初学Android,简述View组件(三)

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Android所有的UI组件都是建立在View,ViewGroup基础之上，ViewGroup又是继承View的子类，作为容器来盛装其它组件，而ViewGroup除了可以包含普通View组件外，还可以再次包含ViewGroup组件，也就是可以嵌套使用。

ViewGroup容器控制其子组件的分布依赖于ViewGroup.LayoutParams,ViewGroup.MarginLayoutParams两个内部类。在些不详述它们的API了，写出来没什么意义，到处都有。

下面用编程方式(不使用XML布局文件)开发UI界面

class="language-java">package WangLi.UI.Space;

import class="tags" href="/tags/ANDROID.html" title=android>android.app.Activity;
import class="tags" href="/tags/ANDROID.html" title=android>android.os.Bundle;
import class="tags" href="/tags/ANDROID.html" title=android>android.view.View;
import class="tags" href="/tags/ANDROID.html" title=android>android.view.View.OnClickListener;
import class="tags" href="/tags/ANDROID.html" title=android>android.view.ViewGroup;
import class="tags" href="/tags/ANDROID.html" title=android>android.widget.Button;
import class="tags" href="/tags/ANDROID.html" title=android>android.widget.LinearLayout;
import class="tags" href="/tags/ANDROID.html" title=android>android.widget.TextView;

public class UIActivity extends Activity {
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        //创建一个线性布局管理器
        LinearLayout class="tags" href="/tags/LAYOUT.html" title=layout>layout = new LinearLayout(this);
        //设置该Activity显示class="tags" href="/tags/LAYOUT.html" title=layout>layout
        super.setContentView(class="tags" href="/tags/LAYOUT.html" title=layout>layout);
        class="tags" href="/tags/LAYOUT.html" title=layout>layout.setOrientation(LinearLayout.VERTICAL);
        //创建一个TextView
        final TextView show = new TextView(this);
        //创建一个按钮
        Button bn = new Button(this);
        bn.setText("单击我");
        bn.setLayoutParams(new ViewGroup.LayoutParams(ViewGroup.LayoutParams.WRAP_CONTENT,
        		ViewGroup.LayoutParams.WRAP_CONTENT));
        //向Layout容器中添加TextView
        class="tags" href="/tags/LAYOUT.html" title=layout>layout.addView(show);
        //向Layout容器中添加按钮
        class="tags" href="/tags/LAYOUT.html" title=layout>layout.addView(bn);
        //为按钮绑定一个事件监听器
        bn.setOnClickListener(new OnClickListener(){  
            public void onClick(View v)  
            {  
                show.setText("Hello Android ~" + new java.util.Date());  
            }  
        });  
    }
}