Throwing Exceptions with throw, throws, and Creating Custom Exception Classes

Intermediate14 min read•Updated: 2026-10-22

🚨 Throwing Exceptions and Creating Custom Exception Classes

Introduction

To signal business violations (such as insufficient bank account balance or invalid course capacity), you create custom domain exceptions inheriting from Exception (checked) or RuntimeException (unchecked).

💻 Creating and Throwing a Custom Exception

1// Custom Domain Exception
2class InsufficientFundsException extends Exception {
  private double currentBalance;
  private double attemptedWithdrawal;
5 
  public InsufficientFundsException(double balance, double withdrawal) {
      super(String.format("Withdrawal of ₹%.2f exceeds balance of ₹%.2f", withdrawal, balance));
      this.currentBalance = balance;
      this.attemptedWithdrawal = withdrawal;
  }
11 
  public double getDeficit() {
      return attemptedWithdrawal - currentBalance;
  }
15}
16 
17public class BankService {
  public static void withdraw(double balance, double amount) throws InsufficientFundsException {
      if (amount > balance) {
          throw new InsufficientFundsException(balance, amount); // Explicitly throw!
      }
      System.out.printf("Successfully withdrew ₹%.2f%n", amount);
  }
24 
  public static void main(String[] args) {
      try {
          withdraw(5000.0, 7500.0);
      } catch (InsufficientFundsException e) {
          System.err.println("[FAILED TRANSACTION]: " + e.getMessage());
          System.err.printf("Shortfall amount: ₹%.2f%n", e.getDeficit());
      }
  }
33}

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Overview of java.util.Collection Hierarchy

Throwing Exceptions with throw, throws, and Creating Custom Exception Classes

Intermediate14 min read•Updated: 2026-10-22

Study Materials

🚨 Throwing Exceptions and Creating Custom Exception Classes

Introduction

💻 Creating and Throwing a Custom Exception

1// Custom Domain Exception
2class InsufficientFundsException extends Exception {
  private double currentBalance;
  private double attemptedWithdrawal;
5 
  public InsufficientFundsException(double balance, double withdrawal) {
      super(String.format("Withdrawal of ₹%.2f exceeds balance of ₹%.2f", withdrawal, balance));
      this.currentBalance = balance;
      this.attemptedWithdrawal = withdrawal;
  }
11 
  public double getDeficit() {
      return attemptedWithdrawal - currentBalance;
  }
15}
16 
17public class BankService {
  public static void withdraw(double balance, double amount) throws InsufficientFundsException {
      if (amount > balance) {
          throw new InsufficientFundsException(balance, amount); // Explicitly throw!
      }
      System.out.printf("Successfully withdrew ₹%.2f%n", amount);
  }
24 
  public static void main(String[] args) {
      try {
          withdraw(5000.0, 7500.0);
      } catch (InsufficientFundsException e) {
          System.err.println("[FAILED TRANSACTION]: " + e.getMessage());
          System.err.printf("Shortfall amount: ₹%.2f%n", e.getDeficit());
      }
  }
33}

Next Lesson

Overview of java.util.Collection Hierarchy

Continue learning with hands-on practice, examples, and exercises in the upcoming topic.

Related Lessons

Previous Lesson	Next Lesson
Automatic Resource Management: try-with-resources and AutoCloseable	Overview of java.util.Collection Hierarchy

Practice Quiz

Test your understanding of this lesson with 1 questions. Each question has one correct answer.

Previous Next