Android---20---CheckBox复选框

MainActivity.java:

import android.app.Activity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.CheckBox;
import android.widget.Toast;

public class MainActivity extends Activity implements OnClickListener {
	private CheckBox basketball,football,baseball,pingpang;
	private Button button;
	
	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
		basketball = (CheckBox) findViewById(R.id.basketball);
		baseball = (CheckBox) findViewById(R.id.baseball);
		football = (CheckBox) findViewById(R.id.football);
		pingpang = (CheckBox) findViewById(R.id.pingpang);
		button = (Button) findViewById(R.id.button);
		button.setOnClickListener(this);
	}

	@Override
	public void onClick(View v) {
		// TODO Auto-generated method stub
		String s = "";
		boolean flag = false;
		if (basketball.isChecked()){
			s += basketball.getText().toString();
			flag = true;
		}
		if (baseball.isChecked()){
			s += baseball.getText().toString();
			flag = true;
		}
		if (football.isChecked()){
			s += football.getText().toString();
			flag = true;
		}
		if (pingpang.isChecked()){
			s += pingpang.getText().toString();
			flag = true;
		}
		if (flag == false){
			Toast.makeText(MainActivity.this, "没有任何选项", 0).show();
		}else {
			Toast.makeText(MainActivity.this, s, 0).show();
		}
	}
}

activity_main.xml:

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context="com.example.checkboxdemo2.MainActivity" >

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="选择爱好" />

    <LinearLayout
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:orientation="vertical" >

        <CheckBox
            android:id="@+id/basketball"
            android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            android:text="篮球" />

        <CheckBox
            android:id="@+id/football"
            android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            android:text="足球" />

        <CheckBox
            android:id="@+id/baseball"
            android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            android:text="网球" />

        <CheckBox
            android:id="@+id/pingpang"
            android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            android:text="乒乓球" />
    </LinearLayout>

    <Button
        android:id="@+id/button"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:text="确定" />

</LinearLayout>