Added Calculator class with basic operations

Author: Afifa637

OOPExamples/Calculator.java

@@ -0,0 +1,14 @@
+public class Calculator {
+    public int add(int a, int b) { 
+        return a + b; 
+    }
+    public int subtract(int a, int b) { 
+        return a - b; 
+    }
+    public int multiply(int a, int b) { 
+        return a * b; 
+    }
+    public int divide(int a, int b) { 
+        return b != 0 ? a / b : 0; 
+    }
+}

OOPExamples/Student.java renamed to OOPExamples/Employee.java

@@ -1,13 +1,13 @@
-public class Student {
+public class Employee {
     private String name;
     private int age;
-    private int roll;
+    private int id;
 
     //constructors
-    public Student(String name, int age, int rollNo){
+    public Employee(String name, int age, int id){
         this.name = name;
         this.age = age;
-        this.rollNo = roll;
+        this.id = id;
     }
     //getters
     public String getName(){ 
@@ -16,8 +16,8 @@ public String getName(){
     public int getAge(){ 
         return age; 
     }
-    public int getRollNo() { 
-        return roll; 
+    public int getIDNo() { 
+        return id; 
     }
     //setters
     public void setName(String name) { 
@@ -26,8 +26,8 @@ public void setName(String name) {
     public void setAge(int age) { 
         this.age = age; 
     }
-    public void setRollNo(int rollNo) { 
-        this.rollNo = roll; 
+    public void setIDNo(int id) { 
+        this.id = id; 
     }
 }