Android global variable

Question

How can I create global variable keep remain values around the life cycle of the application regardless which activity running.

Answer 1

You can extend the base android.app.Application class and add member variables like so:

public class MyApplication extends Application {

    private String someVariable;

    public String getSomeVariable() {
        return someVariable;
    }

    public void setSomeVariable(String someVariable) {
        this.someVariable = someVariable;
    }
}

In your android manifest you must declare the class implementing android.app.Application (add the android:name=".MyApplication" attribute to the existing application tag):

<application 
  android:name=".MyApplication" 
  android:icon="@drawable/icon" 
  android:label="@string/app_name">

Then in your activities you can get and set the variable like so:

// set
((MyApplication) this.getApplication()).setSomeVariable("foo");

// get
String s = ((MyApplication) this.getApplication()).getSomeVariable();

Answer 2

You can use a Singleton Pattern like this:

package com.ramps;

public class MyProperties {
private static MyProperties mInstance= null;

public int someValueIWantToKeep;

protected MyProperties(){}

public static synchronized MyProperties getInstance() {
        if(null == mInstance){
            mInstance = new MyProperties();
        }
        return mInstance;
    }
}

In your application you can access your singleton in this way:

MyProperties.getInstance().someValueIWantToKeep

Answer 3

This global variable works for my project:

public class Global {
    public static int ivar1, ivar2;
    public static String svar1, svar2;
    public static int[] myarray1 = new int[10];
}


//  How to use other or many activity
Global.ivar1 = 10;

int i = Global.ivar1;

Answer 4

You could use application preferences. They are accessible from any activity or piece of code as long as you pass on the Context object, and they are private to the application that uses them, so you don't need to worry about exposing application specific values, unless you deal with routed devices. Even so, you could use hashing or encryption schemes to save the values. Also, these preferences are stored from an application run to the next. Here is some code examples that you can look at.

Answer 5

There are a few different ways you can achieve what you are asking for.

1.) Extend the application class and instantiate your controller and model objects there.

public class FavoriteColorsApplication extends Application {

    private static FavoriteColorsApplication application;
    private FavoriteColorsService service;

    public FavoriteColorsApplication getInstance() {
        return application;
    }

    @Override
    public void onCreate() {
        super.onCreate();
        application = this;
        application.initialize();
    }

    private void initialize() {
        service = new FavoriteColorsService();
    }

    public FavoriteColorsService getService() {
        return service;
    }

}

Then you can call the your singleton from your custom Application object at any time:

public class FavoriteColorsActivity extends Activity {

private FavoriteColorsService service = null;
private ArrayAdapter<String> adapter;
private List<String> favoriteColors = new ArrayList<String>();

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

    service = ((FavoriteColorsApplication) getApplication()).getService();
    favoriteColors = service.findAllColors();

    ListView lv = (ListView) findViewById(R.id.favoriteColorsListView);
    adapter = new ArrayAdapter<String>(this, R.layout.favorite_colors_list_item,
            favoriteColors);
    lv.setAdapter(adapter);
}

2.) You can have your controller just create a singleton instance of itself:

public class Controller {
    private static final String TAG = "Controller";
    private static sController sController;
    private Dao mDao;

    private Controller() {
        mDao = new Dao();    
    }

    public static Controller create() {
        if (sController == null) {
            sController = new Controller();
        }
        return sController;
    }
}

Then you can just call the create method from any Activity or Fragment and it will create a new controller if one doesn't already exist, otherwise it will return the preexisting controller.

3.) Finally, there is a slick framework created at Square which provides you dependency injection within Android. It is called Dagger. I won't go into how to use it here, but it is very slick if you need that sort of thing.

I hope I gave enough detail in regards to how you can do what you are hoping for.

Answer 6

Try Like This:

Create a shared data class:

SharedData.java

import android.app.Application;

/**
 * Created by kundan on 6/23/2015.
 */
public class Globals {


    private static Globals instance = new Globals();

    // Getter-Setters
    public static Globals getInstance() {
        return instance;
    }

    public static void setInstance(Globals instance) {
        Globals.instance = instance;
    }

    private String notification_index;


    private Globals() {

    }


    public String getValue() {
        return notification_index;
    }


    public void setValue(String notification_index) {
        this.notification_index = notification_index;
    }



}

Declared/Initiaze an instance of class globally in those classes where you want to set/get data (using this code before onCreate() method):-

Globals sharedData = Globals.getInstance();

Set data:

sharedData.setValue("kundan");

Get data:

String n = sharedData.getValue();

Answer 7

Use SharedPreferences to store and retrieve global variables.

SharedPreferences preferences = PreferenceManager.getDefaultSharedPreferences(this);
String userid = preferences.getString("userid", null);

Answer 8

You can create a Global Class like this:

public class GlobalClass extends Application{

    private String name;
    private String email;

    public String getName() {
        return name;
    }

    public void setName(String aName) {
        name = aName;
    }

    public String getEmail() {
        return email;
    }

    public void setEmail(String aEmail) {
        email = aEmail;
    }
}

Then define it in the manifest:

<application
    android:name="com.example.globalvariable.GlobalClass" ....

