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hitanshu310 2025-12-31 19:13:50 +05:30
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21
build.gradle Normal file
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plugins {
id 'java'
}
group = 'com.hithomelabs.dsa'
version = '1.0-SNAPSHOT'
repositories {
mavenCentral()
}
dependencies {
testImplementation platform('org.junit:junit-bom:5.10.0')
compileOnly 'org.projectlombok:lombok:1.18.34'
annotationProcessor 'org.projectlombok:lombok:1.18.34'
testImplementation 'org.junit.jupiter:junit-jupiter'
}
test {
useJUnitPlatform()
}

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gradle/wrapper/gradle-wrapper.jar vendored Normal file
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6
gradle/wrapper/gradle-wrapper.properties vendored Normal file
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#Sun Aug 03 17:08:53 IST 2025
distributionBase=GRADLE_USER_HOME
distributionPath=wrapper/dists
distributionUrl=https\://services.gradle.org/distributions/gradle-8.10-bin.zip
zipStoreBase=GRADLE_USER_HOME
zipStorePath=wrapper/dists

234
gradlew vendored Executable file
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#!/bin/sh
#
# Copyright © 2015-2021 the original authors.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# https://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#
##############################################################################
#
# Gradle start up script for POSIX generated by Gradle.
#
# Important for running:
#
# (1) You need a POSIX-compliant shell to run this script. If your /bin/sh is
# noncompliant, but you have some other compliant shell such as ksh or
# bash, then to run this script, type that shell name before the whole
# command line, like:
#
# ksh Gradle
#
# Busybox and similar reduced shells will NOT work, because this script
# requires all of these POSIX shell features:
# * functions;
# * expansions «$var», «${var}», «${var:-default}», «${var+SET}»,
# «${var#prefix}», «${var%suffix}», and «$( cmd )»;
# * compound commands having a testable exit status, especially «case»;
# * various built-in commands including «command», «set», and «ulimit».
#
# Important for patching:
#
# (2) This script targets any POSIX shell, so it avoids extensions provided
# by Bash, Ksh, etc; in particular arrays are avoided.
#
# The "traditional" practice of packing multiple parameters into a
# space-separated string is a well documented source of bugs and security
# problems, so this is (mostly) avoided, by progressively accumulating
# options in "$@", and eventually passing that to Java.
#
# Where the inherited environment variables (DEFAULT_JVM_OPTS, JAVA_OPTS,
# and GRADLE_OPTS) rely on word-splitting, this is performed explicitly;
# see the in-line comments for details.
#
# There are tweaks for specific operating systems such as AIX, CygWin,
# Darwin, MinGW, and NonStop.
#
# (3) This script is generated from the Groovy template
# https://github.com/gradle/gradle/blob/master/subprojects/plugins/src/main/resources/org/gradle/api/internal/plugins/unixStartScript.txt
# within the Gradle project.
#
# You can find Gradle at https://github.com/gradle/gradle/.
#
##############################################################################
# Attempt to set APP_HOME
# Resolve links: $0 may be a link
app_path=$0
# Need this for daisy-chained symlinks.
while
APP_HOME=${app_path%"${app_path##*/}"} # leaves a trailing /; empty if no leading path
[ -h "$app_path" ]
do
ls=$( ls -ld "$app_path" )
link=${ls#*' -> '}
case $link in #(
/*) app_path=$link ;; #(
*) app_path=$APP_HOME$link ;;
esac
done
APP_HOME=$( cd "${APP_HOME:-./}" && pwd -P ) || exit
APP_NAME="Gradle"
APP_BASE_NAME=${0##*/}
# Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
DEFAULT_JVM_OPTS='"-Xmx64m" "-Xms64m"'
# Use the maximum available, or set MAX_FD != -1 to use that value.
MAX_FD=maximum
warn () {
