Android SDK Tutorial: Button onClick Event

Making your app notice when a button was clicked is pretty simple, the code am giving you here is what I found to be the shortest method to do so.

The Result

We will make a button that updates a label with the current date when you click it. Pictures below.

The app before a button click

Now when you the click button:
Android SDK Tutorial: Button onClick Event_第1张图片

After the click: the text was updated to the current date.

The Button Click Class (HelloAndroid.java)

package com.example.helloandroid;import java.util.Date;import android.app.Activity;import android.os.Bundle;import android.view.View;import android.widget.TextView;public class HelloAndroid extends Activity{TextView date;@Overridepublic void onCreate(Bundle savedInstanceState){super.onCreate(savedInstanceState);setContentView(R.layout.main);date=(TextView)findViewById(R.id.dateText);}public void showNewDate(View v){date.setText(new Date().toString());}}

The Android Manifest(AndroidManifest.xml)

Don’t forget to change android:minSdkVersion to the version you are using.

<?xml version="1.0" encoding="utf-8"?><manifest xmlns:android="http://schemas.android.com/apk/res/android"      package="com.example.helloandroid"      android:versionCode="1"      android:versionName="1.0">    <uses-sdk android:minSdkVersion="13" />    <application android:icon="@drawable/icon" android:label="@string/app_name" android:debuggable="true">        <activity android:name=".HelloAndroid"                  android:label="@string/app_name">            <intent-filter>                <action android:name="android.intent.action.MAIN" />                <category android:name="android.intent.category.LAUNCHER" />            </intent-filter>        </activity>    </application></manifest>

The Layout(main.xml)

The line android:onClick is saving us from typing many more JAVA code lines. The value is the method in the JAVA file we want to execute when a user clicks the button.

<?xml version="1.0" encoding="utf-8"?><LinearLayoutxmlns:android="http://schemas.android.com/apk/res/android"android:layout_width="fill_parent"android:layout_height="fill_parent"><TextViewandroid:text="You haven't clicked"android:id="@+id/dateText"android:layout_width="wrap_content"android:layout_height="wrap_content" /><Button    android:id="@+id/button"android:layout_width="wrap_content"android:layout_height="wrap_content"android:text="Click Me"  android:onClick="showNewDate"/></LinearLayout>

The Result

The Button Click Class (HelloAndroid.java)

The Android Manifest(AndroidManifest.xml)

The Layout(main.xml)

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