I want to save a flag for recognizing that my app is run for the first time or not. For this simple job I don't want to create database..

Is there a simple option to do this? I want to save and read little pieces of information only.

Use SharedPreferences.

SharedPreferences preferences = getSharedPreferences("prefName", MODE_PRIVATE);
SharedPreferences.Editor edit= preferences.edit();

edit.putBoolean("isFirstRun", false);
edit.commit();

Use sharedPreference or files to save the data but better option is sharedPreference.

For Retrieving

SharedPreferences settings = getSharedPreferences(PREFS_NAME, 0);
boolean silent = settings.getBoolean("silentMode", false);

For Saving

SharedPreferences settings = getSharedPreferences(PREFS_NAME, 0);
SharedPreferences.Editor editor = settings.edit();
editor.putBoolean("silentMode", true);
editor.commit();

A proper way to do this is by using the Android class SharedPreferences which is used for things like this.

Storing Settings

SharedPreferences settings = getSharedPreferences(NAME_OF_PREFERENCES, MODE_PRIVATE);
SharedPreferences.Editor editor = settings.edit();
editor.putBoolean("appPreviouslyStarted", true);
editor.apply();

Don't forget to apply or your mutations to the settings won't be saved!

You can create multiple settings by using different NAME_OF_PREFERENCES. The settings are stored on the device so will be available after closing the application.

When you try to retrieve NAME_OF_PREFERENCES that is not already created, you create a new one. See more behavior like this here.

apply() versus commit()

You can use editor.apply() as well as editor.commit(), the only difference is that apply() does not return a boolean value with if the edit was successful or not. editor.apply() is therefor faster and more commonly used.

What is MODE_PRIVATE

You can see all about the different modes here. For your case MODE_PRIVATE is fine.

Retrieving settings

SharedPreferences settings = getSharedPreferences(NAME_OF_PREFERENCES, MODE_PRIVATE);
boolean silent = settings.getBoolean("silentMode", false);

When retrieving a settings from a SharedPreferences object you always have to specify a default value which will be returned when the setting was not found. In this case that's false.

I suggest you to go for SharedPreference persistent storage. Its very easy and fast storing/retrival for small amount of information.

See the code to get the value from SharedPreference

   // Restore preferences
   SharedPreferences settings = getSharedPreferences(PREFS_NAME, 0);
   boolean silent = settings.getBoolean("silentMode", false);
   setSilent(silent);

and to Store value in SharedPreference

 // We need an Editor object to make preference changes.
  // All objects are from android.context.Context
  SharedPreferences settings = getSharedPreferences(PREFS_NAME, 0);
  SharedPreferences.Editor editor = settings.edit();
  editor.putBoolean("silentMode", mSilentMode);

You can do one class for example: (like a object for instance)

import android.content.Context;
import android.content.SharedPreferences;


public class SettingsMain {

    Context context;
    SharedPreferences preferences;
    SharedPreferences.Editor editor;

    private static final String PREFER_NAME = "settingsMain";
    public static final String KEY_VIBRATE = "switchVibrate";

    public SettingsMain(Context context) {
        this.context = context;
        setPreferences();
    }

    private void setPreferences(){
        preferences = context.getSharedPreferences(PREFER_NAME, context.MODE_PRIVATE);
        editor = preferences.edit();
    }

    public void cleanPreferences(){
        editor.clear();
        editor.commit();
    }

    public void setStatusVibrate(Boolean status){
        editor.putBoolean(KEY_VIBRATE, status);
        editor.commit();
    }
    public Boolean getstatusVibrate(){
        return preferences.getBoolean(KEY_VIBRATE, true);
    }
}

On your activity call:

public class Home extends AppCompatActivity {


    private SettingsMain settings;
    private SwitchCompat switchVibrate;

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


        setResources();
        getSettings();

    }

    private void setResources(){

        switchVibrate = (SwitchCompat) findViewById(R.id.master_main_body_vibrate_switch);
        switchVibrate.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
            @Override
            public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
                settings.setStatusVibrate(isChecked);
            }
        });
    }

    private void getSettings(){
        settings = new SettingsMain(this);
        switchVibrate.setChecked(settings.getstatusVibrate());
    }

}

What about using static variables globally?

You can do this as given in this tutorial. I know handling Content providers are unnecessary just to keep some flags.

Else you can check out Shared Preferences provided by Android. Here's a good example to get started.

This would be my recommendation.

来源：https://stackoverflow.com/questions/15385117/save-little-information-as-setting-in-android-like-first-time-that-app-is-run

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