问Android初学者(添加按钮)

EN

    <?xml version="1.0" encoding="utf-8"?>
    <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_height="fill_parent" android:layout_width="fill_parent"
    android:layout_gravity="center_horizontal" android:orientation="horizontal"
    android:layout_weight="1" android:id="@+id/singleEmployee"
    android:background="#ffffff">
    <TextView android:text="TextView" android:id="@+id/textView1"
        android:layout_width="wrap_content" android:layout_height="wrap_content"></TextView>
    <TextView android:text="TextView" android:id="@+id/textView2"
        android:layout_width="wrap_content" android:layout_height="wrap_content"></TextView>
    <TextView android:text="TextView" android:id="@+id/textView3"
        android:layout_width="wrap_content" android:layout_height="wrap_content"></TextView>
    <Button android:text="Button" android:id="@+id/button1"
        android:layout_width="wrap_content" android:layout_height="wrap_content"></Button>
</LinearLayout>

public class HelperStackOverflowActivity extends Activity {
/** Called when the activity is first created. */
TextView tv1,tv2,tv3;
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.testing);
    tv1 = (TextView)findViewById(R.id.textView1);
    tv2 = (TextView)findViewById(R.id.textView2);
    tv3 = (TextView)findViewById(R.id.textView3);
    tv1.setText("Hello");
    tv2.setText("World");
    Button add = (Button)findViewById(R.id.button1);
    add.setOnClickListener(new View.OnClickListener() {

        @Override
        public void onClick(View v) {
            tv3.setText("");
            String tvValue1 = tv1.getText().toString();
            String tvValue2 = tv2.getText().toString();
            tv3.setText("Value of First Text is: "+tvValue1+".And the value of second TextView is: "+tvValue2);
        }
    });
}