In Java, is it possible to define a constant using only the final keyword?

A constant variable is a variable whose value is fixed and only one copy exists in the program. Once you declare a constant variable and assign a value to it, you cannot change its value again throughout the program.

Unlike other languages, Java does not directly support constants. However, you can still create a constant by declaring a variable as static and final.

static - Once you declare a static variable, they will be loaded into memory at compile time, i.e. only one copy will be available.

Final - Once you declare a final variable, its value cannot be modified.

So, you can create a constant in Java by declaring the instance variable as static and final.

Example

Demonstration

class Data {
   static final int integerConstant = 20;
}
public class ConstantsExample {
   public static void main(String args[]) {
      System.out.println("value of integerConstant: "+Data.integerConstant);
   }
}

Output

value of integerConstant: 20
value of stringConstant: hello
value of floatConstant: 1654.22
value of characterConstant: C

Constant without static keyword

If you create a constant without static keyword A final variable, although its value is unmodifiable, is created every time a new object is created. A separate copy of the variable is created.

Example

For example, consider the following Java program:

Online Demo

class Data {
   final int integerConstant = 20;
}
public class ConstantExample {
   public static void main(String args[]) {
      Data obj1 = new Data();
      System.out.println("value of integerConstant: "+obj1.integerConstant);
      Data obj2 = new Data();
      System.out.println("value of integerConstant: "+obj2.integerConstant);
   }
}

Output

value of integerConstant: 20
value of integerConstant: 20

Here, we create a final variable and try to print its value using both objects, although the value of the variable is the same in both instances, since we are using a different object for each instance, they are copies of the actual variable.

According to the definition of constant, you need to have only one copy of the variable in the entire program (class).

So, to create a constant as defined, you need to declare it as static and final.

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