Android Common UI Components-Button

button is one of the most common UI components in Android, very small but most commonly used in development. It is typically used in conjunction with a listener to trigger some specific events. Button inherits the TextView. Its function is to provide a button, this button can be clicked by the user, when the user action on the button, trigger the corresponding event, such as Click, Touch. In general, for a button, the most used is the Click event, the button indirectly inherits from view, and all the events in the Android UI are defined in the view.

Example: Buttondemo
operating effect:


Code Listing:
Layout file: Main.xml

<?xml version= "1.0" encoding= "Utf-8"? ><linearlayout xmlns:android= "http://schemas.android.com/apk/res/ Android "    android:orientation=" vertical "    android:layout_width=" fill_parent "    android:layout_height=" Fill_parent "    >    <button android:id=" @+id/button1 "        android:layout_width=" Fill_parent        " android:layout_height= "Wrap_content" android:text= "Button1"/>    <button android:id= "@+id/button2"        Android:layout_width= "Fill_parent"        android:layout_height= "wrap_content" android:text= "Button2"/></ Linearlayout>

Java source code file: Activitybutton.java

Package Com.rainsong.buttondemo;import Android.app.activity;import Android.os.bundle;import Android.view.View; Import Android.view.view.onclicklistener;import Android.widget.button;import Android.widget.toast;public class    Activitybutton extends activity{Button btn1;        Button btn2;    Onclicklistener Listener1;    Onclicklistener Listener2; /** called when the activity is first created.        */@Override public void OnCreate (Bundle savedinstancestate) {super.oncreate (savedinstancestate);        Setcontentview (R.layout.main); Listener1 = new Onclicklistener () {public void OnClick (View v) {toast.maketext (Activitybutton.            This, "Button1 clicked", Toast.length_short). Show ();        }        }; Listener2 = new Onclicklistener () {public void OnClick (View v) {toast.maketext (Activitybutton.            This, "Button2 clicked", Toast.length_short). Show ();        }        }; BTN1 = (Button) Findviewbyid (r.id. button1);        Btn1.setonclicklistener (Listener1);        BTN2 = (Button) Findviewbyid (R.id.button2);    Btn2.setonclicklistener (LISTENER2); }}

API Knowledge points
Activity
public class
Activity
Extends Contextthemewrapper
Implements COMPONENTCALLBACKS2 Keyevent.callback Layoutinflater.factory2 View.oncreatecontextmenulistener Window.callback

View Findviewbyid (int id)
Finds A view that is identified by the id attribute from the XML is processed in OnCreate (Bundle).

void Setcontentview (int layoutresid)
Set the activity content from a layout resource.

View
public class
View
Extends Object
Implements Drawable.callback Keyevent.callback Accessibilityeventsource

void Setonclicklistener (View.onclicklistener l)
Register a callback to being invoked when the this view is clicked.

Button
public class
Button
Extends TextView

View.onclicklistener
public static interface
View.onclicklistener

abstract void OnClick (View v)
Called when a view has been clicked.

Toast
public class
Toast
Extends Object

Constants
int Length_long showthe View or text notification for a LONG period of time.
int Length_short showthe View or text notification for a short period of time.

Static Toast
Maketext (context context, int resId, int duration)
Make a standard toast, the just contains a text view with the text from a resource.

Static Toast
Maketext (Context context, charsequence text, int duration)
Make a standard toast, that just contains a text view.

void
Show ()
Show The View for the specified duration.

Android Common UI Components-Button