Android global variable dynamic value

Question

Hello all i want to make use of a global integer variable that i shall be incrementing in 7 different activities according to the users right or wrong choise. The problem is that i every time i implement the variable in each different activity , the value is not kept. Instead i get the default value of the variable. What i want is that every increment i make to the variable is saved , when i use it again in the next variable. Any help appreciated. I have tried and failed :

public class MyApplication extends Application {

private int grade=0;

public int setGrade(int grade) {
    this.grade = grade;
}

public int getGrade() {
    return grade;
}

}

public class lessonOnePhoto extends Activity {

private int grade = ((MyApplication) this.getApplication()).getGrade();

if (rbtn[0].getText().toString().equals("Boy")) {
grade++;
}
else {
Toast.makeText(getApplicationContext(),"Wrong Choise",Toast.LENGHT_SHORT).show();
}
}

score 2 · Accepted Answer · answered Apr 28 '15 at 08:04

The grade you are incrementing is local and private to your activity. It is also a primitive, rather than an object, so grade = .getGrade() will set the local variable to the same value as the global value, it is not some kind of reference.

Instead, do something like this:

MyApplication myApplication = ((MyApplication) this.getApplication());
myApplication.setGrade(myApplication.getGrade()++);

Or implement increment decrement methods.

public class MyApplication extends Application {

private int grade=0;

public int setGrade(int grade) {
    this.grade = grade;
}

public int getGrade() {
    return grade;
}

public void incrementGrade() {
    grade++;
}

public void decrementGrade() {
    grade--;
}

score 0 · Answer 2 · answered Apr 28 '15 at 08:04

0

you have to increment the original application value .. not the copy to maintain the variable in between the activities

if (rbtn[0].getText().toString().equals("Boy")) {
grade++;
}

change to

if (rbtn[0].getText().toString().equals("Boy")) {
((MyApplication) this.getApplication()).setGrade(grade++)
}

answered Apr 28 '15 at 08:04

Dinesh Kannan

1,255
13
32

This won't work. If grade is changed somewhere else, the activity will not have the current value. – Simon Apr 28 '15 at 08:07

Deniz · Answer 3 · 2015-04-28T08:09:37.703

0

You can add one method in application class to increment value

public class MyApplication extends Application {

private int grade=0;

public int incrementGrade() {
    this.grade = grade + 1;
}

public int setGrade(int grade) {
    this.grade = grade;
}

public int getGrade() {
    return grade;
}
}

and increment when needed

MyApplication myApplication = ((MyApplication) this.getApplication());
myApplication.incrementGrade();

OR ================

Make that grade static and increment by accessing it in static way

 public static int grade = 0;

access it lie this

 MyApplication.grade ++;

edited Apr 28 '15 at 08:09

answered Apr 28 '15 at 08:05

Deniz

12,332
10
44
62

It's bad practice to make variables public. Instead, use getters and setters so that in the future, if the implementation of grade in the application changes (e.g. to shared preferences or a database) the rest of the code does not need to change. – Simon Apr 28 '15 at 08:09

score 0 · Answer 4 · edited May 23 '17 at 11:58

0

You can get the result from the activities where the user enters the response and handle it from a MainActivity that manages all the responses.

Another option to avoid storing information in the Application class could be to have a Singleton with a Shared Instance that stores the global variables. However, the use of singletons is considered a bad practice in some cases.

edited May 23 '17 at 11:58

Community

1
1

answered Apr 28 '15 at 08:06

AlexGuti

3,063
1
27
28

Android global variable dynamic value

4 Answers4