我有以下代碼:爲什麼我的視圖沒有改變?
public class DrawView extends View {
Paint paint = new Paint();
public DrawView(Context context) {
super(context);
}
@Override
public void onDraw(Canvas canvas) {
paint.setColor(Color.BLACK);
paint.setStrokeWidth(3);
canvas.drawRect(30, 30, 80, 80, paint);
paint.setStrokeWidth(0);
paint.setColor(Color.CYAN);
canvas.drawRect(33, 60, 77, 77, paint);
paint.setColor(Color.YELLOW);
canvas.drawRect(33, 33, 77, 60, paint);
}
}
和主類:
public class MainActivity extends Activity {
DrawView drawView;
Button btn;
View view;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
btn = (Button) findViewById(R.id.button1);
view = (View) findViewById(R.id.view1);
btn.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
generate();
}
});
}
public void generate() {
drawView = new DrawView(this);
drawView.setBackgroundColor(Color.WHITE);
view = drawView;
}
}
問題是:當我按一下按鈕,我不能看到DrawView
和我dont't知道爲什麼。
編輯:這裏是XML代碼:
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/root"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context=".MainActivity" >
<Button
android:id="@+id/button1"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="@string/generate" />
<View
android:id="@+id/view1"
android:layout_width="wrap_content"
android:layout_height="wrap_content" />
</LinearLayout>
您需要通過XML或代碼將自定義View添加到View層次結構中。 –
您必須通過addView方法將您的DrawView添加到某個ViewGroup父項 – pskink