view问题

package com.example.bringtofrontdemo;
import android.app.Activity;
import android.os.Bundle;
import android.widget.Button;
import android.widget.FrameLayout;
public class MainActivity extends Activity {
private Button button;
private FrameLayout rootFrameLayout;
@Override
protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); button=(Button)findViewById(R.id.textviewId); Button secondButton=new Button(this); rootFrameLayout=(FrameLayout)findViewById(R.id.root); secondButton.setWidth(100); secondButton.setHeight(50); secondButton.setText("签名阿德。"); rootFrameLayout.addView(secondButton); //这样原先的那个button就会到了最前面。 button.bringToFront(); //android4.4之前的版本需要让view的父控件调用这两个方法使其重绘。 rootFrameLayout.requestLayout(); rootFrameLayout.invalidate(); } }

activity_main.xml

<Button  
    android:id="@+id/textviewId"  
    android:layout_width="match_parent"  
    android:layout_height="wrap_content"  
    android:text="@string/hello_world" />  

ng/article/details/40450753