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

view plain

@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

view plain
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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

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