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How to implement constants in java?
A constant variable is the one whose value is fixed and only one copy of it exists in the program. Once you declare a constant variable and assign value to it, you cannot change its value again throughout the program.
You can create a constant in c language using the constant keyword (one way to create it) as −
const int intererConstant = 100; or, const float floatConstant = 16.254; ….. etc
Constants in java
Unlike in C language constants are not supported in Java(directly). But, you can still create a constant by declaring a variable static and final.
Static − Once you declare a variable static they will be loaded in to the memory at the compile time i.e. only one copy of them is available.
Final − once you declare a variable final you cannot modify its value again.
Therefore, you can create a constant in Java by declaring the instance variable static and final.
Example
In the following Java example, we have 5 constants (static and final variables) in a class (named Data) and, accessing them from the main method of another class.
class Data{
static final int integerConstant = 20;
static final String stringConstant = "hello";
static final float floatConstant = 1654.22f;
static final char characterConstant = 'C';
}
public class ConstantsExample {
public static void main(String args[]) {
System.out.println("value of integerConstant: "+Data.integerConstant);
System.out.println("value of stringConstant: "+Data.stringConstant);
System.out.println("value of floatConstant: "+Data.floatConstant);
System.out.println("value of characterConstant: "+Data.characterConstant);
}
}Output
value of integerConstant: 20 value of stringConstant: hello value of floatConstant: 1654.22 value of characterConstant: C
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