Android Button และการรับ Event ด้วย OnClick

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

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

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

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// Button เฉพาะอักษร
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Button button = new Button(this);
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button.setLayoutParams(new ActionBar.LayoutParams(
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        ViewGroup.LayoutParams.WRAP_CONTENT,
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        ViewGroup.LayoutParams.WRAP_CONTENT));
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button.setText("This is Button");
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// Button ด้วยรูปภาพ
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ImageButton imageButton = new ImageButton(this);
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imageButton.setLayoutParams(new ActionBar.LayoutParams(
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        ViewGroup.LayoutParams.WRAP_CONTENT,
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        ViewGroup.LayoutParams.WRAP_CONTENT));
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imageButton.setImageResource(R.drawable.ic_launcher);
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// Button ทั้งรูปและตัวอักษร
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Button button2 = new Button(this);
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button2.setLayoutParams(new ActionBar.LayoutParams(
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        ViewGroup.LayoutParams.WRAP_CONTENT,
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        ViewGroup.LayoutParams.WRAP_CONTENT));
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button2.setText("I'm Button");
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button2.setCompoundDrawables(getResources().
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        getDrawable(R.drawable.ic_launcher), null, null, null);

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<RelativeLayout
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    xmlns:android="http://schemas.android.com/apk/res/android"
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    android:layout_width="match_parent"
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    android:layout_height="match_parent"
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    android:padding="16dp">
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    <Button
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        android:id="@+id/button1"
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        android:layout_width="match_parent"
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        android:layout_height="wrap_content"
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        android:layout_alignParentLeft="true"
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        android:text="Button1"/>
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    <Button
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        android:id="@+id/button2"
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        android:layout_width="match_parent"
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        android:layout_height="wrap_content"
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        android:text="Button2"
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        android:layout_below="@+id/button1"
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        android:layout_marginTop="32dp"/>
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    <Button
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        android:id="@+id/button3"
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        android:layout_width="match_parent"
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        android:layout_height="wrap_content"
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        android:text="Button3"
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        android:layout_below="@+id/button2"
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        android:layout_marginTop="32dp"/>
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    <Button
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        android:id="@+id/button4"
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        android:layout_width="match_parent"
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        android:layout_height="wrap_content"
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        android:text="Button4"
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        android:layout_below="@+id/button3"
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        android:layout_marginTop="32dp"/>
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</RelativeLayout>

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

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

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public class MainActivity extends ActionBarActivity implements View.OnClickListener {
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    @Override
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    protected void onCreate(Bundle savedInstanceState) {
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        super.onCreate(savedInstanceState);
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        setContentView(R.layout.activity_main);
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    }
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    public void showMessage(View view) {
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        Toast.makeText(this, "Button1 Clicked!", Toast.LENGTH_SHORT).show();
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    }
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    @Override
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    public void onClick(View v) {
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        Toast.makeText(this, "Button2 Clicked!", Toast.LENGTH_SHORT).show();
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    }
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}

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

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

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

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