Java interview written questions: Design 4 threads, of which two threads to J 1 each time, the other two threads to j each reduction of 1. Write out the program

Ask: Design 4 threads, where two threads add 1 to J each time, and two threads reduce the J each time by 1. Write out the program.

Answer: The following procedure uses the internal class to implement the thread, to the J increases or decreases when does not consider the order question.

public class threadtest1{Private int J. public static void Main (String args[]) {ThreadTest1 tt=new ThreadTest1 (); Inc Inc=tt.new Inc. (); Dec dec=tt.new Dec (); for (int i=0;i<2;i++) {thread t=new thread (inc); T.start (); t=new thread (DEC); T.start ();}} Private synchronized Void Inc () {j + +; System.out.println (Thread.CurrentThread (). GetName () + "-inc:" +j);} private synchronized void Dec () {j--; System.out.println (Thread.CurrentThread (). GetName () + "-dec:" +j);} Class INC implements runnable{public void run () {for int i=0;i<100;i++) {Inc ();}} class Dec implements runnable{p ublic void Run () {for (int i=0;i<100;i++) {Dec ()}}} }