[java] wait until all threads finish their work in java

I had similar situation , where i had to wait till all child threads complete its execution then only i could get the status result for each of them .. hence i needed to wait till all child thread completed.

below is my code where i did multi-threading using

 public static void main(String[] args) {
        List<RunnerPojo> testList = ExcelObject.getTestStepsList();//.parallelStream().collect(Collectors.toList());
        int threadCount = ConfigFileReader.getInstance().readConfig().getParallelThreadCount();
        System.out.println("Thread count is : =========  " + threadCount); // 5

        ExecutorService threadExecutor = new DriverScript().threadExecutor(testList, threadCount);


        boolean isProcessCompleted = waitUntilCondition(() -> threadExecutor.isTerminated()); // Here i used waitUntil condition 

        if (isProcessCompleted) {
            testList.forEach(x -> {
                System.out.println("Test Name: " + x.getTestCaseId());
                System.out.println("Test Status : " + x.getStatus());
                System.out.println("======= Test Steps ===== ");

                x.getTestStepsList().forEach(y -> {
                    System.out.println("Step Name: " + y.getDescription());
                    System.out.println("Test caseId : " + y.getTestCaseId());
                    System.out.println("Step Status: " + y.getResult());
                    System.out.println("\n ============ ==========");
                });
            });
        }

Below method is for distribution of list with parallel proccessing

// This method will split my list and run in a parallel process with mutliple threads
    private ExecutorService threadExecutor(List<RunnerPojo> testList, int threadSize) {
        ExecutorService exec = Executors.newFixedThreadPool(threadSize);
        testList.forEach(tests -> {
            exec.submit(() -> {
                driverScript(tests);
            });
        });
        exec.shutdown();
        return exec;
    }

This is my wait until method: here you can wait till your condition satisfies within do while loop . in my case i waited for some max timeout . this will keep checking until your threadExecutor.isTerminated() is true with polling period of 5 sec.

    static boolean waitUntilCondition(Supplier<Boolean> function) {
        Double timer = 0.0;
        Double maxTimeOut = 20.0;

        boolean isFound;
        do {
            isFound = function.get();
            if (isFound) {
                break;
            } else {
                try {
                    Thread.sleep(5000); // Sleeping for 5 sec (main thread will sleep for 5 sec)
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
                timer++;
                System.out.println("Waiting for condition to be true .. waited .." + timer * 5 + " sec.");
            }
        } while (timer < maxTimeOut + 1.0);

        return isFound;
    }