fork join framework example

Author: serdaralkancode

src/main/java/tr/salkan/code/java/threadExecutor/example/forkJoin/recursiveActionExample/ExampleTask.java

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+package tr.salkan.code.java.threadExecutor.example.forkJoin.recursiveActionExample;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.concurrent.ForkJoinPool;
+import java.util.concurrent.RecursiveAction;
+
+public class ExampleTask extends RecursiveAction {
+
+    private static final long serialVersionUID = 1L;
+
+    private List<Integer> numberList;
+
+    public ExampleTask(List<Integer> numberList) {
+        this.numberList = numberList;
+    }
+
+
+    @Override
+    protected void compute() {
+
+        System.out.println("numberList :" + numberList);
+        if(numberList != null && numberList.size() > 1) {
+            List<Integer> oneNum = new ArrayList<Integer>();
+            oneNum.add(numberList.remove(numberList.size()-1));
+
+            ExampleTask subTaskOne = new ExampleTask(oneNum);
+            ExampleTask subTaskTwo = new ExampleTask(numberList);
+
+            invokeAll(subTaskOne, subTaskTwo);
+
+        }else {
+
+            computeFact(numberList.get(0));
+        }
+
+    }
+
+    void computeFact(int num) {
+
+        System.out.println("computeFact :" + num);
+
+        int fact = 1;
+
+        for(int i = 1; i <=num; i++)
+        {
+            fact = fact * i;
+        }
+
+
+        System.out.println("Thread "+Thread.currentThread().getId()
+                +" Number "+num
+                +"factorial "+fact);
+    }
+
+    public static void main(String[] args) {
+
+        ForkJoinPool fjp = new ForkJoinPool();
+
+        List<Integer> list = new ArrayList<>();
+        list.add(5);
+        list.add(8);
+        list.add(11);
+        list.add(3);
+
+        ExampleTask exampleTask = new ExampleTask(list);
+
+        fjp.invoke(exampleTask);
+
+        //or using
+
+        //fjp.execute(exampleTask);
+        // exampleTask.join();
+    }
+}

src/main/java/tr/salkan/code/java/threadExecutor/example/forkJoin/recursiveTaskExample/ExampleTask.java

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+package tr.salkan.code.java.threadExecutor.example.forkJoin.recursiveTaskExample;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.concurrent.ForkJoinPool;
+import java.util.concurrent.RecursiveTask;
+
+public class ExampleTask extends RecursiveTask<String> {
+
+    private static final long serialVersionUID = 1L;
+
+    private List<Double> salaries;
+
+    public ExampleTask(List<Double> salaries) {
+        this.salaries = salaries;
+    }
+
+    @Override
+    protected String compute() {
+
+        if(salaries.size() == 1)
+        {
+            return computeTaxAndGetSalary(salaries.get(0));
+        }
+
+        List<Double> oneSalary = salaries.subList(0, salaries.size()/2);
+        List<Double> twoSalary = salaries.subList(salaries.size()/2,
+                salaries.size());
+
+        ExampleTask taskOne = new ExampleTask(oneSalary);
+        taskOne.fork();
+
+        ExampleTask taskTwo = new ExampleTask(twoSalary);
+
+        return taskTwo.compute()+"," + taskOne.join();
+
+    }
+
+    String computeTaxAndGetSalary(Double salary) {
+
+        Double taxRate = 1.0;
+
+        if(salary < 2000)
+        {
+            taxRate = 7.5;
+        }
+        else if( salary >=2000 || salary < 5000)
+        {
+            taxRate = 12.5;
+        }
+        else if ( salary >= 5000)
+        {
+            taxRate = 20.5;
+        }
+
+        Double money = salary - ((salary*taxRate)/100);
+        return "salary : " + salary + " taxRate :" + taxRate + " result : " + money;
+    }
+
+    public static void main(String[] args) {
+
+        ForkJoinPool forkJoinPool = new ForkJoinPool();
+
+        List<Double> salaryList = new ArrayList<Double>();
+        salaryList.add(3000.0);
+        salaryList.add(2000.0);
+        salaryList.add(1800.0);
+        salaryList.add(9000.0);
+
+        ExampleTask exampleTask = new ExampleTask(salaryList);
+
+        String coupons = forkJoinPool.invoke(exampleTask);
+        System.out.println(coupons);
+
+    }
+}