java layout

[功能]
大家都有如此需求 即 界面不是固定的 而是在程序中随着一些参数的变化 做实时的改动 那应该怎么做到呢? 在xml 中是不可行的 那在java 中呢?

[原理]
1. android 提供了一些 layout，比如：LinearLayout 我们大家可以运用这些
2. 使用layout: setContentView()


[代码]
1. 一个例子.

public class LayoutAdd1Usage extends Activity {
	private static final int TEXTVIEW_1 = 1;
    private static final int EDITTEXT_1 = 1;
    private static final int BUTTON_1 = 2;
    
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        
        LinearLayout layout = new LinearLayout(this);
        layout.setOrientation(LinearLayout.VERTICAL);
        
        LinearLayout.LayoutParams param =
            new LinearLayout.LayoutParams(LinearLayout.LayoutParams.FILL_PARENT, LinearLayout.LayoutParams.WRAP_CONTENT);
        TextView tv = new TextView(this);
        tv.setText("Hello Android!");
        tv.setGravity(1);
        tv.setId(TEXTVIEW_1);
        layout.addView(tv,param);
        
        LinearLayout.LayoutParams param2 =
            new LinearLayout.LayoutParams(LinearLayout.LayoutParams.FILL_PARENT, LinearLayout.LayoutParams.WRAP_CONTENT);
        EditText edit = new EditText(this);
        edit.setId(EDITTEXT_1);
        
        layout.addView(edit,param2);
        
        LinearLayout.LayoutParams param3 =
            new LinearLayout.LayoutParams(LinearLayout.LayoutParams.WRAP_CONTENT, LinearLayout.LayoutParams.WRAP_CONTENT);
        Button btn = new Button(this);
        btn.setText("OK");
        btn.setId(BUTTON_1);
        
        layout.addView(btn,param3);
        
        setContentView(layout);
                
        
        findViewById(BUTTON_1).setOnClickListener(new OnClickListener(){
			public void onClick(View v) {
				// TODO Auto-generated method stub
				((TextView) findViewById(TEXTVIEW_1)).setText("Welcome to Android world!");
				
			}
        });
        
    }
}

all is simple that no more words to discuss!