This article will help you understand what a Marker or Tagged Interface in Java is. Before understanding marker interface, let’s revise on Interface. INTERFACE Similar to an object, an Interface is a blueprint of a class. It consists of static constants and abstract methods. It is a mechanism to achieve abstraction and multiple inheritance in Java. It is declared using the interface keyword. It provides total abstraction, meaning all methods in an interface must be declared with empty body, and all fields must be public, static and final by default. Syntax interface { // constant fields declaration ... Read More

No. It is not allowed in Java. Compiler will fail the compilation throwing error that the blank final field may not have been initialized.

No. It is not allowed in Java. The compiler will fail the compilation throwing error that the blank final field may not have been initialized.

this can be used to get the current object.this can be used to invoke current object's method.this() can be used to invoke current class constructorthis can be passed as a parameter to a method call.this can be passed as a parameter to a constructor.this can be used to return the current object from the method.

No. For Java based application, JVM will complain about missing main method.

Following is the required program.ExampleLive Demopublic class Tester {    public static void main(String args[]) {       //matrix 1       int a[][] = { { 1, 3, 4 }, { 2, 4, 3 }, { 3, 4, 5 } };       //matrix 2       int b[][] = { { 1, 3, 4 }, { 2, 4, 3 }, { 1, 2, 4 } };       //result matrix       int c[][] = new int[3][3]; // 3 rows and 3 columns       // subtract and print matrix       for (int i = 0; i < 3; i++) {          for (int j = 0; j < 3; j++) {             c[i][j] = a[i][j] - b[i][j];             System.out.print(c[i][j] + " ");          }          System.out.println();       }    } }Output0 0 0 0 0 0 2 2 1

ExampleFollowing is the required program.Live Demopublic class Tester {    public static int getThirdSmallest(int[] a) {       int temp;       //sort the array       for (int i = 0; i < a.length; i++) {          for (int j = i + 1; j < a.length; j++) {             if (a[i] > a[j]) {                temp = a[i];                a[i] = a[j];                a[j] = temp;             }          }       }       //return third smallest element       return a[2];    }    public static void main(String args[]) {       int a[] = { 11,10,4, 15, 16, 13, 2 };       System.out.println("Third Smallest: " +getThirdSmallest(a));    } }OutputThird smallest: 10

Following is the required program.ExampleLive Demopublic class Tester {    static int factorial(int n) {       if (n == 0)          return 1;       else          return (n * factorial(n - 1));    }    public static void main(String args[]) {       int i, fact = 1;       int number = 5;       fact = factorial(number);       System.out.println(number + "! = " + fact);    } }Output5! = 120

Following is the required program.ExampleLive Demopublic class Tester {    public static void main(String args[]) {       int i, m = 0, flag = 0;       int n = 41;// it is the number to be checked       m = n / 2;       if (n == 0 || n == 1) {          System.out.println(n + " not a prime number");       } else {          for (i = 2; i

Following is the required program.ExampleLive Demopublic class Tester {    static int n1 = 0, n2 = 1, n3 = 0;    static void fibbonacci(int count) {       if (count > 0) {          n3 = n1 + n2;          n1 = n2;          n2 = n3;          System.out.print(" " + n3);          fibbonacci(count - 1);       }    }    public static void main(String args[]) {       int count = 5;       System.out.print(n1 + " " + n2);       fibbonacci(count - 2);    } }Output0 1 1 2 3