程序不会自行终止

Question

我编写了一个使用线程来计算数字pi的程序。不幸的是，我现在遇到的问题是，程序在计算之后以及执行main方法中的所有代码后都不会终止自身。有人可以提示我可能是什么吗？

        CalculatePi pi = new Leibniz();
    pi.startCalculation(4); //starts four threads

    long timeStart = System.currentTimeMillis();
    int i = 0;
    while(i < MAX_PRECISION) {
        someDelay(); // just some sleep() delay
        i++;
    }
    long timeStop = System.currentTimeMillis();
    pi.stopCalculation(); //stops all threads
    System.out.println((timeStop - timeStart) + " ms");
    System.out.println(pi.getValue());
    //After this code the program keeps running

编辑：

    public void run() {

    BigDecimal counter = new BigDecimal("1");

    while( !flag )  {
            // counter % numThreads == threadRemainder
        if(counter.intValue() % numOfAllThreads == numOfThread)
            // if counter % 2 == 1 , get all odd numbers
            if(counter.remainder(new BigDecimal("2")).equals(BigDecimal.ONE)) {
                // calculate this.value = this.value + 1 / (2 * counter + 1)
                threadResult = threadResult.add(BigDecimal.ONE.divide(((new BigDecimal("2").multiply(counter).subtract(BigDecimal.ONE))), 1000, RoundingMode.HALF_UP));
            }else {
                // calculate this.value = this.value - 1 / (2 * counter + 1)
                threadResult = threadResult.subtract(BigDecimal.ONE.divide(((new BigDecimal("2").multiply(counter).subtract(BigDecimal.ONE))), 1000, RoundingMode.HALF_UP));
            }
        // Inkrement counter to check next number
        counter = counter.add(new BigDecimal("1"));
    }
}

启动线程的方法：

    // Multi-Threading
public boolean startCalculation(int numThreads) {
    //The executor handles the thread execution
    ExecutorService executorService = Executors.newFixedThreadPool(numThreads);
    // Set Thread-Array length to numThreads
    workers = new LeibnizThread[numThreads];
    for (int i = 0; i < numThreads; i++) {
        workers[i] = new LeibnizThread(numThreads, i);
        // //executorService starts Thread by calling run()
        executorService.submit(workers[i]);
    }
    return true;
}

Answer 1

上面的代码片段使while循环运行，只要'flag'的值为false。

'

flag'的值在循环中未更改。这使循环无限期地运行。
在某种情况下将标志的值更改为'true'将中断while循环，并允许程序按预期终止。
以下是打破循环的例子：
// Example 1:  Break the loop after a maximum of 100 iterations.
int iteration = 1;
while ( !flag ) {
    //  ...


    // Force the program to terminate after a maximum of 100 iterations.
    iteration++;
    if (iteration == 100) {
        break;
    }
}


// Example 2:  Break the loop by changing flag when some condition is true.

while ( !flag ) {
    //  ...

    // Change flag on a condition, so that the loop will break.

    if ( // some condition ) {
        flag = true;
    }
}