Merge remote-tracking branch 'origin/main'

# Conflicts:
#	.gitignore

.gitignore

@@ -2,7 +2,7 @@
 out/
 !**/src/main/**/out/
 !**/src/test/**/out/
-
+target/
 ### Eclipse ###
 .apt_generated
 .classpath
@@ -27,7 +27,5 @@ bin/
 
 ### Mac OS ###
 .DS_Store
-/.idea/
+.idea/
-
+*.iml
-
-/target/

.idea/.gitignore

@@ -1,3 +0,0 @@
-# Default ignored files
-/shelf/
-/workspace.xml

.idea/compiler.xml

@@ -1,14 +0,0 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<project version="4">
-  <component name="CompilerConfiguration">
-    <annotationProcessing>
-      <profile name="Maven default annotation processors profile" enabled="true">
-        <sourceOutputDir name="target/generated-sources/annotations" />
-        <sourceTestOutputDir name="target/generated-test-sources/test-annotations" />
-        <outputRelativeToContentRoot value="true" />
-        <module name="java_test" />
-      </profile>
-    </annotationProcessing>
-    <bytecodeTargetLevel target="21" />
-  </component>
-</project>

.idea/inspectionProfiles/Project_Default.xml

@@ -1,8 +0,0 @@
-<component name="InspectionProjectProfileManager">
-  <profile version="1.0">
-    <option name="myName" value="Project Default" />
-    <inspection_tool class="AutoCloseableResource" enabled="true" level="WARNING" enabled_by_default="true">
-      <option name="METHOD_MATCHER_CONFIG" value="java.util.Formatter,format,java.io.Writer,append,com.google.common.base.Preconditions,checkNotNull,org.hibernate.Session,close,java.io.PrintWriter,printf,java.io.PrintStream,printf,java.lang.foreign.Arena,ofAuto,java.lang.foreign.Arena,global,java.util.concurrent.Executors,newFixedThreadPool" />
-    </inspection_tool>
-  </profile>
-</component>

.idea/jarRepositories.xml

@@ -1,20 +0,0 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<project version="4">
-  <component name="RemoteRepositoriesConfiguration">
-    <remote-repository>
-      <option name="id" value="central" />
-      <option name="name" value="Maven Central repository" />
-      <option name="url" value="https://repo1.maven.org/maven2" />
-    </remote-repository>
-    <remote-repository>
-      <option name="id" value="jboss.community" />
-      <option name="name" value="JBoss Community repository" />
-      <option name="url" value="https://repository.jboss.org/nexus/content/repositories/public/" />
-    </remote-repository>
-    <remote-repository>
-      <option name="id" value="central" />
-      <option name="name" value="Central Repository" />
-      <option name="url" value="https://maven.aliyun.com/repository/central" />
-    </remote-repository>
-  </component>
-</project>

.idea/misc.xml

@@ -1,14 +0,0 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<project version="4">
-  <component name="ExternalStorageConfigurationManager" enabled="true" />
-  <component name="MavenProjectsManager">
-    <option name="originalFiles">
-      <list>
-        <option value="$PROJECT_DIR$/pom.xml" />
-      </list>
-    </option>
-  </component>
-  <component name="ProjectRootManager" version="2" languageLevel="JDK_21" default="true" project-jdk-name="21" project-jdk-type="JavaSDK">
-    <output url="file://$PROJECT_DIR$/out" />
-  </component>
-</project>

.idea/modules.xml

@@ -1,8 +0,0 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<project version="4">
-  <component name="ProjectModuleManager">
-    <modules>
-      <module fileurl="file://$PROJECT_DIR$/java_test.iml" filepath="$PROJECT_DIR$/java_test.iml" />
-    </modules>
-  </component>
-</project>

.idea/vcs.xml

@@ -1,6 +0,0 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<project version="4">
-  <component name="VcsDirectoryMappings">
-    <mapping directory="$PROJECT_DIR$" vcs="Git" />
-  </component>
-</project>

java_test.iml

@@ -1,8 +0,0 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<module type="JAVA_MODULE" version="4">
-  <component name="AdditionalModuleElements">
-    <content url="file://$MODULE_DIR$" dumb="true">
-      <sourceFolder url="file://$MODULE_DIR$/src" isTestSource="false" />
-    </content>
-  </component>
-</module>

