Android Shared Preference

1. Application
public class BaseApplication extends Application {

    @Override
    public void onCreate() {
        super.onCreate();

        SharedPreferences pref = getSharedPreferences("settings", MODE_PRIVATE);
        SharedPreferences.Editor editor = pref.edit();

        editor.putString("display-name", "John Doe");
        editor.putBoolean("safe-mode", true);

        editor.apply();
    }
}

2. Activity
@Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        ButterKnife.bind(this);
    }

    @BindView(R.id.tvShowPreference) TextView tvShowPreference;

    @OnClick(R.id.btnGetPref)
    public void showPref(){
        SharedPreferences pref = getApplicationContext()
                .getSharedPreferences("settings", MODE_PRIVATE);
        this.displayname = pref.getString("display-name", "");

        this.tvShowPreference.setText(this.displayname);
    }

3. Android Manifest
<application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/AppTheme"
        android:name=".BaseApplication">