How to create a list of global variables that can be accessible from different classes?

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Global variables in Java

How to create a list of global variables that can be accessible from different classes? Should I create a class of global variables...?

Please explain what you are trying to achieve. People might be able to provide a better answer or perhaps tell you why it's not a good idea. — Vadim, Jan 24 '12 at 11:41
Generally global state is considered a really, really bad idea. Goto is completely harmless in comparison. — Tom Hawtin - tackline, Jan 24 '12 at 12:36

score 2 · Answer 1 · answered Jan 24 '12 at 11:45

you can say

    public  class GlobalVariables{
    public static final Integer INT_VAR=12;
    public static final String STR_VAR="abcd";
//  public static final List<SomeObject> someObjectList=new ArrayList<SomeObject>()// this can be populated using some method later.
    }

you can also use interfaces and enums for declaring global variables..

Joe Axon · Answer 2 · 2012-01-24T12:02:19.080

1

Personally, I would create a class containing public static variables and then use import static MyClass.* in each class the variables are required.

import static MyClass.*;

class MainClass {
    void someMethod() {
        // using "import static" there's no need to do
        // int x = MyClass.SomeStaticInt;
        int x = SomeStaticInt;
        System.out.println(x);
    }
}

edited Jan 24 '12 at 12:02

answered Jan 24 '12 at 11:44

Joe Axon

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7

score 1 · Answer 3 · answered Jan 24 '12 at 11:46

1

Should I create a class of global variables...?

Yes. create a static class having public static final fields.

final will mark those fields as constants.

answered Jan 24 '12 at 11:46

Azodious

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score 1 · Accepted Answer · answered Jan 24 '12 at 11:47

1

you can create one class called ConstantCodes.java

Now declare your variable in this class has follows,

public class ConstantCodes
{
      public static String PublicVariable = "I am public variable"; 
}

Now you can above variable anywhere from your project using below line,

String myStr = ConstantCodes.PublicVariable;

answered Jan 24 '12 at 11:47

Lucifer

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If I don´t know apriori the values of global variables and want to define them from JTextField (SWING), then can I do something like this: ConstantCodes.PublicVariable = Integer.parse(txtBox.getText().toString()); ? – You Kuper Jan 24 '12 at 11:52
yes, you can but in the starting of the class. just store the values in db & try to retrieve from it, if no value found then display default one. got it ? – Lucifer Jan 24 '12 at 11:55

score 0 · Answer 5 · answered Jan 24 '12 at 11:40

0

Use a interface or enum for constants declaration.

answered Jan 24 '12 at 11:40

Pokuri

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How to create a list of global variables that can be accessible from different classes?

5 Answers5