echo "$*"
} >&2
die () {
echo
echo "$*"
echo
exit 1
} >&2
# OS specific support (must be 'true' or 'false').
cygwin=false
msys=false
darwin=false
nonstop=false
case "$( uname )" in #(
CYGWIN* ) cygwin=true ;; #(
Darwin* ) darwin=true ;; #(
MSYS* | MINGW* ) msys=true ;; #(
NONSTOP* ) nonstop=true ;;
esac
CLASSPATH=$APP_HOME/gradle/wrapper/gradle-wrapper.jar
# Determine the Java command to use to start the JVM.
if [ -n "$JAVA_HOME" ] ; then
if [ -x "$JAVA_HOME/jre/sh/java" ] ; then
# IBM's JDK on AIX uses strange locations for the executables
JAVACMD=$JAVA_HOME/jre/sh/java
else
JAVACMD=$JAVA_HOME/bin/java
fi
if [ ! -x "$JAVACMD" ] ; then
die "ERROR: JAVA_HOME is set to an invalid directory: $JAVA_HOME
Please set the JAVA_HOME variable in your environment to match the
location of your Java installation."
fi
else
JAVACMD=java
which java >/dev/null 2>&1 || die "ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
Please set the JAVA_HOME variable in your environment to match the
location of your Java installation."
fi
# Increase the maximum file descriptors if we can.
if ! "$cygwin" && ! "$darwin" && ! "$nonstop" ; then
case $MAX_FD in #(
max*)
MAX_FD=$( ulimit -H -n ) ||
warn "Could not query maximum file descriptor limit"
esac
case $MAX_FD in #(
'' | soft) :;; #(
*)
ulimit -n "$MAX_FD" ||
warn "Could not set maximum file descriptor limit to $MAX_FD"
esac
fi
# Collect all arguments for the java command, stacking in reverse order:
# * args from the command line
# * the main class name
# * -classpath
# * -D...appname settings
# * --module-path (only if needed)
# * DEFAULT_JVM_OPTS, JAVA_OPTS, and GRADLE_OPTS environment variables.
# For Cygwin or MSYS, switch paths to Windows format before running java
if "$cygwin" || "$msys" ; then
APP_HOME=$( cygpath --path --mixed "$APP_HOME" )
CLASSPATH=$( cygpath --path --mixed "$CLASSPATH" )
JAVACMD=$( cygpath --unix "$JAVACMD" )
# Now convert the arguments - kludge to limit ourselves to /bin/sh
for arg do
if
case $arg in #(
-*) false ;; # don't mess with options #(
/?*) t=${arg#/} t=/${t%%/*} # looks like a POSIX filepath
[ -e "$t" ] ;; #(
*) false ;;
esac
then
arg=$( cygpath --path --ignore --mixed "$arg" )
fi
# Roll the args list around exactly as many times as the number of
# args, so each arg winds up back in the position where it started, but
# possibly modified.
#
# NB: a `for` loop captures its iteration list before it begins, so
# changing the positional parameters here affects neither the number of
# iterations, nor the values presented in `arg`.
shift # remove old arg
set -- "$@" "$arg" # push replacement arg
done
fi
# Collect all arguments for the java command;
# * $DEFAULT_JVM_OPTS, $JAVA_OPTS, and $GRADLE_OPTS can contain fragments of
# shell script including quotes and variable substitutions, so put them in
# double quotes to make sure that they get re-expanded; and
# * put everything else in single quotes, so that it's not re-expanded.
set -- \
"-Dorg.gradle.appname=$APP_BASE_NAME" \
-classpath "$CLASSPATH" \
org.gradle.wrapper.GradleWrapperMain \
"$@"
# Use "xargs" to parse quoted args.
#
# With -n1 it outputs one arg per line, with the quotes and backslashes removed.
#
# In Bash we could simply go:
#
# readarray ARGS < <( xargs -n1 <<<"$var" ) &&
# set -- "${ARGS[@]}" "$@"
#
# but POSIX shell has neither arrays nor command substitution, so instead we
# post-process each arg (as a line of input to sed) to backslash-escape any
# character that might be a shell metacharacter, then use eval to reverse
# that process (while maintaining the separation between arguments), and wrap
# the whole thing up as a single "set" statement.
#
# This will of course break if any of these variables contains a newline or
# an unmatched quote.
#
eval "set -- $(
printf '%s\n' "$DEFAULT_JVM_OPTS $JAVA_OPTS $GRADLE_OPTS" |
xargs -n1 |
sed ' s~[^-[:alnum:]+,./:=@_]~\\&~g; ' |
tr '\n' ' '
)" '"$@"'
exec "$JAVACMD" "$@"

