Java Primitive and Non-primitive Data Types

Introduction

Data types in Java are divided into two types that are used to define variables include:

1. Primitive data types
2. Non-primitive (or reference) data types.

Sketch

The following sketch helps you understand how everything is divided based on its type.

Primitive data types

In Java, most of the work is done by primitives. These primitive data types are the foundation of all other types.

• They are used to store simple values such as numbers and characters.
• They are stored directly in memory and are accessed faster than non-primitive data types.

There are eight primitive data types in Java:  byte, short, int, long, float, double, char and boolean.

The size and range of values that can be stored in a primitive data type depending on the type itself. For example, a boolean can only hold the values true or false, while a long can hold values from -2⁶³ to 2⁶³-1.

Hence, the 8 primitive data types in Java are categorized into 4 types.

1. Integer types - byte, short, int, and long.
2. Floating point types - float and double.
3. Character type - char.
4. Boolean type - boolean.

Table

Let us see the bytes size, default value, min and max and ranges of all the primitive data types.

Integer types - (byte, short, int, and long)

There are 4 data types, that store numeric data in programs. They are:

byte:

A byte is an 8-bit signed integer.

• Occupies 1 byte.
• The default value is 0.
• It can store a min value of -2^7 or -128 and a maximum value of (2^7 - 1) or 127.

public class ByteType {
    public static void main(String[] args) {
        byte A = -1;
        byte B = 20;
        byte C = 3;

        byte add = (byte) (B + C);
        byte subtract = (byte) (B - C);

        System.out.println(add); // 23
        System.out.println(subtract); // 17
    }
}

The maximum and minimum values of byte can be found at:

byte high = Byte.MAX_VALUE;   // high == 127
byte low = Byte.MIN_VALUE;    // low == -128

short:

A short is a 16-bit signed integer.

• Occupies 2 bytes.
• The default value is 0.
• It can store a min value of -2^15 or -32768 and a maximum value of (2^15 - 1) or 32767.

public class ShortType {
    public static void main(String[] args) {
        short A = -48;
        short B = 987;
        short C = 17;

        short add = (short) (B + C);
        short subtract = (short) (B - C);

        System.out.println(add); // 1004
        System.out.println(subtract); // 970
    }
}

The maximum and minimum values of short can be found at:

short high = Short.MAX_VALUE; // high == 32767
short low = Short.MIN_VALUE;  // low = -32768

int:

This is one of Java's most used data types, storing 4 bytes of data. According to Java API, the Integer class wraps a value of the primitive type int in an object.

An int is a 32-bit signed integer.

• Occupies 4 bytes.
• The default value is 0.
• It can store a min value of -2^31 or -2B and a maximum value of (2^31 - 1) or 2B.

public class IntType {
    public static void main(String[] args) {
        int A = -48;
        int B = 987;
        int C = 17;

        int add = B + C;
        int subtract = B - C;

        System.out.println(add); // 1004
        System.out.println(subtract); // 970
    }
}

The maximum and minimum values of short can be found at:

int max = Integer.MAX_VALUE; // -2147483648
int min = Integer.MIN_VALUE; // 2147483647

long:

By default, long is a signed integer (In Java 8, it can be either signed/unsigned).

Signed: It can store a minimum of 2^63 and a maximum of (2^63 - 1).

Unsigned: It can store a minimum value of 0 and a maximum value of (2^64 - 1).

• Occupies 8 bytes.
• The default value is 0L.

If you assign long A = 100, Java assumes it as a int type. Appending L makes it a long.

public class LongType {
  public static void main(String[] args) {
    long A = -42;
    long B = 284;
    long C = 73;
    long bigNumber = 549755813888L;

    long addedLongs = B + C; // 284 + 73 = 357
    long subtractedLongs = B - C; // 284 - 73 = 211

    System.out.println(addedLongs); // 357
    System.out.println(subtractedLongs); // 211
  }
}

The maximum and minimum values of long can be found at:

// Max and Min
long high = Long.MAX_VALUE; // high == 9223372036854775807L
long low = Long.MIN_VALUE;  // low == -9223372036854775808L

Note: Letter L appended at the end of the long literal is case insensitive, however it is good practice to use capital as it is easier to distinct from digit one.

2L == 2l // true

Floating types - (float, double)

float:

A float is a single-precision 32-bit floating point number.

