android:id="@+id/textInViewStub"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
/>
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="ViewStub Button"
/>
MainActivity.java
public class MainActivity extends AppCompatActivity {
private ViewStub viewStub;
private Button buttonShow;
private Button buttonHide;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
buttonShow = findViewById(R.id.buttonShow);
buttonHide = findViewById(R.id.buttonHide);
buttonShow.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
showViewStub();
}
});
buttonHide.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
hideViewStub();
}
});
}
private void showViewStub() {
if (viewStub == null) {
viewStub = findViewById(R.id.viewStub);
// If you want to change data of ViewStub at runtime, you can do like this
View inflatedView = viewStub.inflate();
TextView textViewInViewStub = inflatedView.findViewById(R.id.textInViewStub);
textViewInViewStub.setText("ABC");
}
viewStub.setVisibility(View.VISIBLE);
}
private void hideViewStub() {
if (viewStub == null) {
return;
}
viewStub.setVisibility(View.GONE);
}
}
来源:https://stackoverflow.com/questions/11577777/how-to-use-view-stub-in-android