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gradlew.bat vendored Normal file
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@rem
@rem Copyright 2015 the original author or authors.
@rem
@rem Licensed under the Apache License, Version 2.0 (the "License");
@rem you may not use this file except in compliance with the License.
@rem You may obtain a copy of the License at
@rem
@rem https://www.apache.org/licenses/LICENSE-2.0
@rem
@rem Unless required by applicable law or agreed to in writing, software
@rem distributed under the License is distributed on an "AS IS" BASIS,
@rem WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
@rem See the License for the specific language governing permissions and
@rem limitations under the License.
@rem
@if "%DEBUG%" == "" @echo off
@rem ##########################################################################
@rem
@rem Gradle startup script for Windows
@rem
@rem ##########################################################################
@rem Set local scope for the variables with windows NT shell
if "%OS%"=="Windows_NT" setlocal
set DIRNAME=%~dp0
if "%DIRNAME%" == "" set DIRNAME=.
set APP_BASE_NAME=%~n0
set APP_HOME=%DIRNAME%
@rem Resolve any "." and ".." in APP_HOME to make it shorter.
for %%i in ("%APP_HOME%") do set APP_HOME=%%~fi
@rem Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
set DEFAULT_JVM_OPTS="-Xmx64m" "-Xms64m"
@rem Find java.exe
if defined JAVA_HOME goto findJavaFromJavaHome
set JAVA_EXE=java.exe
%JAVA_EXE% -version >NUL 2>&1
if "%ERRORLEVEL%" == "0" goto execute
echo.
echo ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
echo.
echo Please set the JAVA_HOME variable in your environment to match the
echo location of your Java installation.
goto fail
:findJavaFromJavaHome
set JAVA_HOME=%JAVA_HOME:"=%
set JAVA_EXE=%JAVA_HOME%/bin/java.exe
if exist "%JAVA_EXE%" goto execute
echo.
echo ERROR: JAVA_HOME is set to an invalid directory: %JAVA_HOME%
echo.
echo Please set the JAVA_HOME variable in your environment to match the
echo location of your Java installation.
goto fail
:execute
@rem Setup the command line
set CLASSPATH=%APP_HOME%\gradle\wrapper\gradle-wrapper.jar
@rem Execute Gradle
"%JAVA_EXE%" %DEFAULT_JVM_OPTS% %JAVA_OPTS% %GRADLE_OPTS% "-Dorg.gradle.appname=%APP_BASE_NAME%" -classpath "%CLASSPATH%" org.gradle.wrapper.GradleWrapperMain %*
:end
@rem End local scope for the variables with windows NT shell
if "%ERRORLEVEL%"=="0" goto mainEnd
:fail
rem Set variable GRADLE_EXIT_CONSOLE if you need the _script_ return code instead of
rem the _cmd.exe /c_ return code!
if not "" == "%GRADLE_EXIT_CONSOLE%" exit 1
exit /b 1
:mainEnd
if "%OS%"=="Windows_NT" endlocal
:omega

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settings.gradle Normal file
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rootProject.name = 'corejava'

106
src/main/java/com/hithomelabs/dsa/concurrency/DeadLock.java Normal file
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package com.hithomelabs.dsa.concurrency;
/*
* * Example of deadlock
*/
import lombok.AllArgsConstructor;
class Aloo{
public void alooSong(){
System.out.println("Aloo ... le lo");
}
}
class Kanda{
public void kandaSong(){
System.out.println("kandaa ... le looo");
}
}
@AllArgsConstructor
class Vendor1 implements Runnable {
Aloo aloo;
Kanda kanda;
@Override
public void run() {
System.out.println("Vendor1 singing");
synchronized (aloo) {
aloo.alooSong();
// * * sleep
try {
Thread.sleep(1000);
} catch (InterruptedException e) {
throw new RuntimeException(e);
}
synchronized (kanda) {
kanda.kandaSong();
}
}
}
}
@AllArgsConstructor
class Vendor2 implements Runnable{
Aloo aloo;
Kanda kanda;
@Override
public void run() {
System.out.println("Vendor2 singing");
synchronized (kanda){
kanda.kandaSong();
// * * sleep
try {
Thread.sleep(1000);
} catch (InterruptedException e) {
throw new RuntimeException(e);
}
synchronized (aloo){
aloo.alooSong();
}
}
}
}
public class DeadLock {
public static void main(String[] args) throws InterruptedException {
// * * Shared resources
Aloo aaloo = new Aloo();
Kanda kanda = new Kanda();
// * * Declaring the two threads, with 2 vendors
Thread t1 = new Thread(new Vendor1(aaloo, kanda));
Thread t2 = new Thread(new Vendor2(aaloo, kanda));
t1.start();
t2.start();
// * * Looking at the state the threads are in
Thread.sleep(500);
System.out.println(t1 + ":" + t1.getState());
System.out.println(t2 + ":" + t2.getState());
System.out.println("Main thread state :" + Thread.currentThread().getState());
// * * Looking at the state the threads are in
Thread.sleep(1000);
System.out.println(t1 + ":" + t1.getState());
System.out.println(t2 + ":" + t2.getState());
System.out.println("Main thread state :" + Thread.currentThread().getState());
t1.join();
t2.join();
}
}

