ArrayList多线程安全解决办法

经测试可以解决线程安全问题

public class Main {
    

    public static volatile Boolean flag = false;

    public static void main(String[] args) {
    
        ArrayList arrayList = new ArrayList();
        for (int i = 0; i < 100; i++) {
    
            arrayList.add(Integer.toString(i));
        }
        Iterator i = arrayList.listIterator();
        for (int x = 0; x < 100; x++) {
    
            MyThread myThread = new MyThread(i, arrayList);
            myThread.start();
        }
        flag = true;
    }

    static class MyThread extends Thread {
    
        private Iterator i;
        private ArrayList arrayList;

        public MyThread(Iterator i, ArrayList arrayList) {
    
            this.i = i;
            this.arrayList = arrayList;
        }

        @Override
        public void run() {
    
            while (!flag) {
    
            }
            while (i.hasNext()) {
    
                synchronized (flag) {
    
                    if (i.hasNext()) {
    
                        Object o = i.next();
                        System.out.println(currentThread().getName() + ":" + o + ":" + o.hashCode());
                        i.remove();
                    }
                }
// try {
    
// sleep(10);
// } catch (InterruptedException e) {
    
// e.printStackTrace();
// }
            }
        }

    }
}

运行结果：

Thread-59:89:1793
Thread-55:90:1815
Thread-63:91:1816
Thread-70:92:1817
Thread-75:93:1818
Thread-71:94:1819
Thread-74:95:1820
Thread-79:96:1821
Thread-83:97:1822
Thread-82:98:1823
Thread-86:99:1824

Process finished with exit code 0