int and double

Learn numeric variables with int and double.

int and double

Java has two main types for numbers: int and double.

int holds 32-bit integers: between -2 billion and +2 billion. It does not allow decimals.

double holds 64-bit decimal numbers. The dot (.) separates the decimal part: 3.14.

int age = 25;
double height = 1.78;

Which one you pick depends on the value: int for whole numbers, double for decimals.

double decimals

double holds numbers with a fractional part. The dot is the decimal separator. Scientific notation is supported: 1.5e3 = 1500.0.

double pi = 3.14;
double distance = 1.5e3;
System.out.println(pi);

Dividing two doubles gives a decimal result: 7.0 / 2.0 = 3.5. But 7 / 2 (int division) = 3.

Avoid using double for money; rounding errors may occur. BigDecimal is safer for that.

Exercise Define int and double and print them

Write a Main class with a main method. Assign 30 to int age and 1.75 to double height. Print both with println.

Show example solution

public class Main {
    public static void main(String[] args) {
        int age = 30;
        double height = 1.75;
        System.out.println(age);
        System.out.println(height);
    }
}

Test yourself

Which is an int value?
- 42
- 3.14
- "number"
- true
Show answer

42 — 42 is an integer and is written as an int.
Assign a value to an int variable
```
int age = ____;
```
Show answer
```
int age = 25;
```
Match the types

int

Integer
double

Decimal
42

Int literal
3.14

Double literal

Next lesson: boolean

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