Java Topics
HubJava Collections FrameworkCollections Practice ProgramsComparable vs ComparatorGenericsIteratorArrayListLinkedListStackVectorHashMapHashtableLinkedHashMapTreeMapArrayDequeDeque Double-Ended QueuePriorityQueueHashSetLinkedHashSetTreeSetAdapter PatternBuilder PatternFactory PatternMVC PatternObserver PatternSingleton PatternDynamic ProgrammingGraphHashingHeapLinked List DSAQueue DSARecursionSearching AlgorithmsSorting AlgorithmsStack DSATime ComplexityTreesException Handling Best PracticesCustom ExceptionException Hierarchyfinally BlockException Handlingthrow aur throwstry-catchBuffered StreamsByte StreamsCharacter StreamsDeserializationFile ClassJava NIO New I/OSerializationArrays in JavaArray OperationsArray Practice ProgramsArray Interview QuestionsJagged ArrayMulti-Dimensional ArraysOne Dimensional Arraybreak aur continuedo-while Loopfor Loopif-else StatementsNested Loopsswitch-case Statementwhile LoopJava Compilation ProcessJava ki FeaturesPehla Java ProgramHistory of JavaJava EditionsJava Program StructureJDK, JRE aur JVMJava Kya Hai?Immutable StringsString Class in JavaString Interview QuestionsString MethodsString Practice ProgramsStringBufferStringBuilderComments in JavaData Types in JavaIdentifiers in JavaInput & Output in JavaJava KeywordsOperators in JavaType Casting in JavaVariables in JavaJava Coding Interview QuestionsCollections Interview QuestionsCore Java Interview QuestionsJDBC Interview QuestionsMultithreading Interview QuestionsOOPs Interview QuestionsSpring Framework Interview QuestionsJava 8 Date/Time APIDefault aur Static Methods in InterfaceFunctional InterfaceLambda ExpressionMethod ReferenceOptional ClassStream APIBatch ProcessingCallableStatementJDBC ArchitectureJDBC — Java Database ConnectivityJDBC Practice ProjectsMySQL ConnectionPreparedStatementResultSetStatement InterfaceTransaction ManagementCreating ThreadsDaemon ThreadExecutor FrameworkInter-Thread CommunicationMultithreading Practice ProgramsRunnable InterfaceSynchronizationThread ClassMultithreading IntroductionThread Life CycleThread PriorityJava Cheat SheetImportant Formulas & Key ConceptsImportant Java ProgramsJava Quick RevisionAbstract ClassAbstractionAnonymous ClassClass and ObjectConstructorEncapsulationInheritanceInner ClassInterfaceMethod OverloadingMethod OverridingObject ClassObject CloningObject-Oriented Programming OOPPolymorphismstatic Keywordsuper Keywordthis KeywordWrapper ClassesArray Practice ProgramsBasic Java Practice ProgramsCollection Practice ProgramsJDBC Practice ProgramsMultithreading Practice ProgramsOOPs Practice ProgramsPlacement Coding QuestionsString Practice ProgramsBanking SystemChat ApplicationE-Commerce Backend — Spring Boot REST APIEmployee Management SystemLibrary Management SystemSpring Boot Fullstack ProjectStudent Management SystemCookies in ServletExpression Language ELGenericServletHttpServletJavaServer Pages JSPJSP TagsMVC ArchitectureHttpServletRequest & HttpServletResponseServlet IntroductionServlet Life CycleSession TrackingDependency InjectionSpring BeansSpring CoreSpring FrameworkAPI GatewaySpring Cloud Config ServerDocker DeploymentEureka Server — Service DiscoverySpring Boot CRUD ApplicationException Handling in Spring BootJWT AuthenticationREST API in Spring BootSpring SecuritySpring BootSpring Data JPAValidation in Spring Boot
Synchronization
Last Updated : 26 May, 2026
title: Synchronization in Java
Multithreading52 words6 headingsExamples included
title: Synchronization in Java description: Thread synchronization aur race conditions
Multiple threads shared data access karein to race condition aati hai. Synchronization se ek time par ek hi thread access kare.
Race Condition Example
class Counter {
int count = 0;
void increment() { count++; } // NOT thread-safe!
// count++ = read + add + write (3 operations, not atomic)
}
Counter c = new Counter();
Thread t1 = new Thread(() -> { for(int i=0; i<1000; i++) c.increment(); });
Thread t2 = new Thread(() -> { for(int i=0; i<1000; i++) c.increment(); });
t1.start(); t2.start();
t1.join(); t2.join();
System.out.println(c.count); // Should be 2000, but might be less!
synchronized Method
class Counter {
int count = 0;
synchronized void increment() {
count++; // Only one thread at a time
}
synchronized int getCount() { return count; }
}
synchronized Block (Better — fine-grained)
class Counter {
int count = 0;
private final Object lock = new Object();
void increment() {
synchronized (lock) {
count++;
}
// Other non-critical code here runs concurrently
}
}
Static synchronized
Class-level lock.
java exampleWoHoTech
class Logger {
static synchronized void log(String msg) {
System.out.println(Thread.currentThread().getName() + ": " + msg);
}
}ReentrantLock (More control)
import java.util.concurrent.locks.*;
class Counter {
int count = 0;
ReentrantLock lock = new ReentrantLock();
void increment() {
lock.lock();
try {
count++;
} finally {
lock.unlock(); // Always in finally!
}
}
}
Deadlock
java exampleWoHoTech
// Thread 1 holds lock A, waits for B
// Thread 2 holds lock B, waits for A → DEADLOCK!
// Avoid: Always acquire locks in same orderExam Focus
Revise definitions, diagrams, examples, and short-answer points for Synchronization.
Interview Use
Prepare one clear explanation, one practical example, and one common mistake for this Java topic.
Search Terms
java, java programming, core java, java master course, java notes, master, course, multithreading
Related Java Topics
Continue learning this concept
MultithreadingCreating Threadstitle: Creating Threads in JavaMultithreadingDaemon Threadtitle: Daemon Thread in JavaMultithreadingExecutor Frameworktitle: Executor Framework in JavaMultithreadingInter-Thread Communicationtitle: Inter-Thread CommunicationMultithreadingMultithreading Practice Programstitle: Multithreading ProgramsMultithreadingRunnable Interfacetitle: Runnable Interface in Java