多線程取父線程及當前線程

import java.lang.reflect.Field;

/**
 * description:
 *
 * @author: dawn.he QQ:       905845006
 * @email: dawn.he@cloudwise.com
 * @email: 905845006@qq.com
 * @date: 2019/12/4    11:19 PM
 */
public class aa {
    public static void main(String[] args) {


        ThreadGroup currentGroup = Thread.currentThread().getThreadGroup();

        System.out.println("main線程:" + Thread.currentThread().getId() + ":");
        Field threadsField = null;
        Field nthreadsField = null;
        nthreadsField = getField(currentGroup, "nthreads");
        threadsField = getField(currentGroup, "threads");
        try {

            Object nthread = nthreadsField.get(currentGroup);
            int a = Integer.parseInt(nthread.toString());


            Object[] o = (Object[]) threadsField.get(currentGroup);
            System.out.println(o.length);
            Thread[] thread = (Thread[]) o;
            if (a == 1) {
                System.out.println("反射main線程：" + thread[a - 1].getId() + "------------");
                System.out.println("反射main線程父線程：null-------");

            } else {
                System.out.println("反射當前線程：" + thread[a - 1].getId() + "------------");
                System.out.println("反射當前父線程：" + thread[a - 2].getId() + "------------");
            }

        } catch (IllegalAccessException e) {
            e.printStackTrace();
        }
        //-------------------------
        new Thread(new Runnable() {
            public void run() {
                ThreadGroup currentGroup = Thread.currentThread().getThreadGroup();

                System.out.println("線程1:" + Thread.currentThread().getId() + ":");
                Field threadsField = null;
                Field nthreadsField = null;
                nthreadsField = getField(currentGroup, "nthreads");
                threadsField = getField(currentGroup, "threads");
                try {

                    Object nthread = nthreadsField.get(currentGroup);
                    int a = Integer.parseInt(nthread.toString());


                    Object[] o = (Object[]) threadsField.get(currentGroup);
                    System.out.println(o.length);
                    Thread[] thread = (Thread[]) o;
                    if (a == 1) {
                        System.out.println("反射main線程：" + thread[a - 1].getId() + "------------");
                        System.out.println("反射main線程父線程：null-------");

                    } else {
                        System.out.println("反射當前線程1：" + thread[a - 1].getId() + "------------");
                        System.out.println("反射當前父線程1：" + thread[a - 2].getId() + "------------");
                    }

                } catch (IllegalAccessException e) {
                    e.printStackTrace();
                }

                new Thread(new Runnable() {
                    public void run() {
                        ThreadGroup currentGroup = Thread.currentThread().getThreadGroup();

                        System.out.println("線程2:" + Thread.currentThread().getId() + ":");
                        Field threadsField = null;
                        Field nthreadsField = null;
                        nthreadsField = getField(currentGroup, "nthreads");
                        threadsField = getField(currentGroup, "threads");
                        try {

                            Object nthread = nthreadsField.get(currentGroup);
                            int a = Integer.parseInt(nthread.toString());


                            Object[] o = (Object[]) threadsField.get(currentGroup);
                            System.out.println(o.length);
                            Thread[] thread = (Thread[]) o;
                            if (a == 1) {
                                System.out.println("反射main線程：" + thread[a - 1].getId() + "------------");
                                System.out.println("反射main線程父線程：null-------");

                            } else {
                                System.out.println("反射當前線程2：" + thread[a - 1].getId() + "------------");
                                System.out.println("反射當前父線程2：" + thread[a - 2].getId() + "------------");
                            }

                        } catch (IllegalAccessException e) {
                            e.printStackTrace();
                        }
                        new Thread(new Runnable() {
                            public void run() {
                                ThreadGroup currentGroup = Thread.currentThread().getThreadGroup();

                                System.out.println("線程3:" + Thread.currentThread().getId() + ":");
                                Field threadsField = null;
                                Field nthreadsField = null;
                                nthreadsField = getField(currentGroup, "nthreads");
                                threadsField = getField(currentGroup, "threads");
                                try {

                                    Object nthread = nthreadsField.get(currentGroup);
                                    int a = Integer.parseInt(nthread.toString());


                                    Object[] o = (Object[]) threadsField.get(currentGroup);
                                    System.out.println(o.length);
                                    Thread[] thread = (Thread[]) o;
                                    if (a == 1) {
                                        System.out.println("反射main線程：" + thread[a - 1].getId() + "------------");
                                        System.out.println("反射main線程父線程：null-------");

                                    } else {
                                        System.out.println("反射當前線程3：" + thread[a - 1].getId() + "------------");
                                        System.out.println("反射當前父線程3：" + thread[a - 2].getId() + "------------");
                                    }

                                } catch (IllegalAccessException e) {
                                    e.printStackTrace();
                                }
                                while (true) {

                                }
                            }
                        }).start();
                        while (true) {

                        }
                    }
                }).start();
                while (true) {

                }
            }

        }).start();

        while (true) {

        }
    }

    public static Field getField(ThreadGroup group, String field) {
        try {
            Field field1;
            field1 = group.getClass().getDeclaredField(field);
            if (!field1.isAccessible()) {
                field1.setAccessible(true);
            }
            return field1;
        } catch (NoSuchFieldException e) {
            e.printStackTrace();
        }
        return null;
    }
}