How to store checkbox value with shared preference?

In my app I am trying to store checkbox value in shared preference,when user click on btn checkbox value should store in shared preference..But whenever again i open my app checkbox status got null,following is my snippet code,what is the issue with this code..

 public class ConfigurationsActivity extends Activity {

ImageView img_navigation_link;
private Button btn_set_configs;
String who;
private EditText edt_api_url, edt_username, edt_password;
private CheckBox edt_Autenticate;
private Button btn_Save_settings;
private TextView txtuname;
private TextView txtpname;
private TextView txtauth;
int aj;

@Override
protected void onCreate(Bundle savedInstanceState) {
    // TODO Auto-generated method stub
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_configuaration);


    edt_api_url = (EditText) findViewById(R.id.edt_api_url);

    initialize();
    onclickWidgets();


    if(consts.pref.getBoolean("checkbox", false))
    {
        edt_Autenticate.setChecked(true);

    }
    else
    {
        edt_Autenticate.setChecked(false);

    }

    edt_Autenticate.setOnCheckedChangeListener(new OnCheckedChangeListener() {

        @Override
        public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
            // TODO Auto-generated method stub
            if (isChecked) {

                aj=1;
                System.out.println("when aj 1"+aj);
                //consts.pref = getSharedPreferences("pref", MODE_PRIVATE);
                consts.pref.edit().putBoolean("check", true).commit();

            }
            else
            {
                aj=2;
                System.out.println("when aj 2"+aj);

            }

        }
    });


    // imgone=(RelativeLayout)findViewById();
}

private void initialize() {

    consts.pref = getSharedPreferences("pref", MODE_PRIVATE);
    consts.editor = consts.pref.edit();
    who = consts.pref.getString("who", "");
    consts.Base_URL = consts.pref.getString(consts.Base_URL, consts.Base_URL);
    edt_api_url.setText(consts.Base_URL);


    TextView current_office_name = (TextView) findViewById(R.id.txt_configuration);
    current_office_name.setText(consts.pref.getString("office_name", ""));
    //
    Log.d("api url configurations", consts.pref.getString(consts.Base_URL, consts.Base_URL));

    txtuname = (TextView) findViewById(R.id.txt_username);
    txtpname = (TextView) findViewById(R.id.txt_password);
    txtauth = (TextView) findViewById(R.id.txt_Autenticate);

    edt_username = (EditText) findViewById(R.id.edt_username);
    edt_password = (EditText) findViewById(R.id.edt_password);
    edt_Autenticate = (CheckBox) findViewById(R.id.edt_Autenticate);
    btn_Save_settings = (Button) findViewById(R.id.btn_Save_settings);

//  System.out.println(" check nu status "+consts.pref.getBoolean("checkbox", false));



    if (who.equals("config")) {
        edt_username.setVisibility(View.GONE);
        edt_password.setVisibility(View.GONE);
        edt_Autenticate.setVisibility(View.GONE);
        txtpname.setVisibility(View.GONE);
        txtuname.setVisibility(View.GONE);
        txtauth.setVisibility(View.GONE);

    } else if (who.equals("user")) {

        edt_api_url.setKeyListener(null);


    }
    img_navigation_link = (ImageView) findViewById(R.id.img_navigation_link);
    img_navigation_link.setOnClickListener(new View.OnClickListener() {

        @Override
        public void onClick(View v) {
            // TODO Auto-generated method stub

            Intent intent = new Intent(ConfigurationsActivity.this, MainMenu.class);
            startActivity(intent);
            ConfigurationsActivity.this.finish();
        }
    });

    btn_Save_settings.setOnClickListener(new OnClickListener() {

        @Override
        public void onClick(View v) {
            // TODO Auto-generated method s
            if (who.equals("config")) {

                if (edt_api_url.getText().toString().trim().equals("")) {

                    Toast.makeText(getApplicationContext(), "Endereço API inválido", Toast.LENGTH_SHORT).show();

                } else {

                    {
                        consts.editor.putString(consts.Base_URL, edt_api_url.getText().toString().trim());
                        consts.editor.commit();

                        Toast.makeText(getApplicationContext(), "As configurações foram guardadas",
                                Toast.LENGTH_SHORT).show();
                    }
                }

            } else if (who.equals("user")) {
                if (edt_username.getText().toString().trim().equals("")
                        && edt_password.getText().toString().trim().equals("")) {
                    Toast.makeText(getApplicationContext(), "Digite nome de usuário e senha", Toast.LENGTH_SHORT)
                            .show();
                } else {

                    if (edt_username.getText().toString().trim().equals(consts.pref.getString("user_name", ""))
                            && edt_password.getText().toString().trim()
                                    .equals(consts.pref.getString("user_password", ""))) {


                        if(aj==1)
                        {
                            consts.editor.putBoolean("checkbox", true).commit();
                            consts.editor.commit();
                        }
                        else
                        {
                            consts.editor.putBoolean("checkbox", false).commit();
                            consts.editor.commit();
                        }


                        Toast.makeText(getApplicationContext(), "As configurações foram guardadas",
                                Toast.LENGTH_SHORT).show();


                    } else {
                        Toast.makeText(getApplicationContext(), "Nome de usuário e senha errada",
                                Toast.LENGTH_SHORT).show();
                    }

                }
            }
        }
    });

}

private void onclickWidgets() {
}