Exception handling in java

Example:

// File Name InsufficientFundsException.java import java.io.*; public class InsufficientFundsException extends Exception { private double amount; public InsufficientFundsException(double amount) { this.amount = amount; } public double getAmount() { return amount; } }

To demonstrate using our user-defined exception, the following CheckingAccount class contains a withdraw() method that throws an InsufficientFundsException.

// File Name CheckingAccount.java import java.io.*; public class CheckingAccount { private double balance; private int number; public CheckingAccount(int number) { this.number = number; } public void deposit(double amount) { balance += amount; } public void withdraw(double amount) throws InsufficientFundsException { if(amount <= balance) { balance -= amount; } else { double needs = amount - balance; throw new InsufficientFundsException(needs); } } public double getBalance() { return balance; } public int getNumber() { return number; } }

The following BankDemo program demonstrates invoking the deposit() and withdraw() methods of CheckingAccount.

// File Name BankDemo.java public class BankDemo { public static void main(String [] args) { CheckingAccount c = new CheckingAccount(101); System.out.println("Depositing $500..."); c.deposit(500.00); try { System.out.println("\nWithdrawing $100..."); c.withdraw(100.00); System.out.println("\nWithdrawing $600..."); c.withdraw(600.00); }catch(InsufficientFundsException e) { System.out.println("Sorry, but you are short $" + e.getAmount()); e.printStackTrace(); } } }

Compile all the above three files and run BankDemo, this would produce following result:

Depositing $500... Withdrawing $100... Withdrawing $600... Sorry, but you are short $200.0 InsufficientFundsException at CheckingAccount.withdraw(CheckingAccount.java:25) at BankDemo.main(BankDemo.java:13)

Exception Example in java

public class ExcepTest{

   public static void main(String args[]){
      int a[] = new int[2];
      try{
         System.out.println("Access element three :" + a[3]);
      }catch(ArrayIndexOutOfBoundsException e){
         System.out.println("Exception thrown  :" + e);
      }
      finally{
         a[0] = 6;
         System.out.println("First element value: " +a[0]);
         System.out.println("The finally statement is executed");
      }
   }
}

Simple Thread in java

public class SimpleThread extends Thread {
  private int countDown = 5;
  private static int threadCount = 0;
  public SimpleThread() {
    super("" + ++threadCount); // Store the thread name
    start();
  }
  public String toString() {
    return "#" + getName() + ": " + countDown;
  }
  public void run() {
    while(true) {
      System.out.println(this);
      if(--countDown == 0) return;
    }
  }
  public static void main(String[] args) {
    for(int i = 0; i < 5; i++)
      new SimpleThread();
  }
}