1、当其他非守护线程完成时，守护线程将自行结束。
2、任何线程都可以成为守护线程。通过调用Thread.setdaemon()来声明一个线程是一个守护线程。线程的共性是只有在非守护线程还在工作时才有意义。
实例
/**
* Creates ten threads to search for the maximum value of a large matrix.
* Each thread searches one portion of the matrix.
*/
public class TenThreads {
private static class WorkerThread extends Thread {
int max = Integer.MIN_VALUE;
int[] ourArray;
public WorkerThread(int[] ourArray) {
this.ourArray = ourArray;
}
// Find the maximum value in our particular piece of the array
public void run() {
for (int i = 0; i < ourArray.length; i++)
max = Math.max(max, ourArray[i]);
}
public int getMax() {
return max;
}
}
public static void main(String[] args) {
WorkerThread[] threads = new WorkerThread[10];
int[][] bigMatrix = getBigHairyMatrix();
int max = Integer.MIN_VALUE;
// Give each thread a slice of the matrix to work with
for (int i=0; i < 10; i++) {
threads[i] = new WorkerThread(bigMatrix[i]);
threads[i].start();
}
// Wait for each thread to finish
try {
for (int i=0; i < 10; i++) {
threads[i].join();
max = Math.max(max, threads[i].getMax());
}
}
catch (InterruptedException e) {
// fall through
}
System.out.println("Maximum value was " + max);
}
}推荐操作环境：windows7系统、java10版，DELL G3电脑。
