andriod CheckBox

<?xml version="1.0" encoding="UTF-8"?>

    <LinearLayout android:orientation="vertical" android:layout_height="fill_parent" android:layout_width="fill_parent" xmlns:android="http://schemas.android.com/apk/res/android">

    <TextView android:layout_height="wrap_content" android:layout_width="fill_parent" android:text="多選控制項：" android:id="@+id/label"/>

    <CheckBox android:layout_height="wrap_content" android:layout_width="wrap_content" android:text="AA" android:id="@+id/plain_cb"/>

    <CheckBox android:layout_height="wrap_content" android:layout_width="wrap_content" android:text="BB" android:id="@+id/serif_cb"/>

    <CheckBox android:layout_height="wrap_content" android:layout_width="wrap_content" android:text="CC" android:id="@+id/bold_cb"/>

    <CheckBox android:layout_height="wrap_content" android:layout_width="wrap_content" android:text="DD" android:id="@+id/italic_cb"/>

    <Button android:layout_height="wrap_content" android:layout_width="wrap_content" android:text="獲取checkbox" android:id="@+id/button1"/>

</LinearLayout>

package com.example.yanlei.mytk;

import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.text.method.HideReturnsTransformationMethod;
import android.text.method.PasswordTransformationMethod;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.Button;
import android.widget.CheckBox;
import android.widget.CompoundButton;
import android.widget.CompoundButton.OnCheckedChangeListener;
import android.widget.TextView;
import android.widget.Toast;


public class MainActivity extends AppCompatActivity {


    private CheckBox plainCB;
    private CheckBox serifCB;
    private CheckBox boldCB;
    private CheckBox italicCB;
    private Button button1;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        // TODO Auto-generated method stub
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        plainCB=(CheckBox)findViewById(R.id.plain_cb);
        serifCB=(CheckBox)findViewById(R.id.serif_cb);
        boldCB=(CheckBox)findViewById(R.id.bold_cb);
        italicCB=(CheckBox)findViewById(R.id.italic_cb);
        button1=(Button)findViewById(R.id.button1);

        button1.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                String result="";
                if(plainCB.isChecked()){
                    result+=plainCB.getText()+"、";
                }
                if(serifCB.isChecked()){
                    result+=serifCB.getText()+"、";
                }
                if(boldCB.isChecked()){
                    result+=boldCB.getText()+"、";
                }
                if(italicCB.isChecked()){
                    result+=italicCB.getText()+"、";
                }
                if(!"".equals(result)){
                    result=result.substring(0,result.length()-1);
                }else{
                    result="你沒有選擇！！！";
                }
                setTitle("Checked:"+result);
            }
        });

    }
}