Làm việc với checkBox trong android

package com.example.macbookpro.kpsoncheckbox;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.CheckBox;
import android.widget.Toast;

public class MainActivity extends AppCompatActivity {
    CheckBox chkXemPhim, chkNgheNhac, chkDocSach;
    Button btnDongY;
    @Override    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        chkXemPhim = (CheckBox) findViewById(R.id.checkBoxXemPhim);
        chkNgheNhac = (CheckBox) findViewById(R.id.checkBoxNgheNhac);
        chkDocSach = (CheckBox) findViewById(R.id.checkBoxDocSach);
        btnDongY = (Button) findViewById(R.id.buttonDongY);



        btnDongY.setOnClickListener(new View.OnClickListener() {
            @Override            public void onClick(View v) {
                String chuoi = "So thich cua ban: ";
                if(chkXemPhim.isChecked())chuoi+= chkXemPhim.getText()+" ";
                if(chkNgheNhac.isChecked())chuoi+=chkNgheNhac.getText()+" ";
                if(chkDocSach.isChecked())chuoi+= chkDocSach.getText();
                Toast.makeText(MainActivity.this, chuoi,Toast.LENGTH_LONG).show();
            }
        });



    }
}