Being Code Expert: Keywords in Java Part -2

Keywords or reserved words are those which are basically used for internal processes. We cannot create a variable name as reserved keywords.

Below are some of the reserved keywords in java.

byte: A data type that can hold 8-bit data values.

Example

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

        byte varibale = 8;

        System.out.println(varibale);
    }
}

case: It is used in switch statements to mark blocks of code. The case is used to label each branch in a switch statement.

Example

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

        String day = "Monday";
        switch (day) {
        case "Monday":
            System.out.println("Today is Monday");
            break;
        case "Tuesday":
            System.out.println("Today is Tuesday");
            break;
        case "Wednesday":
            System.out.println("Today is Wednesday");
            break;
        case "Thursday":
            System.out.println("Today is Thursday");
            break;
        case "Friday":
            System.out.println("Today is Friday");
            break;
        case "Saturday":
            System.out.println("Today is Saturday");
            break;
        case "Sunday":
            System.out.println("Today is Sunday");
            break;
        default:
            System.out.println("Not a day of week");
            break;
        }
    }
}

catch: It is used to catch the exception generated by try statements. The catch the statement allows you to define a block of code to be executed if an error occurs in the try block

Example

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

        String str = "Hello";
        try {
            System.out.println(str.charAt(10));
        } catch (IndexOutOfBoundsException e) {
            // TODO: handle exception
        } catch (Exception e) {
            // TODO: handle exception
        }

    }
}

char: A data type that can hold unsigned 16-bit Unicode characters

Example

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

        char ch = 'a';

        System.out.println(ch);
    }
}

if: Tests a true/false expression and branches accordingly. In other words, if a statement specifies a block of Java code to be executed if a condition is true.

Example

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

        int i = 2;
        if (i < 5) {
            System.out.println("Hello Java");
        }
    }
}

implements: It specifies that a class implements an interface.

Create an interface

public interface MyClass {

    void display();
}

Example

public class MyClassImp implements MyClass {

    @Override
    public void display() {
        System.out.println("Implementing the 
                        method define in interface");

    }
}

import: References other classes. The import keyword is used to import a package, class, or interface.

Example

import java.util.ArrayList;
import java.util.List;

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

        List<String> list = new ArrayList<String>();

        list.add("Hello");
        System.out.println(list);
    }
}

instanceof: It indicates whether an object is an instance of a specific class or implements an interface. The instanceof keyword compares the instance with type. The return value is either true or false.

Example

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

        MyClass myObj = new MyClass();
        System.out.println(myObj instanceof MyClass);
    }
}