Double Datatype Example in Java

Introduction

Double Datatype is a classic Java console program that demonstrates the concept with complete source code and sample output. Java primitive types and wrappers behave differently from objects — these examples show declaration, range and conversion.

This tutorial walks through the program line by line, explains how the logic works, and highlights best practices you can apply in your own code.

Definition

Double is a keyword which designates the 64 bit float primitive type. The java.lang.Double class is the nominal wrapper class when you need to store a double value but an object reference is required.

Syntax

double  = ;

Double Datatype Example Program

class DoubleDatatype{
	public static void main(String[] args){
		double a=22.8;
		double b=100.0;
		System.out.println(""+a);
		System.out.println(""+b);
	}
}

Sample Output

22.8
100.0

When to use

Use this double datatype example when learning or revising core Java syntax.

How it works

1. Execution begins in the main method — the JVM calls this method when you run the class.

2. double a=22.8; updates a variable used in the calculation or output.

3. double b=100.0; updates a variable used in the calculation or output.

4. A println / print call writes text to the console — part of the sample output below.

5. A println / print call writes text to the console — part of the sample output below.

6. Compare your console output with the sample output for Double Datatype to confirm the program behaves correctly.

Best Practices

• Use meaningful variable and class names that describe their purpose.
• Compile and run the program locally — modify values to see how output changes.
• Read compiler errors carefully; they usually point to the exact line to fix.

Common Mistakes

• Copying code without understanding each line — practice by changing one statement at a time.
• Mismatching the public class name and the .java filename.
• Forgetting semicolons at the end of statements.