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Exception Hierarchy in Java

Java’s exception handling is based on a well-defined hierarchy. At the top of this hierarchy is the Throwable class, which has two main subclasses:

  1. Error: Represents serious problems that a program should not try to handle.
  2. Exception: Represents conditions a program might want to catch.

Exception Hierarchy Structure

                 Throwable
                /         \
           Error            Exception
           /   \            /       \
      VMError  IOError   IOException  RuntimeException
                               /                \
                      FileNotFoundException  ArithmeticException

Understanding Throwable

The Throwable class is the parent of all errors and exceptions in Java. It has two main subclasses:

Errors in Java

Errors represent system-level issues that usually cannot be recovered from. Examples include:

Example: StackOverflowError

package com.vvsk.fullstack.exceptions;

public class StackOverflowExample {
    public static void recursiveMethod() {
        recursiveMethod(); // Causes StackOverflowError
    }

    public static void main(String[] args) {
        recursiveMethod();
    }
}

Example: OutOfMemoryError

package com.vvsk.fullstack.exceptions;

import java.util.ArrayList;

public class OutOfMemoryExample {
    public static void main(String[] args) {
        ArrayList<int[]> list = new ArrayList<>();
        while (true) {
            list.add(new int[1000000]); // Causes OutOfMemoryError
        }
    }
}

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