java example to throw a new exception if given condition satisfied

import java.util.Scanner;
import java.io.*;
class Employee{
public static void main(String args[]){
String name;
int age;
System.out.println("ENTER EMPLOYEE DETAILS");
System.out.println("Enter Name and Age Of The Employee:");
Scanner in=new Scanner(System.in);

try
{
if(!(in.nextLine().matches("[a-zA-Z]+"))){
throw new IOException("Please Enter The Name in Aplhabets");
}
age=in.nextInt();
if(age>50){
System.out.println("Age greater than 50 Exception");
throw new Exception("You Are Too Old to Work , Take Retirement");
}
Employee x=new Employee();
System.out.println("Object Created");
}
catch(Exception ex){
System.out.println(ex.getMessage());
}
}
}

example to throw ArithmeticException in java

import java.util.Scanner;

public class Divisor{
public static void main(String[] args){
Scanner inp=new Scanner(System.in);
System.out.println("Enter the First number");
double x=inp.nextDouble();
System.out.println("Enter the Second number");
double y=inp.nextDouble();
Divisor d= new Divisor();
d.divide(x,y);
}
public void divide(double x, double y){
double result=0;
try{
if(y==0){
throw new ArithmeticException("Divisor Cannot Be Zero");
}
}
catch(ArithmeticException ae){
System.out.println("Exception:Divisor Cannot be ZERO "+"\n Enter the Divisor again");
Scanner inp=new Scanner(System.in);
y=inp.nextDouble();
}
result=(x/y);
System.out.println("Result of the divsion is "+result);
}
}

arrays and exception example in java

import java.util.Scanner;

public class DisplayRecords {
public static void main(String[] args){
try{
System.out.println("Enter The Roll Numbers of The Students");
int []a=new int[10];
Scanner input=new Scanner(System.in);
for(int i=0;i<10;i++){
a[i]=input.nextInt();
}
System.out.println("Enter The Name Of The Students");
String []s=new String[10];
for(int i=0;i<10;i++){
s[i]=input.nextLine();
}
System.out.println("Entered Roll No for the Students");
for(int i=0;i<10;i++){
System.out.println(a[i]);
}
System.out.println("Entered Name of The Students");
for(int i=0;i<10;i++){
System.out.println(s[i]);
}
}
catch(ArrayIndexOutOfBoundsException ae){
System.out.println("Caught Exception");
}
}
}

java example to throw exception

import java.util.Scanner;

public class Collision{

public static void main(String[] args){
int x=0;
System.out.println("     ONE WAY \nDo Not Take a U Turn");
Scanner inp=new Scanner(System.in);
x=inp.nextInt();
try{
if(x>0){
throw new Exception("Please Stop Immediately In Order To Avoide Collision");
}
else{
System.out.println("Have a Safe Journey");
}
}
catch (Exception ex){
System.out.println(ex.getMessage());
}
}
}

A very simple example to show the concept of interface in java

interface Test{
public void square(int j);
}

class Arithmetic implements Test{
public void square(int j){
int result;
result=(j*j);
System.out.println("Square Of The Integer Is="+result);
}
}

public class ToTestInt{
public static void main(String[] args){
Arithmetic ar=new Arithmetic();
ar.square(12);
}
}

example of interface in java two add two integers

interface A{
public void meth1(int j, int k);
public void meth2(int x, int y, int z);
}

public class MyClass implements A{
int y,x,z;
public void meth1(int j, int k){
int result;
result=(j+k);
System.out.println("Sum Of The Integers is="+result);
}
public void meth2(int x,int y,int z) {
this.x=x;
this.y=y;
this.z=z;
System.out.println("Entered value of Integers is x="+x+" y="+y+" z="+z);
}
public static void main(String[] args){
MyClass mc=new MyClass();
mc.meth1(12,14);
mc.meth2(14,1,5);
}
}

another example of interface in java to show division

interface Test{
public void division(double x, double y);
public void calMod(double x);
}
public class DivMod{
public void division(double x,double y){
double result;
result=(x/y);
System.out.println("Result for Division is="+result);
}
public void calMod(double x){
if(x<0){
System.out.println("Modulus of |"+x+"| is");
x=-x;
System.out.println(x);
}
else{
System.out.println("Modulus of |"+x+"| is"+x);
}
}
public static void main(String[] args){
DivMod dm= new DivMod();
dm.calMod(-12);
dm.division(14,7);
}
}