Java interview question: if an array [2, 4, 6, 2,] is known, sort the Array (in descending order, the tool class cannot be used for sorting) and create two threads to output the sorted array alternately, thread name customization,

Java interview question: if an array [2, 4, 6, 2,] is known, sort the Array (in descending order, the tool class cannot be used for sorting) and create two threads to output the sorted array alternately, thread name customization,

Package com. swift; import java. util. arrays; import java. util. comparator; public class ArrayThread_Test {public static void main (String [] args) {/** an array [,] is known and sorted (in descending order, the tool class cannot be used for sorting). Two threads are created to output the sorted array alternately. The thread name is customized */Integer [] arr = new Integer [] {2, 4, 6, 2, 1, 5}; // sort Arrays by array tool class. sort (arr, new Comparator <Integer> () {@ Override public int compare (Integer arg0, Integer arg1) {int num = arg 1-arg0; return num ;}}); // two-line quick sorting Integer [] arr2 = new Integer [] {7, 2, 4, 16, 2, 13, 5}; kuaisu (arr2, 0, arr2.length-1); for (Integer I: arr2) {System. out. print (I + "~ "+" \ R \ n ");} ArrayThread a = new ArrayThread (arr); Thread t1 = new Thread (a," Thread 1 "); thread t2 = new Thread (a, "Thread 2"); t1.start (); t2.start ();} private static void kuaisu (Integer [] arr2, int left, int right) {if (left> = right) // stop return when there is only one number after recursion; int key = arr2 [left]; int I = left; int j = right; while (I! = J) {while (arr2 [j]> key & I <j) {j --;} while (arr2 [I] <= key & I <j) {I ++;} if (I <j) {int temp; temp = arr2 [I]; arr2 [I] = arr2 [j]; arr2 [j] = temp;} arr2 [left] = arr2 [I]; arr2 [I] = key; kuaisu (arr2, left, j-1 ); kuaisu (arr2, I + 1, right );}}

The above is the test class, which performs fast sorting and tool class sorting.

Creates an object that implements the Runnable interface and transmits parameters.

Create two threads and start the thread

Package com. swift; public class ArrayThread implements Runnable {Integer [] arr; int index = 0; boolean flag = true; public ArrayThread (Integer [] arr) {this. arr = arr ;}@ Override public void run () {// for Loop is not suitable for multithreading. Although the content of an object is also executed multiple times, because the lock is in the for loop while (true) {synchronized (this) {if (index> = arr. length) {this. Y (); // Why can't other threads wake up? The virtual machine does not stop break;} System. out. println (Thread. currentThread (). getName () + "output" + arr [index]); index ++; if (flag) {flag = false; this. Y (); try {this. wait ();} catch (InterruptedException e) {e. printStackTrace () ;}} else {flag = true; this. Y (); try {this. wait ();} catch (InterruptedException e) {e. printStackTrace ();}}}}}}

Wake up other threads through notify, stop their own threads through wait, and use the flag to switch threads alternately.