Data types in Java

1.3

There are majorly two types of languages. First one is Statically typed language where each variable and expression type is already known at compile time.Once a variable is declared to be of a certain data type, it cannot hold values of other data types.Example: C,C++, Java. Other, Dynamically typed languages: These languages can receive different data types over the time. Ruby, Python

Java is statically typed and also a strongly typed language because in Java, each type of data (such as integer, character, hexadecimal, packed decimal, and so forth) is predefined as part of the programming language and all constants or variables defined for a given program must be described with one of the data types.

Java has two categories of data:

  • Primitive data (e.g., number, character)
  • Object data (programmer created types)
  • Primitive data

    Primitive data are only single values; they have no special capabilities. There are 8 primitive data types
    primitive data types in java

    boolean
    boolean data type represents only one bit of information either true or false . Values of type boolean are not converted implicitly or explicitly (with casts) to any other type. But the programmer can easily write conversion code.

    // A Java program to demonstrate boolean data type
    class GeeksforGeeks
    {
        public static void main(String args[]) 
        {
            boolean b = true;       
            if (b == true)
                System.out.println("Hi Geek");
        }    
    }
    

    Output:

    Hi Geek
    

    byte
    The byte data type is an 8-bit signed two’s complement integer.The byte data type is useful for saving memory in large arrays.

    • Size: 8-bit
    • Value: -128 to 127
    // Java program to demonstrate byte data type in Java
    class GeeksforGeeks
    {
        public static void main(String args[]) 
        {
            byte a = 126;
    
            // byte is 8 bit value
            System.out.println(a);
           
            a++;
            System.out.println(a);
            
            // It overflows here because
            // byte can hold values from -128 to 127
            a++;
            System.out.println(a);
            
            // Looping back within the range
            a++;
            System.out.println(a);
        }    
    }

    Output:

    126
    127
    -128
    -127
    

    short
    The short data type is a 16-bit signed two’s complement integer. Similar to byte, use a short to save memory in large arrays, in situations where the memory savings actually matters.

    • Size: 16 bit
    • Value: -32,768 to 32,767 (inclusive)

    int
    It is a 32-bit signed two’s complement integer.

    • Size: 32 bit
    • Value: -231 to 231-1

    Note: In Java SE 8 and later, we can use the int data type to represent an unsigned 32-bit integer, which has value in range [0, 232-1]. Use the Integer class to use int data type as an unsigned integer.

    long:
    The long data type is a 64-bit two’s complement integer.

    • Size: 64 bit
    • Value: -263 to 263-1.

    Note: In Java SE 8 and later, you can use the long data type to represent an unsigned 64-bit long, which has a minimum value of 0 and a maximum value of 264-1. The Long class also contains methods like compareUnsigned, divideUnsigned etc to support arithmetic operations for unsigned long.

    Floating point Numbers : float and double
    float
    The float data type is a single-precision 32-bit IEEE 754 floating point. Use a float (instead of double) if you need to save memory in large arrays of floating point numbers.

    • Size: 32 bits
    • Suffix : F/f Example: 9.8f

    double:
    The double data type is a double-precision 64-bit IEEE 754 floating point. For decimal values, this data type is generally the default choice.

    Note: Both float and double data types were designed especially for scientific calculations, where approximation errors are acceptable. If accuracy is the most prior concern then, it is recommended not to use these data types and use BigDecimal class instead.
    Please see this for details: Rounding off errors in Java
    char
    The char data type is a single 16-bit Unicode character. A char is a single character.

    • Value: ‘\u0000’ (or 0) to ‘\uffff’ 65535
    // Java program to demonstrate primitive data types in Java
    class GeeksforGeeks
    {
        public static void main(String args[]) 
        {
            // declaring character
             char a = 'G';
             
            // Integer data type is generally 
            // used for numeric values
            int i=89;
            
            // use byte and short if memory is a constraint 
            byte b = 4;
            
            // this will give error as number is 
            // larger than byte range
            // byte b1 = 7888888955;
            
            short s = 56;
            
            // this will give error as number is 
            // larger than short range
            // short s1 = 87878787878;
            
            
            // by default fraction value is double in java
            double d = 4.355453532;
            
            // for float use 'f' as suffix
            float f = 4.7333434f;
           
            System.out.println("char: " + a); 
            System.out.println("integer: " + i); 
            System.out.println("byte: " + b); 
            System.out.println("short: " + s); 
            System.out.println("float: " + f); 
            System.out.println("double: " + d); 
        }    
    }

    Output:

    char: G
    integer: 89
    byte: 4
    short: 56
    float: 4.7333436
    double: 4.355453532
    

    Quiz on Data Type in Java

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