src/main/java/jvm/Calculation.java

@@ -0,0 +1,68 @@
+package jvm;
+import java.lang.System; // Import System for nanoTime and printf
+
+/**
+ * A Java class to replicate the calculation performed by the Python script.
+ */
+public class Calculation {
+
+    /**
+     * Performs the iterative calculation.
+     *
+     * @param iterations The number of iterations for the loop.
+     * @param param1     The first parameter used in the calculation.
+     * @param param2     The second parameter used in the calculation.
+     * @return The result of the calculation.
+     */
+    public static double calculate(int iterations, int param1, int param2) {
+        // Initialize the result as a double
+        double result = 1.0;
+
+        // Loop from 1 to iterations (inclusive)
+        for (int i = 1; i <= iterations; i++) {
+            // Calculate the first value of j
+            // Use double for j to ensure floating-point arithmetic
+            double jMinus = (double)i * param1 - param2;
+            // Subtract 1.0 / jMinus from the result (use 1.0 for double division)
+            result -= (1.0 / jMinus);
+
+            // Calculate the second value of j
+            double jPlus = (double)i * param1 + param2;
+            // Add 1.0 / jPlus to the result
+            result += (1.0 / jPlus);
+        }
+        // Return the final calculated result
+        return result;
+    }
+
+    /**
+     * The main entry point of the program.
+     *
+     * @param args Command line arguments (not used).
+     */
+    public static void main(String[] args) {
+        // Define the parameters for the calculation
+        final int ITERATIONS = 100_000_000; // Use underscore for readability (Java 7+)
+        final int PARAM1 = 4;
+        final int PARAM2 = 1;
+
+        // Record the start time using System.nanoTime() for higher precision
+        long startTime = System.nanoTime();
+
+        // Perform the calculation and multiply the result by 4.0
+        double finalResult = calculate(ITERATIONS, PARAM1, PARAM2) * 4.0;
+
+        // Record the end time
+        long endTime = System.nanoTime();
+
+        // Calculate the duration in nanoseconds
+        long durationNanos = endTime - startTime;
+        // Convert the duration to seconds (as a double)
+        double durationSeconds = durationNanos / 1_000_000_000.0;
+
+        // Print the final result, formatted to 12 decimal places
+        System.out.printf("Result: %.12f%n", finalResult);
+        // Print the execution time, formatted to 6 decimal places
+        System.out.printf("Execution Time: %.6f seconds%n", durationSeconds);
+    }
+}

