How to create a memory leak in Java

Question

I'm beginner and wanted to know about how to create a memory leak in Java?

Answer 1

Hello @kartik,

A simple thing to do is to use a HashSet with an incorrect (or non-existent) hashCode() or equals(), and then keep adding "duplicates". Instead of ignoring duplicates as it should, the set will only ever grow and you won't be able to remove them.

If you want these bad keys/elements to hang around you can use a static field like

class BadKey {
   // no hashCode or equals();
   public final String key;
   public BadKey(String key) { this.key = key; }
}

Map map = System.getProperties();
map.put(new BadKey("key"), "value"); // Memory leak even if your threads die

Hope it helps!!

Thank You!!