Now you can set values to global variable like this:

final GlobalClass globalVariable = (GlobalClass) getApplicationContext();
globalVariable.setName("Android Example context variable");

You can get those values like this:

final GlobalClass globalVariable = (GlobalClass) getApplicationContext();
final String name  = globalVariable.getName();

Please find complete example from this blog Global Variables

Answer 9

// My Class Global Variables  Save File Global.Java
public class Global {
    public static int myVi; 
    public static String myVs;
}

// How to used on many Activity

Global.myVi = 12;
Global.myVs = "my number";
........
........
........
int i;
int s;
i = Global.myVi;
s = Global.myVs + " is " + Global.myVi;

Answer 10

I checked for similar answer, but those given here don't fit my needs. I find something that, from my point of view, is what you're looking for. The only possible black point is a security matter (or maybe not) since I don't know about security.

I suggest using Interface (no need to use Class with constructor and so...), since you only have to create something like :

public interface ActivityClass {

    public static final String MYSTRING_1 = "STRING";

    public static final int MYINT_1 = 1;

}

Then you can access everywhere within your classes by using the following:

int myInt = ActivityClass.MYINT_1;
String myString = ActivityClass.MYSTRING_1;

Answer 11

Technically this does not answer the question, but I would recommend using the Room database instead of any global variable. https://developer.android.com/topic/libraries/architecture/room.html Even if you are 'only' needing to store a global variable and it's no big deal and what not, but using the Room database is the most elegant, native and well supported way of keeping values around the life cycle of the activity. It will help to prevent many issues, especially integrity of data. I understand that database and global variable are different but please use Room for the sake of code maintenance, app stability and data integrity.

Answer 12

If possible, you should declare the variables that you need to keep alive that haven't been clear by Garbage Collector or Unload by OS in file .so To do it, you must code by C/C++ and compile to .so lib file and load it in your MainActivity.

Answer 13

import android.app.Application;

public class Globals extends Application
{
    private static Globals instance = null;
    private static int RecentCompaignID;
    private static int EmailClick;
    private static String LoginPassword;
    static String loginMemberID;
    private static String CompaignName = "";
    private static int listget=0;
    //MailingDetails
    private static String FromEmailadd="";
    private static String FromName="";
    private static String ReplyEmailAdd="";
    private static String CompaignSubject="";
    private static int TempId=0;
    private static int ListIds=0;

    private static String HTMLContent="";
    @Override
    public void onCreate() 
    {
        super.onCreate();
        instance = this;
    }

    public static Globals getInstance()
    {
        return instance;
    }

    public void setRecentCompaignID(int objRecentCompaignID)
    {
        RecentCompaignID = objRecentCompaignID;
    }

    public int getRecentCompaignID() 
    {
        return RecentCompaignID;
    }

    public void setLoginMemberID(String objloginMemberID) 
    {
        loginMemberID = objloginMemberID;
    }

    public String getLoginMemberID() 
    {
        return loginMemberID;
    }

    public void setLoginMemberPassword(String objLoginPassword)
    {
        LoginPassword = objLoginPassword;
    }

    public String getLoginMemberPassword()
    {
        return LoginPassword;
    }

    public void setEmailclick(int id)
    {
        EmailClick = id;
    }

    public int getEmailClick() 
    {
        return EmailClick;
    }
    public void setCompaignName(String objCompaignName)
    {
        CompaignName=objCompaignName;
    }
    public String getCompaignName()
    {
        return CompaignName;
    }
    public void setlistgetvalue(int objlistget)
    {
        listget=objlistget;
    }
    public int getlistvalue()
    {
        return listget;
    }
    public void setCompaignSubject(String objCompaignSubject)
    {
         CompaignSubject=objCompaignSubject;
    }
    public String getCompaignSubject()
    {
        return CompaignSubject;
    }
    public void setHTMLContent(String objHTMLContent)
    {
        HTMLContent=objHTMLContent;
    }
    public String getHTMLContent()
    {
        return HTMLContent;
    }
    public void setListIds(int objListIds)
    {
        ListIds=objListIds;
    }
    public int getListIds()
    {
        return ListIds;
    }
    public void setReplyEmailAdd(String objReplyEmailAdd)
    {
        ReplyEmailAdd=objReplyEmailAdd;
    }
    public String getReplyEmailAdd()
    {
        return ReplyEmailAdd;
    }
    public void setFromName(String objFromName)
    {
        FromName=objFromName;
    }
    public String getFromName()
    {
        return FromName;
    }
    public void setFromEmailadd(String objFromEmailadd)
    {
        FromEmailadd=objFromEmailadd;
    }
    public String getFromEmailadd()
    {
        return FromEmailadd;
    }
}

Answer 14

Easy!!!!

Those variable you wanna access as global variable, you can declare them as static variables. And now, you can access those variables by using

classname.variablename;

public class MyProperties {
private static MyProperties mInstance= null;

static int someValueIWantToKeep;

protected MyProperties(){}

public static synchronized MyProperties getInstance(){
    if(null == mInstance){
        mInstance = new MyProperties();
    }
    return mInstance;
}

}

MyProperites.someValueIWantToKeep;

Thats It! ;)