Garbage collection overview in Java - Cheat Sheet & Quick Revision

overview

Recall & Review

beginner

What is garbage collection in Java?

Garbage collection is the process where Java automatically finds and removes objects that are no longer used to free up memory.

beginner

Why is garbage collection important?

It helps prevent memory leaks by cleaning unused objects, so the program runs smoothly without running out of memory.

beginner

What does the term 'heap' mean in Java memory management?

Heap is the part of memory where Java stores objects created during program execution. Garbage collection works mainly on the heap.

intermediate

Name one common garbage collection algorithm used in Java.

One common algorithm is the Mark-and-Sweep algorithm, which marks reachable objects and removes the rest.

intermediate

How does Java know which objects to collect?

Java tracks object references. If no active part of the program can reach an object, it is considered garbage and eligible for collection.

What does Java's garbage collector do?

A Removes objects no longer in use to free memory

B Compiles Java code into bytecode

C Manages user input and output

D Optimizes CPU usage

Where does Java store objects that garbage collection manages?

A Stack memory

B Register memory

C Cache memory

D Heap memory

Which of these is a sign that an object is ready for garbage collection?

A It has no references pointing to it

B It is still referenced by active code

C It is a primitive data type

D It is stored on the stack

Which algorithm is commonly used by Java garbage collectors?

A Binary search

B Bubble sort

C Mark-and-Sweep

D Quick sort

What problem does garbage collection help prevent?

A Syntax errors

B Memory leaks

C Slow internet

D Incorrect output

Explain in simple terms how Java's garbage collection works.

Why is garbage collection important for Java programs?