exception handling and basic file operations in Java

src/main/java/org/Exceptions/FileService.java

@@ -1,5 +1,11 @@
 package org.Exceptions;
 
+import java.io.BufferedReader;
+import java.io.BufferedWriter;
+import java.io.FileReader;
+import java.io.FileWriter;
+import java.io.IOException;
+import java.text.ParseException;
 import java.text.SimpleDateFormat;
 import java.util.Date;
 import java.util.Scanner;
@@ -45,35 +51,32 @@ public class FileService {
 
 
     public static String writeFile(UserEntity user) {
-        //TODO: Uncomment the lines below.
+        try {
-        //TODO: Use your knowledge of exception handling to make the code work as expected
+            FileWriter fw = new FileWriter("userInformation.txt", true);
+            BufferedWriter bw = new BufferedWriter(fw);
 
-        /* Uncomment this section
+            bw.write(user.toString());
-        //TODO: handle the exception
+            bw.close();
-        FileWriter fw = new FileWriter("userInformation.txt", true);
+        } catch (IOException e) {
-        BufferedWriter bw = new BufferedWriter(fw);
+            System.out.println("Error writing to file: " + e.getMessage());
-
+            return "failed to write user information";
-        bw.write(user.toString());
+        }
-        bw.close();
-         */
         return "user information written to file";
     }
 
 
     public static void readFile() {
-        //TODO: Uncomment the lines below.
+        try {
-        //TODO: Use your knowledge of exception handling to make the code work as expected
+            FileReader file = new FileReader("userInformation.txt");
+            BufferedReader fileInput = new BufferedReader(file);
 
-        /* Uncomment this section
+            for (int counter = 0; counter < 3; counter++)
-        FileReader file = new FileReader("userInformation.txt");
+                System.out.println(fileInput.readLine());
 
-        BufferedReader fileInput = new BufferedReader(file);
+            fileInput.close();
-
+        } catch (IOException e) {
-        for (int counter = 0; counter < 3; counter++)
+            System.out.println("Error reading file: " + e.getMessage());
-            System.out.println(fileInput.readLine());
+        }
-
-        fileInput.close();
-         */
     }
 
 
@@ -82,9 +85,11 @@ public class FileService {
 
         Date dob = null;
 
-        //TODO: Uncomment this line.
+        try {
-        //TODO: Use your knowledge of exception handling to make the code work as expected
+            dob = formatter.parse(date);
-        //dob = formatter.parse(date);
+        } catch (ParseException e) {
+            System.out.println("Error: invalid date format, expected yyyy-MM-dd - " + e.getMessage());
+        }
 
         return dob;
     }

src/main/java/org/Exceptions/RuntimeExceptionDemo.java

@@ -19,44 +19,58 @@ public class RuntimeExceptionDemo {
     //nullPointerException
     //IllegalArgumentException
     public static void validateEmail(UserEntity user) {
+        try {
+            String email = user.getEmail();
 
-        String email = user.getEmail();
+            String emailRegex = "^[A-Za-z0-9+_.-]+@[A-Za-z0-9.-]+$";
 
-        String emailRegex = "^[A-Za-z0-9+_.-]+@[A-Za-z0-9.-]+$";
+            if (!Pattern.matches(emailRegex, email)) {
+                throw new IllegalArgumentException("Invalid email format");
+            }
 
-        if (!Pattern.matches(emailRegex, email)) {
+            System.out.println("User email is valid");
-            throw new IllegalArgumentException("Invalid email format");
+        } catch (NullPointerException e) {
+            System.out.println("Error: email is null - " + e.getMessage());
+        } catch (IllegalArgumentException e) {
+            System.out.println("Error: " + e.getMessage());
         }
-
-        System.out.println("User email is valid");
     }
 
     // ArithmeticException
     public static void calculatePayment(int totalAmount, int installmentCount) {
+        try {
+            int payment = totalAmount / installmentCount;
 
-        int payment = totalAmount / installmentCount;
+            System.out.println("Each installment : " + payment);
-
+        } catch (ArithmeticException e) {
-        System.out.println("Each installment : " + payment);
+            System.out.println("Error: cannot divide by zero - " + e.getMessage());
+        }
     }
 
     // NumberFormatException
     public static void convertUserAge(String ageInput) {
+        try {
+            int age = Integer.parseInt(ageInput);
 
-        int age = Integer.parseInt(ageInput);
+            System.out.println("User age: " + age);
-
+        } catch (NumberFormatException e) {
-        System.out.println("User age: " + age);
+            System.out.println("Error: invalid number format - " + e.getMessage());
+        }
     }
 
 //    IllegalStateException
     public static void completeRegistration(UserEntity user) {
+        try {
+            if (user.getDateOfBirth() == null) {
+                throw new IllegalStateException(
+                        "Registration cannot be completed. Date of birth is missing."
+                );
+            }
 
-        if (user.getDateOfBirth() == null) {
+            System.out.println("Registration completed");
-            throw new IllegalStateException(
+        } catch (IllegalStateException e) {
-                    "Registration cannot be completed. Date of birth is missing."
+            System.out.println("Error: " + e.getMessage());
-            );
         }
-
-        System.out.println("Registration completed");
     }
 
 }