Default Value of Data Types in Java :

Live Example : Default value of Data Type

Sample Program that will illustrate Default Value Stored in Each Primitive Data Type Variable

public class DefaultValue {
  static boolean bool;
  static byte by;
  static char ch;
  static double d;
  static float f;
  static int i;
  static long l;
  static short sh;
  static String str;
  public static void main(String[] args) {
    System.out.println("Bool :" + bool);
    System.out.println("Byte :" + by);
    System.out.println("Character:" + ch);
    System.out.println("Double :" + d);
    System.out.println("Float :" + f);
    System.out.println("Integer :" + i);
    System.out.println("Long :" + l);
    System.out.println("Short :" + sh);
    System.out.println("String :" + str);
  }
}

Output :

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Bool     :false
Byte     :0
Character:
Double   :0.0
Float    :0.0
Integer  :0
Long     :0
Short    :0
String   :null

boolean Data Type : Primitive Data Type in Java Programming

1. Boolean is primitive data type in Java.
2. Boolean data type is used for logical values.
3. Boolean data type can have two possible values : true or false.
4. Boolean is the type returned by all relational operators
5. Boolean is the type required by the conditional expressions used in control statements such as if and for.
6. “Boolean” is wrapper class for “boolean” primitive data type.

How to Declare & Display Boolean Variable ?

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public static void main(String args[]) {
 boolean b1,b2,b3;
 b1 = true;  // Assigning Value
 b2 = false; // Assigning Value
 b3 = b2;    // Assigning Variable
 System.out.println(b1); // Printing Value
 System.out.println(b2); // Printing Value
 System.out.println(b3); // Printing Value
}

Output :

true
false
false

Live Example :

// Demonstrate boolean values.
class BoolTest {
  public static void main(String args[]) {
    boolean b1;
    b1 = false;
    System.out.println("b1 is " + b1);
    b1 = true;
    System.out.println("b1 is " + b1);
  // a boolean value can control the if statement
    if(b1) System.out.println("This is executed.");
    b = false;
    if(b)
      System.out.println("Not executed.");
 // outcome of relational operator is a boolean
    System.out.println("100 > 90 is " + (100 > 90));
  }
}

Output :

b1 is false
b1 is true
This is executed.
100 > 90 is true

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Different Ways of Using Boolean Value :

Way 1 : Inside If Statement

public static void main(String args[])
{
 boolean b;
 b = true;
 if(b)
   {
   System.out.println("I am True");
   }
}

• Boolean Value is used to check whether condition is true or not.
• No need to do == to check equality

public static void main(String args[])
{
 boolean b;
 b = true;
 if(b == true)
   {
   System.out.println("I am True");
   }
}

Way 2 : Comparing Two Numbers

class Demo {
public static void main(String args[]) {
 boolean b;
 b = (10 > 6);
 if(b)
   {
   System.out.println("10 > 6");
   }
 }
}

we can use boolean value to hold the result Comparison operators. here 10 > 6 therefor true will be stored in boolean variable

Character data Type : Java Primitive Data Types

1. In Java, the data type used to store characters is char.
2. Character is 16 bits wide in Java.
3. Java uses Unicode to represent characters.
4. Java support lot of Unicode symbols from many more human languages for this purpose, it requires 16 bits.
5. The range of a char is 0 to 65,536.
6. There are no negative chars.

What is Unicode ?

Unicode defines a fully international character set that can represent all of the characters found in all human languages.

Live Example 1 : Integer Value Assigned to Character Data Type

class CharDemo {
  public static void main(String args[]) {
    char ch;
    ch = 'M';
    System.out.println("Character is : " + ch);
  }
}

Output :

Character is : M

Live Example 2 : Integer Value Assigned to Character Data Type

// Demonstrate char data type.
class CharDemo {
  public static void main(String args[]) {
    char ch1, ch2;
    ch1 = 88; // code for X
    ch2 = 'Y';
    System.out.print("ch1 and ch2: ");
    System.out.println(ch1 + "" + ch2);
  }
}

Output :

ch1 and ch2: X Y

Live Example 3 : Incrementing Character Variable

class CharDemo2 {
  public static void main(String args[]) {
    char ch1;
    ch1 = 'P';
    System.out.println("ch1 contains " + ch1);
    ch1++; // increment ch1
    System.out.println("ch1 is now " + ch1);
  }
}

Output :

ch1 contains P
ch1 is now Q

Other Data Types in Java : Integer | Float | Character | Boolean

Integer Data Type :

1. Integer Data Type is used to store integer value.
2. Integer Data Type is Primitive Data Type in Java Programming Language.
3. Integer Data Type have respective Wrapper Class - “Integer“.
4. Integer Data Type is able to store both unsigned ans signed integer values so Java opted signed,unsigned concept of C/C++.

Integer Data Type Can have 4 types of Values these are listed below table -

Live Example : Declaring Integer Variable in Java Programming

Class IntDemo
{
public static void main(String args[])
  {
  int number=0;
  System.out.println("Total Number : " + number);
  }
}

Explanation :

1. Primitive Variable can be declared using “int” keyword.
2. Though Integer contain default Initial Value as 0 , still we have assign 0 to show assignment in Java.
3. “+” operator is used to concatenate 2 strings.
4. Integer is converted into String internally and then two strings are concatenated.

Integer Literal in Java :

1. Value Stored in the Integer Variable is called as Literal.
2. In the above example 0 is integer literal.

Primitive Data Types in Java Programming Language :

Data type is nothing but the type of the data. Each Variable in Java must have certain type associated with it which tells us what kind of data a variable can store.

Data Types in Java Programming Language are classified into two main groups - Primitive and Reference Data Types.

A primitive Data Types are :

1. Data types are predefined by the Java language.
2. Predefined data types are Reserved keyword so we cannot use them as variable name inside program/application
3. Primitive values do not share state with other primitive values.
4. Total Number of Primitive Data Types in Java Programming is 8
5. All Primitive Data Types have respective Wrapper Classes i.e Integer is wrapper class for primitive type int

Primitive Data Types are -

Classification of Data Types in Java Programming Language

Data Type and Other Details