Type Casting
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In Java, every value has a specific type, and sometimes we need to convert a value from one type to another. This is called type casting.
There are two types of casting:
- Implicit casting;
- Explicit casting.
Implicit Casting
Implicit casting happens when Java automatically converts a smaller type into a larger type. This is safe because no data is lost:
int lattePrice = 5;
double priceDecimal = lattePrice; // becomes 5.0
This works because a larger type like double can easily hold everything a smaller type like int can.
Explicit Casting
Explicit casting happens when a larger type is manually converted into a smaller type. This is required because data might be lost during conversion:
double lattePrice = 4.99;
int roundedPrice = (int) lattePrice; // becomes 4
Java removes the decimal part and stores only 4. Unlike implicit casting, this must be written manually using (type).
A simple way to remember:
- small → big = automatic;
- big → small = manual.
Example
Main.java
1234567891011121314151617package com.example; public class Main { public static void main(String[] args) { int lattePrice = 5; // implicit casting double priceDecimal = lattePrice; System.out.println(priceDecimal); // 5.0 // explicit casting double realPrice = 4.99; int roundedPrice = (int) realPrice; System.out.println(roundedPrice); // 4 } }
The example first implicitly casts int to double — Java does this automatically and the result becomes 5.0. Then we explicitly cast double to int using (int), which drops the decimal and prints 4.
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