src/main/java/jvm/Calculation2.java

@@ -0,0 +1,166 @@
+package jvm;
+import java.lang.System; // Import System for nanoTime and printf
+import java.util.ArrayList;
+import java.util.List;
+import java.util.concurrent.Callable;
+import java.util.concurrent.ExecutionException;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.concurrent.Future;
+
+/**
+ * A Java class to replicate the calculation performed by the Python script,
+ * optimized using multithreading.
+ */
+public class Calculation2 {
+
+    /**
+     * Represents a task that calculates a partial sum for a given range of iterations.
+     * Implements Callable so it can be executed by an ExecutorService and return a result.
+     */
+    private static class PartialCalculator implements Callable<Double> {
+        private final int startIteration;
+        private final int endIteration;
+        private final int param1;
+        private final int param2;
+
+        /**
+         * Constructor for the partial calculator task.
+         * @param startIteration The starting iteration (inclusive).
+         * @param endIteration The ending iteration (exclusive).
+         * @param param1 The first parameter for calculation.
+         * @param param2 The second parameter for calculation.
+         */
+        public PartialCalculator(int startIteration, int endIteration, int param1, int param2) {
+            this.startIteration = startIteration;
+            this.endIteration = endIteration;
+            this.param1 = param1;
+            this.param2 = param2;
+        }
+
+        /**
+         * The computation performed by this task. Calculates the sum for the assigned range.
+         * @return The partial sum for the range.
+         */
+        @Override
+        public Double call() {
+            double partialSum = 0.0;
+            // Loop through the assigned range of iterations
+            // Note: loop goes up to < endIteration
+            for (int i = startIteration; i < endIteration; i++) {
+                // Calculate the first value of j
+                double jMinus = (double)i * param1 - param2;
+                // Subtract 1.0 / jMinus from the partial sum
+                partialSum -= (1.0 / jMinus);
+
+                // Calculate the second value of j
+                double jPlus = (double)i * param1 + param2;
+                // Add 1.0 / jPlus to the partial sum
+                partialSum += (1.0 / jPlus);
+            }
+            return partialSum;
+        }
+    }
+
+    /**
+     * Performs the iterative calculation using multiple threads.
+     *
+     * @param iterations The total number of iterations for the loop.
+     * @param param1     The first parameter used in the calculation.
+     * @param param2     The second parameter used in the calculation.
+     * @param numThreads The number of threads to use for the calculation.
+     * @return The result of the calculation.
+     * @throws InterruptedException If thread execution is interrupted.
+     * @throws ExecutionException If computation threw an exception.
+     */
+    public static double calculateParallel(int iterations, int param1, int param2, int numThreads)
+            throws InterruptedException, ExecutionException {
+
+        // Create a fixed-size thread pool
+        ExecutorService executor = Executors.newFixedThreadPool(numThreads);
+        // List to hold the Future objects representing the results of each task
+        List<Future<Double>> futureResults = new ArrayList<>();
+
+        // Calculate the approximate number of iterations per thread
+        int iterationsPerThread = iterations / numThreads;
+        int start = 1; // Start iteration from 1
+
+        // Divide the work and submit tasks to the executor
+        for (int i = 0; i < numThreads; i++) {
+            int end = start + iterationsPerThread;
+            // For the last thread, ensure it covers all remaining iterations
+            if (i == numThreads - 1) {
+                end = iterations + 1; // Go up to iterations (inclusive)
+            }
+            // Ensure end doesn't exceed the total iterations + 1 boundary
+            if (end > iterations + 1) {
+                end = iterations + 1;
+            }
+
+            // Create and submit the task for the calculated range
+            // The loop inside PartialCalculator runs from start (inclusive) to end (exclusive)
+            Callable<Double> task = new PartialCalculator(start, end, param1, param2);
+            futureResults.add(executor.submit(task));
+
+            // Set the start for the next chunk
+            start = end;
+        }
+
+        // Initialize the total result (starting from the base 1.0)
+        double totalResult = 1.0;
+        // Retrieve results from each Future and add to the total result
+        for (Future<Double> future : futureResults) {
+            // future.get() blocks until the result is available
+            totalResult += future.get();
+        }
+
+        // Shut down the executor service gracefully
+        executor.shutdown();
+
+        // Return the final combined result
+        return totalResult;
+    }
+
+    /**
+     * The main entry point of the program.
+     *
+     * @param args Command line arguments (not used).
+     */
+    public static void main(String[] args) {
+        // Define the parameters for the calculation
+        final int ITERATIONS = 100_000_000;
+        final int PARAM1 = 4;
+        final int PARAM2 = 1;
+        // Determine the number of threads based on available processors
+        final int NUM_THREADS = Runtime.getRuntime().availableProcessors();
+
+        System.out.println("Using " + NUM_THREADS + " threads.");
+
+        // Record the start time
+        long startTime = System.nanoTime();
+
+        double finalResult = 0;
+        try {
+            // Perform the parallel calculation and multiply the result by 4.0
+            finalResult = calculateParallel(ITERATIONS, PARAM1, PARAM2, NUM_THREADS) * 4.0;
+
+            // Record the end time
+            long endTime = System.nanoTime();
+
+            // Calculate the duration
+            long durationNanos = endTime - startTime;
+            double durationSeconds = durationNanos / 1_000_000_000.0;
+
+            // Print the final result and execution time
+            System.out.printf("Result: %.12f%n", finalResult);
+            System.out.printf("Execution Time: %.6f seconds%n", durationSeconds);
+
+        } catch (InterruptedException | ExecutionException e) {
+            // Handle potential exceptions during parallel execution
+            System.err.println("Calculation failed: " + e.getMessage());
+            e.printStackTrace();
+            // Ensure System.exit is not used in production code without careful consideration
+            // System.exit(1);
+        }
+    }
+}

src/main/java/jvm/SpeedTest.java

@@ -0,0 +1,36 @@
+package jvm;
+
+/**
+ * it converts from python code
+ * just check performance differences between python and java
+ */
+public class SpeedTest {
+
+    public double calculate(int iter, int param1, int param2) {
+        double result = 1.0;
+
+        for (int i = 1; i <= iter; i++) {
+            double jMinus = (double)i * param1 - param2;
+            // Subtract 1.0 / jMinus from the result (use 1.0 for double division)
+            result -= (1.0 / jMinus);
+
+            // Calculate the second value of j
+            double jPlus = (double)i * param1 + param2;
+            // Add 1.0 / jPlus to the result
+            result += (1.0 / jPlus);
+        }
+
+        return result;
+    }
+
+    public static void main(String[] args) {
+        SpeedTest speedTest = new SpeedTest();
+        long start = System.nanoTime();
+        double result = speedTest.calculate(100_000_000, 4, 1) * 4.0;
+        System.out.println(result);
+        long end = System.nanoTime();
+        long durationNanos = end - start;
+        double durationSeconds = durationNanos / 1_000_000_000.0;
+        System.out.println( durationSeconds );
+    }
+}

