Type Casting in Java

Java Type Casting is the process of changing one data type into another.

This can be done in 2 ways:

  1. If the types are compatible, Java will perform the conversion implicitly (automatically). This is called Widening.
  2. If they are incompatible, then the programmer must perform explicit casting or Narrowing.

There are many Type Conversion code examples on this site if you want to learn more.

Widening

Widening is a process in which one type is automatically converted to another. 

There are two cases of widening:

  • When both types are compatible with each other,
  • When we assign a value of a smaller data type to a bigger data type.

Example:

class Test { 
 
  public static void main(String[] args) {
    short a = 10;
    
    int b = a; // automatically converts the short type into int type
    
    int c = 10;
    
    long d = c; // automatically converts the integer type into long type
    
    float f = d; // automatically converts the long type into float type
    
    System.out.println(a);
    System.out.println(b);
    System.out.println(c);
    System.out.println(d);
    System.out.println(f);
  }
}
Output: 10 10 10 10 10.0
 
In the above example, we assigned a smaller type to a larger one, and the conversation was made automatically.
 
java type casting widening


Narrowing

Converting a higher data type into a lower one is called narrowing type casting. It must be done explicitly by the programmer. Otherwise, a compiler error will occur.

Example:

class Test {
    
  public static void main(String[] args) {
    double d = 10.5;
        
    long b = (long) d; // converting double data type into long data type
    
    long l = 10;
        
    int a = (int) l; // converting long data type into integer data type
        
    System.out.println(d);
    System.out.println(b);
    System.out.println(l);
    System.out.println(a);
  }
}
Output: 10.5 10 10 10
 
In the above example, we assigned a higher data type to a lower one. We did this explicitly by specifying which type we wanted to convert the value to in parentheses.
 
java type casting narrowing


In this lesson, you learned what type casting is in Java. For more examples, check out other Conversion examples in Java

In the next tutorial, you will learn about Upcasting vs Downcasting.

Happy learning!

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