Android Button และการรับ Event ด้วย OnClick

<Button
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="This is Button" />

<ImageButton
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:src="@drawable/ic_launcher" />

<Button
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="@string/I'm Button"
    android:drawableLeft="@drawable/ic_launcher" />

// Button เฉพาะอักษร
Button button = new Button(this);
button.setLayoutParams(new ActionBar.LayoutParams(
        ViewGroup.LayoutParams.WRAP_CONTENT,
        ViewGroup.LayoutParams.WRAP_CONTENT));
button.setText("This is Button");

// Button ด้วยรูปภาพ
ImageButton imageButton = new ImageButton(this);
imageButton.setLayoutParams(new ActionBar.LayoutParams(
        ViewGroup.LayoutParams.WRAP_CONTENT,
        ViewGroup.LayoutParams.WRAP_CONTENT));
imageButton.setImageResource(R.drawable.ic_launcher);

// Button ทั้งรูปและตัวอักษร
Button button2 = new Button(this);
button2.setLayoutParams(new ActionBar.LayoutParams(
        ViewGroup.LayoutParams.WRAP_CONTENT,
        ViewGroup.LayoutParams.WRAP_CONTENT));
button2.setText("I'm Button");
button2.setCompoundDrawables(getResources().
        getDrawable(R.drawable.ic_launcher), null, null, null);

<RelativeLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:padding="16dp">

    <Button
        android:id="@+id/button1"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_alignParentLeft="true"
        android:text="Button1"/>

    <Button
        android:id="@+id/button2"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Button2"
        android:layout_below="@+id/button1"
        android:layout_marginTop="32dp"/>

    <Button
        android:id="@+id/button3"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Button3"
        android:layout_below="@+id/button2"
        android:layout_marginTop="32dp"/>

    <Button
        android:id="@+id/button4"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Button4"
        android:layout_below="@+id/button3"
        android:layout_marginTop="32dp"/>

</RelativeLayout>

<Button
    android:id="@+id/button1"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_alignParentLeft="true"
    android:onClick="showMessage"
    android:text="Button1"/>

public void showMessage(View view) {
    Toast.makeText(this, "Button1 Clicked!", Toast.LENGTH_SHORT).show();
}

public class MainActivity extends ActionBarActivity implements View.OnClickListener {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

    }

    public void showMessage(View view) {
        Toast.makeText(this, "Button1 Clicked!", Toast.LENGTH_SHORT).show();
    }

    @Override
    public void onClick(View v) {
        Toast.makeText(this, "Button2 Clicked!", Toast.LENGTH_SHORT).show();
    }
}

Button button2 = (Button) findViewById(R.id.button2);
button2.setOnClickListener(this);

Button button3 = (Button) findViewById(R.id.button3);
button3.setOnClickListener(new View.OnClickListener() {
    @Override
    public void onClick(View v) {
        Toast.makeText(getApplicationContext(),
                "Button3 Clicked!", Toast.LENGTH_SHORT).show();
    }
});

View.OnClickListener Button4OnClick = new View.OnClickListener() {
    @Override
    public void onClick(View v) {
        Toast.makeText(getApplicationContext(),
                "Button4 Clicked!", Toast.LENGTH_SHORT).show();
    }
};

Button button4 = (Button) findViewById(R.id.button4);
button4.setOnClickListener(Button4OnClick);