JavaType Casting

Java Type Casting

Type casting means converting one data type into another. For example, turning anint into adouble.

In Java, there are two main types of casting:

• Widening Casting (automatic) - converting a smaller type to a larger type size
  byte ->short ->char ->int ->long ->float ->double
  
  
• Narrowing Casting (manual) - converting a larger type to a smaller type size
  double ->float ->long ->int ->char ->short ->byte

Widening Casting

Widening casting is done automatically when passing a smaller size type into a larger size type.

This works because there is no risk of losing information. For example, anint value can safely fit inside adouble:

int myInt = 9;double myDouble = myInt; // Automatic casting: int to doubleSystem.out.println(myInt);    // Outputs 9System.out.println(myDouble); // Outputs 9.0

Narrowing Casting

Narrowing casting must be done manually by placing the type in parentheses() in front of the value.

This is required because narrowing may result in data loss (for example, dropping decimals when converting adouble to anint):

double myDouble = 9.78d;int myInt = (int) myDouble; // Manual casting: double to intSystem.out.println(myDouble); // Outputs 9.78System.out.println(myInt);    // Outputs 9

Real-Life Example

Here is a real-life example of type casting. We calculate the percentage of a user's score in relation to the maximum score in a game.

We use type casting to make sure that the result is afloating-point value, rather than an integer:

// Set the maximum possible score in the game to 500int maxScore = 500;// The actual score of the userint userScore = 423;/* Calculate the percentage of the user's score in relation to the maximum available score.Convert userScore to double to make sure that the division is accurate */double percentage = (double) userScore / maxScore * 100.0d;System.out.println("User's percentage is " + percentage);

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