Interview question

What is a StackOverflowError vs an OutOfMemoryError in Java? Java में StackOverflowError और OutOfMemoryError में क्या अंतर है?

Answer

Error	Cause	Common trigger
StackOverflowError	Call stack exceeds its maximum size	Infinite or excessively deep recursion
OutOfMemoryError	Heap (or other memory area) exhausted	Memory leaks, loading huge datasets, too many objects retained

// StackOverflowError example
public void recurse() {
    recurse();  // no base case - each call adds a new stack frame
}
// recurse();  // java.lang.StackOverflowError

// Fixed with a proper base case
public int factorial(int n) {
    if (n <= 1) return 1;  // base case stops the recursion
    return n * factorial(n - 1);
}

// OutOfMemoryError example - heap space exhausted
import java.util.*;
public void memoryLeak() {
    List<int[]> list = new ArrayList<>();
    while (true) {
        list.add(new int[1000000]);  // keeps allocating, never released
    }
}
// java.lang.OutOfMemoryError: Java heap space

// Both extend Error (not Exception) since they represent serious,
// often unrecoverable JVM-level problems that applications generally
// should NOT try to catch and continue from

// Both ARE technically catchable, but doing so is usually a bad idea:
try {
    recurse();
} catch (StackOverflowError e) {
    System.out.println('Caught, but the program state may be unstable now');
}

// Increasing JVM memory limits (doesn't fix underlying leaks, just delays them)
// java -Xmx512m -Xss1m MyApp   (-Xmx: heap size, -Xss: thread stack size)

Error	कारण	Common trigger
StackOverflowError	Call stack अपनी max size से बड़ा हो जाए	Infinite या बहुत गहरी recursion
OutOfMemoryError	Heap memory खत्म हो जाए	Memory leaks, बहुत बड़ा data

public void recurse() {
    recurse();  // कोई base case नहीं
}
// java.lang.StackOverflowError

public int factorial(int n) {
    if (n <= 1) return 1;  // base case recursion रोकता है
    return n * factorial(n - 1);
}

import java.util.*;
public void memoryLeak() {
    List<int[]> list = new ArrayList<>();
    while (true) {
        list.add(new int[1000000]);  // कभी release नहीं होता
    }
}
// java.lang.OutOfMemoryError: Java heap space

// दोनों Error extend करते हैं (Exception नहीं), serious JVM problems हैं

try {
    recurse();
} catch (StackOverflowError e) {
    System.out.println('Caught, पर program state अस्थिर हो सकता है');
}

// JVM memory limits बढ़ाना
// java -Xmx512m -Xss1m MyApp

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