Interview Questions and Answers for 'Bank of america india' - 3 question(s) found - Order By Newest Advanced level question usually asked in High end product companies. Have been asked in Google and Amazon (Based on 1 Feedback) Q1. Describe, in general, how java's garbage collector works ? Core Java
Ans. The Java runtime environment deletes objects when it determines that they are no longer being used. This process is known as garbage collection. The Java runtime environment supports a garbage collector that periodically frees the memory used by objects that are no longer needed. The Java garbage collector is a mark-sweep garbage collector that scans Java dynamic memory areas for objects, marking those that are referenced. After all possible paths to objects are investigated, those objects that are not marked (i.e. are not referenced) are known to be garbage and are collected. Help us improve. Please let us know the company, where you were asked this question : Like Discuss Correct / Improve  java   garbage collection   java memory management   advanced Asked in 21 Companies intermediate   frequent Try 4 Question(s) TestRelated Questions Why Char array is preferred over String for storing password? Does garbage collection guarantee that a program will not run out of memory? Let's suppose we have an to destroy objects, Design a program to implement garbage collection ? Should we override finalize method ? What are strong, soft, weak and phantom references in Java ? Can we call the garbage collector explicitly ? What does String intern() method do? Which type of memory is cleaned / recovered by garbage collection - stack or heap ? Java doesn't provide exclusive access to memory like C/C++ and other lower level languages ? What are the advantanges and disadvantages ? Very frequently asked. Usually followed by questions related to private constructor and synchronized access. Frequently asked in JPMorgan and TCS (Based on 2 feedback) Q2. Explain Singleton Design Pattern ? Design
Ans. http://www.buggybread.com/2014/03/java-design-pattern-singleton-interview.html Help us improve. Please let us know the company, where you were asked this question : Like Discuss Correct / Improve  java   design pattern   singleton   at&t   ebay  fidelity india  united healthcare india Asked in 46 Companies intermediate   frequent Related Questions Difference between Static and Singleton Class ? What is the difference between Singleton and Prototype Bean scope in Spring ? serialization and deserialization of singleton class What is the difference between these two approaches of creating singleton Class ?
//Double Checked Locking Code
public static Singleton createInstance() {
if(singleton == null){
synchronized(Singleton.class) {
if(singleton == null) {
singleton = new Singleton();
}
}
}
return singleton;
}
//Single checked locking code
public static Singleton createInstance() {
synchronized(Singleton.class) {
if(singleton == null) {
singleton = new Singleton();
}
}
return singleton;
} What are design situations to use Singleton and Prototype Design Pattern ? How to avoid cloning, serialization in the singleton class ? When singleton can break and how to resolve it If you are given choice to either load object eagerly or lazily , which one would you use in case of singleton pattern ? When should we use prototype scope and singleton scope for beans ? Q3. How to make sure that only one instance is created in Singleton Pattern ? Core Java
Ans. public class SingleTon {
private SingleTon() {
if (singleTon != null) {
throw new RuntimeException("cant not create the object");
}
}
public Object clone() throws CloneNotSupportedException {
throw new CloneNotSupportedException("can not be create");
}
static private volatile SingleTon singleTon;
public static SingleTon getInstance() {
SingleTon singleTon = this.sample;
if (singleTon == null) {
synchronized (this) {
singleTon = this.singleTon;
if (singleTon == null) {
singleTon = this.singleton = new SingleTon();
}
}
}
return singleTon;
}
} Help us improve. Please let us know the company, where you were asked this question : Like Discuss Correct / Improve  singleton  design pattern Asked in 2 Companies Related Questions Difference between Static and Singleton Class ? What is the difference between Singleton and Prototype Bean scope in Spring ? serialization and deserialization of singleton class What is the difference between these two approaches of creating singleton Class ?
//Double Checked Locking Code
public static Singleton createInstance() {
if(singleton == null){
synchronized(Singleton.class) {
if(singleton == null) {
singleton = new Singleton();
}
}
}
return singleton;
}
//Single checked locking code
public static Singleton createInstance() {
synchronized(Singleton.class) {
if(singleton == null) {
singleton = new Singleton();
}
}
return singleton;
} What are design situations to use Singleton and Prototype Design Pattern ? How to avoid cloning, serialization in the singleton class ? When singleton can break and how to resolve it If you are given choice to either load object eagerly or lazily , which one would you use in case of singleton pattern ? When should we use prototype scope and singleton scope for beans ? Explain Singleton Design Pattern ?