Android中利用LinearLayout动态添加控件

在androidUI布局中，一般都是利用xml来布局控件，这是比较方便和直观的，但是有时却需要动态生成，下面就举2个简单例子来说明怎么动态添加控件：

1.动态添加2个垂直排列的Button

@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
//setContentView(R.layout.main);
final LinearLayout layout2=new LinearLayout(this);
layout2.setOrientation(LinearLayout.VERTICAL);
Button btn1=new Button(this);
setContentView(layout2);
Button btn2=new Button(this);
btn1.setText("Button1");
btn2.setText("Button2");
layout2.addView(btn1);
layout2.addView(btn2);

setContentView(layout2);
}

final LinearLayout layout2=new LinearLayou(this);

定义一个LinearLayout ，参数为context在这儿即为this

layout2.setOrientation(LinearLayout.VERTICAL);

设置layout格式为vertical，竖直排列

2.在Button的click事件中动态添加一个button

OnClickListener listen1;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
//setContentView(R.layout.main);
final LinearLayout layout2=new LinearLayout(this);
layout2.setOrientation(LinearLayout.VERTICAL);
Button btn1=new Button(this);
setContentView(layout2);
Button btn2=new Button(this);
btn1.setText("Button1");
btn2.setText("Button2");
layout2.addView(btn1);
layout2.addView(btn2);
listen1 = new OnClickListener() {
public void onClick(View v) {
setTitle("点击button1 ");
Button btn3=new Button(v.getContext());
layout2.addView(btn3);
btn3.setText("Button3");

}
};
btn1.setOnClickListener(listen1);
}

与上一例子区别就是，在Button的OnClickListener中动态添加控件，需要注意的一点是 Button btn3=new Button(v.getContext);参数v.getContext为当前view的context，为什么例子1中用this作为context呢，呵呵，这是因为this即当前的activity，而activity又是context的子类，所以this就可以直接作为activity了。

查了下，context派生的类有：

java.lang.Object
↳	android.content.Context

Known Direct Subclasses ContextWrapper , MockContext ContextWrapper Proxying implementation of Context that simply delegates all of its calls to another Context. MockContext A mock Context class.

Known Indirect Subclasses

AbstractInputMethodService
,
Activity
,
ActivityGroup
,
AliasActivity
,
Application
,
ContextThemeWrapper
,
ExpandableListActivity
,
InputMethodService
,
IntentService
,
IsolatedContext
,
LauncherActivity
,
ListActivity
,
MockApplication
,
MutableContextWrapper
,
PreferenceActivity
,
RenamingDelegatingContext
,
Service
,
TabActivity