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src/main/java/com/hithomelabs/dsa/concurrency/DeadLockExampleWithLock.java Normal file
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package com.hithomelabs.dsa.concurrency;
/*
* * An example where one vendor gets the lock but deadlock is avoided
*/
import lombok.AllArgsConstructor;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;
class Paper{
private static Lock lock = new ReentrantLock();
private String message;
public String procurePaper() {
boolean hasLock = false;
try{
if(lock.tryLock(500, TimeUnit.MILLISECONDS)){
hasLock = true;
return "writing on paper ...";
}
else{
return "Could not get lock";
}
}catch (Exception e){
System.out.println(e.getMessage());
}
finally {
if (hasLock)
lock.unlock();
}
return "";
}
}
class Pen{
private String message;
private static Lock lock = new ReentrantLock();
public String procurePen(){
boolean hasLock = false;
try{
if(lock.tryLock(500,TimeUnit.MILLISECONDS)){
hasLock = true;
Thread.sleep(5000);
return "Writing with pen ...";
}
else{
return "Could not get lock";
}
}
catch(Exception e){
System.out.println(e.getMessage());
}
finally {
if(hasLock)
lock.unlock();
}
return "";
}
}
@AllArgsConstructor
class VendorWithLock1 implements Runnable{
Pen pen;
Paper paper;
@Override
public void run() {
System.out.println(Thread.currentThread() + paper.procurePaper());
System.out.println(Thread.currentThread() + pen.procurePen());
}
}
@AllArgsConstructor
class VendorWithLock2 implements Runnable{
Pen pen;
Paper paper;
@Override
public void run() {
System.out.println(Thread.currentThread() + pen.procurePen());
System.out.println(Thread.currentThread() + paper.procurePaper());
}
}
public class DeadLockExampleWithLock {
public static void main(String[] args) throws InterruptedException {
// * * Shared resources
Pen pen = new Pen();
Paper paper = new Paper();
// * * Declaring the two threads, with 2 vendors
Thread t1 = new Thread(new VendorWithLock1(pen, paper));
Thread t2 = new Thread(new VendorWithLock2(pen, paper));
t1.start();
t2.start();
t1.join();
t2.join();
}
}

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src/main/java/com/hithomelabs/dsa/concurrency/Drop.java Normal file
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package com.hithomelabs.dsa.concurrency;
class Producer implements Runnable{
Drop drop;
Producer(Drop drop){
this.drop = drop;
}
// This is the produce method
@Override
public void run() {
for (int i = 0; i < 1000; i++) {
try {
drop.setMessage("Produced");
} catch (InterruptedException e) {
throw new RuntimeException(e);
}
}
}
}
class Consumer implements Runnable{
Drop drop;
Consumer(Drop drop){
this.drop = drop;
}
@Override
public void run() {
for (int i = 0; i < 1000; i++) {
try {
drop.consumeMessage();
} catch (InterruptedException e) {
throw new RuntimeException(e);
}
}
}
}
public class Drop {
private String message;
private boolean consumed = true;
public synchronized void setMessage(String message) throws InterruptedException {
// * * Before producer produces message it has to check, if flag is true
// * * If flag is true, it means, good to produce
while(!consumed){
this.wait();
}
System.out.println(message);
this.message = message;
// * * Notify once production is complete
consumed = false;
this.notifyAll();
}
public synchronized void consumeMessage() throws InterruptedException{
// * * Will wait to consume unless
while(consumed){
this.wait();
}
System.out.println("Consumed message");
this.message = "";
consumed = true;
this.notifyAll();
}
public static void main(String[] args){
// * * Shared object where producer drops produce and consumer consumes it
Drop drop = new Drop();
// * * providing the same drop object to both producer and consumer
Thread t1 = new Thread(new Producer(drop));
Thread t2 = new Thread(new Consumer(drop));
t2.start();
t1.start();
}
}

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src/main/java/com/hithomelabs/dsa/concurrency/InterruptExample.java Normal file
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package com.hithomelabs.dsa.concurrency;
public class InterruptExample {
public static void main(String[] args) {
Thread gaanvKaWatchman = new Thread(()->{
while(true){
try{
Thread.sleep(1000);
} catch (InterruptedException e) {
System.out.println("All is not well");
System.out.println(e);
return;
}
System.out.println("Aal izz well");
}
});
gaanvKaWatchman.start();
int counter = 5;
while(counter > 0){
try {
Thread.sleep(3000);
} catch (InterruptedException e) {
throw new RuntimeException(e);
}
System.out.println("Looks like watchman is awake !! :: Checking in " + counter);
counter--;
}
System.out.println("Let me check ! Watchman is asleep, wake him up");
gaanvKaWatchman.interrupt();
}
}

