Java Data Types (Primitive)

Java Data Types

As the name suggests, data types specify the type of data that can be stored inside variables in Java.

Java is a statically-typed language. This means that all variables must be declared before they can be used.

int speed;

Here, speed is a variable, and the data type of the variable is int.

The int data type determines that the speed variable can only contain integers.

There are 8 data types predefined in Java, known as primitive data types.

Note: In addition to primitive data types, there are also referenced types (object type).

8 Primitive Data Types

1. boolean type

• The boolean data type has two possible values, either true or false.
• Default value: false.
• They are usually used for true/false conditions.

Example 1: Java boolean data type

class Main {
  public static void main(String[] args) {
    	
    boolean flag = true;
    System.out.println(flag);    // prints true
  }
}

2. byte type

• The byte data type can have values from -128 to 127 (8-bit signed two's complement integer).
• If it's certain that the value of a variable will be within -128 to 127, then it is used instead of int to save memory.
• Default value: 0

Example 2: Java byte data type

class Main {
  public static void main(String[] args) {

    byte range;
    range = 124;
    System.out.println(range);    // prints 124
  }
}

3. short type

• The short data type in Java can have values from -32768 to 32767 (16-bit signed two's complement integer).
• If it's certain that the value of a variable will be within -32768 and 32767, then it is used instead of other integer data types (int, long).
• Default value: 0

Example 3: Java short data type

class Main {
  public static void main(String[] args) {
    	
    short temperature;
    temperature = -200;
    System.out.println(temperature);  // prints -200
  }
}

4. int type

• The int data type can have values from -2³¹ to 2³¹-1 (32-bit signed two's complement integer).
• If you are using Java 8 or later, you can use an unsigned 32-bit integer. This will have a minimum value of 0 and a maximum value of 2³²-1. To learn more, visit How to use the unsigned integer in java 8?
• Default value: 0

Example 4: Java int data type

class Main {
  public static void main(String[] args) {
    	
    int range = -4250000;
    System.out.println(range);  // print -4250000
  }
}

5. long type

• The long data type can have values from -2⁶³ to 2⁶³-1 (64-bit signed two's complement integer).
• If you are using Java 8 or later, you can use an unsigned 64-bit integer with a minimum value of 0 and a maximum value of 2⁶⁴-1.
• Default value: 0

Example 5: Java long data type

class LongExample {
  public static void main(String[] args) {
    	
    long range = -42332200000L;
    System.out.println(range);    // prints -42332200000
  }
}

Notice, the use of L at the end of -42332200000. This represents that it's an integer of the long type.

6. double type

• The double data type is a double-precision 64-bit floating-point.
• It should never be used for precise values such as currency.
• Default value: 0.0 (0.0d)

Example 6: Java double data type

class Main {
  public static void main(String[] args) {
    	
    double number = -42.3;
    System.out.println(number);  // prints -42.3
  }
}

7. float type

• The float data type is a single-precision 32-bit floating-point. Learn more about single-precision and double-precision floating-point if you are interested.
• It should never be used for precise values such as currency.
• Default value: 0.0 (0.0f)

Example 7: Java float data type

class Main {
  public static void main(String[] args) {
    	
    float number = -42.3f;
    System.out.println(number);  // prints -42.3
  }
}

Notice that we have used -42.3f instead of -42.3in the above program. It's because -42.3 is a double literal.

To tell the compiler to treat -42.3 as float rather than double, you need to use f or F.

If you want to know about single-precision and double-precision, visit Java single-precision and double-precision floating-point.

8. char type

• It's a 16-bit Unicode character.
• The minimum value of the char data type is '\u0000' (0) and the maximum value of the is '\uffff'.
• Default value: '\u0000'

Example 8: Java char data type

class Main {
  public static void main(String[] args) {
    	
    char letter = '\u0051';
    System.out.println(letter);  // prints Q
  }
}

Here, the Unicode value of Q is \u0051. Hence, we get Q as the output.

Here is another example:

class Main {
  public static void main(String[] args) {
    	
    char letter1 = '9';
    System.out.println(letter1);  // prints 9
    	
    char letter2 = 65;
    System.out.println(letter2);  // prints A

  }
}

Here, we have assigned 9 as a character (specified by single quotes) to the letter1 variable. However, the letter2 variable is assigned 65 as an integer number (no single quotes).

Hence, A is printed to the output. It is because Java treats characters as an integer and the ASCII value of A is 65. To learn more about ASCII, visit What is ASCII Code?.

String type

Java also provides support for character strings via java.lang.String class. Strings in Java are not primitive types. Instead, they are objects. For example,

String myString = "Java Programming";

Here, myString is an object of the String class. To learn more, visit Java Strings.