Java Data Types

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4 years ago

Data types are very important in Java because it is a strongly typed language. All operations are type-checked by the compiler for type compatibility. Strong type checking helps prevent errors. All variables, expressions, and values have a type.

Java contains two general categories of built-in data types:

Object-oriented
Primitive (non-object-oriented)

Object-oriented types are defined by classes (will be discussed later).

Primitive types are not objects in an object-oriented sense, but rather, normal binary values.

There are 8 primitive types.

Integers

Java defines four integer types which are byte, short, int, and long. All of the integer types are signed positive and negative values. Java does not support unsigned (positive-only) integers.

Type	Width in Bits	Range
byte	8	–128 to 127
short	16	–32,768 to 32,767
int	32	–2,147,483,648 to 2,147,483,647
long	64	–9,223,372,036,854,775,808 to 9,223,372,036,854,775,807

Integer types

public class RectangleSquare {
  public static void main(String[] args) {
    int a = 10;
    int b = 20;
    int c;

    c = a * b;

    System.out.println("Rectangle square is " + c);
  }
}

public class RectangleSquare {

public static void main(String[] args) {

int a = 10;

int b = 20;

int c;

c = a * b;

System.out.println("Rectangle square is " + c);

}

Floating-Point

The floating-point types represents numbers that have fractional part.

There are 2 floating types – float and double.

Type	Width in Bits	Precision
Float	32	single-precision numbers
Double	64	double-precision numbers

Floating-point types

public class FloatExample {
  public static void main(String[] args) {
    double distance;

    distance = 10.5 * 200.5;

    System.out.println("Distance is " + distance);
  }
}

public class FloatExample {

public static void main(String[] args) {

double distance;

distance = 10.5 * 200.5;

System.out.println("Distance is " + distance);

}

Characters

In Java characters use Unicode.

Type	Width in Bits	Range
Characters	Unsigned 16	0 to 65,536

Since char is an unsigned 16-bit type, character variables can be handled like integers and it is possible to perform various arithmetic manipulations on a char variable.

public class CharExample {
  public static void main(String[] args) {
    char ch = 'A';

    System.out.println("ch is " + ch);

    // Increment ch
    ch++;
    System.out.println("ch now is " + ch);
  }
}

public class CharExample {

public static void main(String[] args) {

char ch = 'A';

System.out.println("ch is " + ch);

// Increment ch

ch++;

System.out.println("ch now is " + ch);

}

The Boolean Type

The boolean type represents true/false values. Java defines the values true and false using the reserved words true and false.

public class BooleanExample {
  public static void main(String args[]) {
    boolean b;

    b = false;
    System.out.println("b is " + b);

    b = true;
    System.out.println("b is " + b);

    // a boolean value can control the if statement
    if (b) System.out.println("This is executed.");

    b = false;
    if (b) System.out.println("This is not executed.");

    // Outcome of a relational operator is a boolean value
    System.out.println("5 < 10 is " + (5 < 10));
  }
}