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src/main/java/com/hithomelabs/dsa/concurrency/RaceCondition.java Normal file
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package com.hithomelabs.dsa.concurrency;
/*
* * Using Threads often leads to unpredictable outputs (non-deterministic)
* * This is when two threads simultaneously execute a block of code
* * This is called a race condition and the block of code is called the critical section
*/
import lombok.Getter;
public class RaceCondition {
// * * Creating a Runnable class Counter, having a field count that is incremented by the incrementCount method
// * * The run method increments count 1000 times
@Getter
static class Counter implements Runnable{
private int counter = 0;
// * * critical section
synchronized void incrementCounter(){
this.counter++;
}
@Override
public void run() {
for(int i = 0; i < 1000; i++)
incrementCounter();
}
}
public static void main(String[] args) throws InterruptedException {
Counter counter = new Counter();
Thread t1 = new Thread(counter);
Thread t2 = new Thread(counter);
// * * both threads attempt to increments and save simultaneously
t1.start();
t2.start();
t1.join();
t2.join();
System.out.println(counter.getCounter());
}
}

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src/main/java/com/hithomelabs/dsa/concurrency/StaticMethods.java Normal file
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package com.hithomelabs.dsa.concurrency;
import java.util.Arrays;
public class StaticMethods {
public static void main(String[] args) throws InterruptedException {
// * * we are going to look at important static methods of Threads
// * * sleep - Important thread life cycle method - passes control to other threads who want to execute
System.out.println("Sleeping for 1 second");
Thread.sleep(1000);
// * * Group 1 - Thread detail methods
System.out.println("Details of current thread: " + Thread.currentThread());
// * * Creating a runnable that sleeps fpr 5 and will use it to spawn some threads
Runnable sleepFor5 = () -> {
try {
System.out.println("Spawned new thread");
Thread.sleep(5000);
System.out.println("Slept for 5 seconds");
} catch (InterruptedException e) {
throw new RuntimeException(e);
}
};
// * * Spawning some new threads
new Thread(sleepFor5).start();
new Thread(sleepFor5).start();
new Thread(sleepFor5).start();
Thread[] array = new Thread[4];
// * * Enumerating threads
Thread.enumerate(array);
System.out.println("Enumerating all known threads");
Arrays.stream(array).forEach(t -> {
System.out.println(t);
System.out.println(t.getState());
});
System.out.println("Thread active count: " + Thread.activeCount());
System.out.println("Will wait for other threads to join me");
Arrays.stream(array).filter(thread -> !thread.equals(Thread.currentThread())).forEach(thread -> {
try {
thread.join(); // * * Not a static method but a thread life cycle method
} catch (InterruptedException e) {
throw new RuntimeException(e);
}
});
System.out.println("All threads are finished");
}
}

38
src/main/java/com/hithomelabs/dsa/concurrency/ThreadSample.java Normal file
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package com.hithomelabs.dsa.concurrency;
public class ThreadSample extends Thread {
@Override public void run(){
System.out.println("Hello this is called from: " + this.getClass());
System.out.println(Thread.currentThread());
}
public static void main(String[] args) {
/*
* * There are two ways to implement a thread, one is to extend the Thread class
* * Another one is to implement the Runnable Interface
*/
ThreadSample thread = new ThreadSample();
// * * Thread.run() doesn't start a new thread; just calls the method
thread.run();
// * * Thread.start() starts a new thread
thread.start();
// * * Now attempting with Runnable:
new Thread(new Runnable() {
@Override
public void run() {
System.out.println("Hello this is called from: " + this.getClass());
System.out.println(Thread.currentThread());
}
}).start();
// * * Can also be done using lamda expressions
new Thread(() -> System.out.println("Running from a lamda expression")).start();
}
}

52
src/main/java/com/hithomelabs/dsa/concurrency/Volatile.java Normal file
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package com.hithomelabs.dsa.concurrency;
import lombok.AllArgsConstructor;
import lombok.Setter;
@Setter
class Flag{
boolean print = true;
}
@AllArgsConstructor
class PrintLoop implements Runnable{
Flag flag;
@Override
public void run() {
int counter = 0;
while(flag.print){
System.out.println(++counter);
}
}
}
@AllArgsConstructor
class FlagFalse implements Runnable{
Flag flag;
@Override
public void run() {
try {
Thread.sleep(1000);
} catch (InterruptedException e) {
throw new RuntimeException(e);
}
flag.setPrint(false);
}
}
public class Volatile {
public static void main(String[] args) {
Flag flag = new Flag();
new Thread(new PrintLoop(flag)).start();
new Thread(new FlagFalse(flag)).start();
}
}