src/main/java/jvm/TryCatchDemo.java

@@ -0,0 +1,27 @@
+package main.java.jvm;
+
+/**
+ * in test method, x will assign to return value, here should be 1 (it will not throw any errors)
+ * then, the finally block will change x to 3, but the return value will not change
+ * How finally work is attach the code block in it to try block and catch block
+ */
+public class TryCatchDemo {
+
+    public int test() {
+        int x=0;
+        try {
+            x=1;
+            return x;
+        } catch (Exception e) {
+            x=2;
+            return x;
+        } finally {
+            x=3;
+        }
+    }
+
+    public static void main(String[] args) {
+        TryCatchDemo tryCatchDemo = new TryCatchDemo();
+        System.out.println(tryCatchDemo.test());
+    }
+}

target/maven-archiver/pom.properties

@@ -0,0 +1,3 @@
+artifactId=java-learning
+groupId=com.kuaslab
+version=1.0-SNAPSHOT

target/maven-status/maven-compiler-plugin/compile/compile/createdFiles.lst

@@ -0,0 +1,54 @@
+jvm/createthread/CreateByExecutorService.class
+threaddemo/WeakReferenceExample.class
+feature/ReduceTest.class
+jvm/createthread/CreateByThreadGroup.class
+jvm/ConstantPoolDemo.class
+jvm/debugtool/JHSDBTestCase$Test.class
+threaddemo/DeadLockFixDemo.class
+threaddemo/lock/CLH.class
+threaddemo/MultiThreadDemo.class
+jvm/debugtool/DeadLockDemo$SyncAddRunnable.class
+threaddemo/ProcessDemo.class
+threaddemo/VolatileAtomicDemo.class
+jvm/createthread/CreateByTimer$1.class
+jvm/createthread/CreateByAnonymousClass.class
+threaddemo/ThreadStateWithWait.class
+jvm/gc/PrintMemoryAddress.class
+jvm/classfile/TestClass.class
+jvm/createthread/CreateByForkJoin.class
+jvm/ShowObjectHeader.class
+threaddemo/ThreadStateWithJoin.class
+threaddemo/SafeVolatileDemo.class
+threaddemo/ThreadShareVariable.class
+threaddemo/ThreadStateWithSync.class
+jvm/oom/HeapOOM.class
+threaddemo/ThreadStateWithLockSupport.class
+jvm/oom/JavaVMStackSOF.class
+threaddemo/DeadlockDemo.class
+jvm/oom/HeapOOM$OOMObject.class
+threaddemo/InterruptTest.class
+io/ReadAndUpload$1.class
+main/java/recursive/TreeStructure.class
+jvm/gc/MemoryAllocationYoung.class
+jvm/createthread/CreateByTimer.class
+jvm/createthread/CreateByThread.class
+io/FileChunkInitReq.class
+threaddemo/lock/CLHDemo.class
+main/java/recursive/TreeNode.class
+jvm/gc/TenuringThreshold.class
+threaddemo/dataracing/CASByAtomicInteger.class
+jvm/gc/ReferenceCountingGC.class
+jvm/createthread/CreateByRunnable.class
+jvm/createthread/CreateByCompletableFuture.class
+io/ReadAndUpload.class
+jvm/debugtool/JHSDBTestCase.class
+jvm/debugtool/DeadLockDemo.class
+threaddemo/lock/CLH$Node.class
+jvm/debugtool/JHSDBTestCase$ObjectHolder.class
+jvm/VarHandleDemo.class
+main/java/jvm/ObjectCreate.class
+jvm/createthread/CreateByFutureTask.class
+threaddemo/ThreadLocalDemo.class
+jvm/createthread/CreateByAnonymousClass$1.class
+threaddemo/dataracing/SyncDemo.class
+jvm/createthread/CreateByCallable.class

