Blog Archives

01: jvisualvm tutorial to sample Java heap memory

Java does not have a sizeof operator like C++ does. Java uses automatic memory management known as the Garbage Collection, hence it is not that important to evaluate size of various objects. But, for the purpose of learning & fixing any potential memory issues, I have used “jvisualvm”, … Read...

02: jvisualvm to detect memory leak – a quick tutorial style Java demo

This is a companion post to 8 Java Memory Management Interview Q&A demonstrating a memory leak scenario step by step with jvisualvm, which is a free profiling tool that gets shipped with JDK. Step 1: Code that causes memory leak Here is a sample code that causes memory leak. …...

10: 8 Java Maps & Caching Data in Java Interview Q&As

Q1. What is the purpose of a Map interface in Java collection API? A1. A map is a set of associations between pairs of objects. One is known as a “key” and the other is known as a “value”. It is used very frequently in programming in case where for...

6 Key considerations in processing large files in Java

Q1. What are the key considerations in processing large files?
A1. Before jumping into coding, get the requirements.

#1 Trade-offs among CPU, Memory Usage & Disk I/O

Processing a file involves reading from the disk, processing (e.g. parsing an XML and transforming), and writing back to the disk.

Read more ›

8 Java memory management interview Q&As

Q1. Are memory leaks possible in Java, which has memory management via automatic Garbage Collection? A1. Memory and resource leaks are possible in any robust application. In managed languages such as Java and C#, the developers do not have to worry too much about memory management as the garbage collector...

9 Java Garbage Collection interview questions & answers

Java Garbage Collection interview questions & answers to ascertain your depth of Java knowledge in building industry strength Java applications. Determining optimal Garbage Collection (GC) settings is critical to achieve high throughput & low latency. Q1. In which part of memory does Java Garbage Collection (i.e. … Read more ›...

Java String & Array limitations and OutOfMemoryError

Q1. What is the maximum possible length of a Java String & how much heap space do you need to store the maximum possible String object?
A1. A Java String internally uses a char array (i.e. char[]) and the indices of an array is an integer.

Read more ›

javap, jps, jmap, and jvisualvm tutorial – analyzing the heap histogram

Q1. Is there anything wrong with the code snippet shown below?

A1. The above code creates too many “Integer” objects due to auto boxing.

Q2. How do you know that the above auto unboxing and boxing code were executed?

Read more ›

Monitoring/Profiling Java applications interview Q&A

Q1 How will you go about monitoring your Java application for potential performance or memory issues? A1 1. Visual VM for monitoring Java memory, CPU, threads, etc VisualVM is a visual tool integrating several command-line JDK tools and lightweight profiling capabilities. Designed for both production and development time use, …...

800+ Java Q&As & tutorials