• Occupies 4 bytes.
• The default value is `0.0F`.
• It can store a min value of -2^149 and a maximum value of 2^127.

By default, decimals are interpreted as doubles. To create a float, append an f to the decimal literal.

A float is precise to roughly an error of 1 in 10 million.

Float.POSITIVE_INFINITY
Float.NEGATIVE_INFINITY
Float.NaN

NaN stands for the results of an operation that cannot be determined. Such as dividing two infinite values.

public class FloatType {
  public static void main(String[] args) {
    float f1 = 0f;
    float f2 = -0f;
    System.out.println(f1 == f2); // true
    System.out.println(1f / f1); // Infinity
    System.out.println(1f / f2); // -Infinity
    System.out.println(Float.POSITIVE_INFINITY / Float.POSITIVE_INFINITY); // NaN
  }
}

0f and -0f are different but == yields true.

public class FloatType {
  public static void main(String[] args) {
    // addition
    float add = 37.2f + -2.6f; // result: 34.6
    System.out.println(add);

    // subtraction
    float subtract = 45.1f - 10.3f; // result: 34.8
    System.out.println(subtract);

    // multiplication
    float multiply = 26.3f * 1.7f; // result: 44.71
    System.out.println(multiply);

    // division
    float division = 37.1f / 4.8f; // result: 7.729166
    System.out.println(division);

    // modulus
    float modulus = 37.1f % 4.8f; // result: 3.4999971
    System.out.println(modulus);


  }
}

double:

A double is a double-precision 64-bit floating point number.

• Occupies 8 bytes.
• The default value is `0.0D`.
• It can store a min value of -2^1074 and a maximum value of 2^1023.

public class DoubleType {
  public static void main(String[] args) {
    double d1 = 0d;
    double d2 = -0d;
    System.out.println(d1 == d2); // true  
    System.out.println(1d / d1); // Infinity  
    System.out.println(1d / d2); // -Infinity 
    System.out.println(Double.POSITIVE_INFINITY / Double.POSITIVE_INFINITY); // NaN
  }
}

public class DoubleType {
  public static void main(String[] args) {
    double A = -7162.37;
    double B = 974.21;
    double C = 658.7;

    double addedDoubles = B + C; // 315.51 
    double subtractedDoubles = B - C; // 1632.91

    double scientificNotationDouble = 1.2e-3; // 0.0012
  }
}

Character type - (char)

char:

A char can store a single 16-bit Unicode character. A character literal is enclosed in single quotes.

• Occupies 2 bytes.
• The default value is 0.
• It can store a minimum value of \u0000 ( 0 in the decimal representation, also called the null character) and the maximum of \uffff or (2^16 - 1).
• The char values are A, B, a, d, etc.

public class CharType {
  public static void main(String[] args) {
    char myChar = 'u'; // 'u'
    char myChar2 = '5'; // '5'
    char myChar3 = 65; // 'A'
  }
}

Boolean type - (boolean)

boolean:

A boolean can store one of two values, either true or false.

• Occupies 1 bytes.
• The default value is false.
• There is no min or max for boolean data type.

public class BooleanType {
  public static void main(String[] args) {
    boolean a = true; // true
    boolean b = false; // false
    
    boolean notA = !a; // false
    boolean notB = !b; // true
    
    boolean aAndB = a && b; // false
    boolean aOrB = a || b; // true
    
    boolean aXorB =a ^ b; // true
  }
}

Non-primitive data types

Non-primitive data types are also known as reference types or object types, and they are used to define variables that hold complex data structures such as objects and arrays.

Non-primitive data types do not store the actual value of the variable but instead, store a reference to the memory location where the data is stored.

Some examples of non-primitive data types in Java include:

1. Class: represents a class type, which is a blueprint for creating objects that share common attributes and methods.
2. Interface: represents an interface type, which defines a set of methods that a class must implement.
3. Array: represents a collection of elements of the same data type, which are stored in contiguous memory locations.
4. String: represents a sequence of characters, which can be treated as a single data type.

Non-primitive data types are created using class or interface definitions, and they can contain methods, constructors, and instance variables that define the behavior and properties of the data. They can also be passed by reference, meaning that when they are passed as arguments to a method or assigned to a variable, a reference to the memory location of the data is passed/assigned, and any changes made to the data affect the original value.