Android 中如何处理checkbox的选中、未选中

xml页面布局

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:Android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    >
<CheckBox android:id="@+id/plain_cb"
 android:text="Plain" 
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    />
<CheckBox android:id="@+id/bold_cb"
 android:text="Bold" 
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:textstyle="bold"
    />   
<CheckBox android:id="@+id/serif_cb"
 android:text="Serif"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:typeface="serif"
    />   
<CheckBox android:id="@+id/italic_cb"
 android:text="Italic"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:textstyle="italic"
    />
<Button android:id="@+id/get_view_button"
 android:layout_width="wrap_content"
 android:layout_height="wrap_content"
 android:text="获取CheckBox的值"
/>
   
</LinearLayout>
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java类:

package com.zgct.activity;

import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.CheckBox;

public class CheckBoxActivity extends Activity {
 CheckBox plain_cb;
 CheckBox serif_cb;
 CheckBox italic_cb;
 CheckBox bold_cb;

 @Override
 protected void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setTitle("CheckBoxActivity");
  setContentView(R.layout.check_box);
  find_and_modify_text_view();
 }
 
 private void find_and_modify_text_view(){
  plain_cb = (CheckBox) findViewById(R.id.plain_cb);
  serif_cb = (CheckBox) findViewById(R.id.serif_cb);
  italic_cb = (CheckBox) findViewById(R.id.italic_cb);
  bold_cb = (CheckBox) findViewById(R.id.bold_cb);
  
  Button get_view_button = (Button)findViewById(R.id.get_view_button);
  get_view_button.setOnClickListener(get_view_button_listener);
 }
 
    private Button.OnClickListener get_view_button_listener = new Button.OnClickListener(){
     public void onClick(View v){
      String r = "";
      if(plain_cb.isChecked()){
       r = r + "," + plain_cb.getText();
      }
      if(serif_cb.isChecked()){
       r = r + "," + serif_cb.getText();
      }
      if(bold_cb.isChecked()){
       r = r + "," + bold_cb.getText();
      }
      if(italic_cb.isChecked()){
       r = r + "," + italic_cb.getText();
      }
      setTitle("Checked: " + r);
     }
    };
}