target/maven-status/maven-compiler-plugin/compile/compile/inputFiles.lst

@@ -0,0 +1,46 @@
+/home/admin/projects/java_test/src/main/java/jvm/createthread/CreateByTimer.java
+/home/admin/projects/java_test/src/main/java/jvm/ConstantPoolDemo.java
+/home/admin/projects/java_test/src/main/java/threaddemo/WeakReferenceExample.java
+/home/admin/projects/java_test/src/main/java/jvm/createthread/CreateByAnonymousClass.java
+/home/admin/projects/java_test/src/main/java/recursive/TreeNode.java
+/home/admin/projects/java_test/src/main/java/jvm/ObjectCreate.java
+/home/admin/projects/java_test/src/main/java/threaddemo/ThreadShareVariable.java
+/home/admin/projects/java_test/src/main/java/threaddemo/dataracing/SyncDemo.java
+/home/admin/projects/java_test/src/main/java/threaddemo/ThreadStateWithWait.java
+/home/admin/projects/java_test/src/main/java/jvm/gc/TenuringThreshold.java
+/home/admin/projects/java_test/src/main/java/threaddemo/SafeVolatileDemo.java
+/home/admin/projects/java_test/src/main/java/jvm/createthread/CreateByForkJoin.java
+/home/admin/projects/java_test/src/main/java/jvm/gc/PrintMemoryAddress.java
+/home/admin/projects/java_test/src/main/java/threaddemo/InterruptTest.java
+/home/admin/projects/java_test/src/main/java/threaddemo/lock/CLH.java
+/home/admin/projects/java_test/src/main/java/threaddemo/DeadLockFixDemo.java
+/home/admin/projects/java_test/src/main/java/threaddemo/MultiThreadDemo.java
+/home/admin/projects/java_test/src/main/java/jvm/createthread/CreateByCompletableFuture.java
+/home/admin/projects/java_test/src/main/java/jvm/createthread/CreateByRunnable.java
+/home/admin/projects/java_test/src/main/java/jvm/debugtool/JHSDBTestCase.java
+/home/admin/projects/java_test/src/main/java/jvm/debugtool/DeadLockDemo.java
+/home/admin/projects/java_test/src/main/java/io/ReadAndUpload.java
+/home/admin/projects/java_test/src/main/java/threaddemo/ProcessDemo.java
+/home/admin/projects/java_test/src/main/java/threaddemo/dataracing/CASByAtomicInteger.java
+/home/admin/projects/java_test/src/main/java/threaddemo/ThreadStateWithSync.java
+/home/admin/projects/java_test/src/main/java/jvm/createthread/CreateByExecutorService.java
+/home/admin/projects/java_test/src/main/java/threaddemo/ThreadLocalDemo.java
+/home/admin/projects/java_test/src/main/java/feature/ReduceTest.java
+/home/admin/projects/java_test/src/main/java/io/FileChunkInitReq.java
+/home/admin/projects/java_test/src/main/java/threaddemo/VolatileAtomicDemo.java
+/home/admin/projects/java_test/src/main/java/jvm/createthread/CreateByFutureTask.java
+/home/admin/projects/java_test/src/main/java/threaddemo/ThreadStateWithLockSupport.java
+/home/admin/projects/java_test/src/main/java/threaddemo/lock/CLHDemo.java
+/home/admin/projects/java_test/src/main/java/jvm/oom/HeapOOM.java
+/home/admin/projects/java_test/src/main/java/jvm/createthread/CreateByThreadGroup.java
+/home/admin/projects/java_test/src/main/java/threaddemo/ThreadStateWithJoin.java
+/home/admin/projects/java_test/src/main/java/jvm/gc/ReferenceCountingGC.java
+/home/admin/projects/java_test/src/main/java/recursive/TreeStructure.java
+/home/admin/projects/java_test/src/main/java/jvm/VarHandleDemo.java
+/home/admin/projects/java_test/src/main/java/jvm/createthread/CreateByThread.java
+/home/admin/projects/java_test/src/main/java/jvm/oom/JavaVMStackSOF.java
+/home/admin/projects/java_test/src/main/java/jvm/createthread/CreateByCallable.java
+/home/admin/projects/java_test/src/main/java/jvm/gc/MemoryAllocationYoung.java
+/home/admin/projects/java_test/src/main/java/threaddemo/DeadlockDemo.java
+/home/admin/projects/java_test/src/main/java/jvm/classfile/TestClass.java
+/home/admin/projects/java_test/src/main/java/jvm/ShowObjectHeader.java