wait(), notify(), notifyAll()

- 동기화와 wait(), notify()

-> 데이터의 동기화와 관련해 쓰레드를 미세하게 제어하는 메서드

=> wait() : 쓰레드를 Not Runnable 영역으로 보냄

=> notify(), notifyAll(), : wait() 에 의해 Not Runnable영역으로 보내진 쓰레드를 Runnable영역으로 보냄

=> synchronized 선언된 곳에서 사용

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import java.util.Vector;

class SyncStack{

private Vector buffer = new Vector();

public synchronized char pop(){

char c;

while(buffer.size() == 0){

try{

System.out.println("stack대기:");

this.wait();

}catch (Exception e) {

// TODO: handle exception

}

}

Character cr = ( (Character) buffer.remove(buffer.size() - 1));

c = cr.charValue();

System.out.println("stack삭제:" + c);

return c;

}

public synchronized void push(char c){

this.notify();

Character charObj = new Character(c);

buffer.addElement(charObj);

System.out.println("stack삽입:" + c);

}

}

class PopRunnable extends Thread{

@Override

public void run() {

// TODO Auto-generated method stub

SyncTest.ss.pop();

}

}

class PushRunnable extends Thread{

private char c;

public PushRunnable(char c){

this.c = c;

}

@Override

public void run() {

// TODO Auto-generated method stub

SyncTest.ss.push(c);

}

}

public class SyncTest {

public static SyncStack ss = new SyncStack();

public static void main(String[] args) {

new PushRunnable('J').start();

new PushRunnable('A').start();

new PushRunnable('V').start();

new PushRunnable('A').start();

new PushRunnable('O').start();

new PopRunnable().start(); // O

new PopRunnable().start(); // A

new PopRunnable().start(); // V

new PopRunnable().start(); // A

new PopRunnable().start(); // J

new PopRunnable().start(); // 대기 상태

try{

Thread.sleep(5000);

}catch (Exception e) {

// TODO: handle exception

}

System.out.println("======= passed 5 seconds======");

new PushRunnable('K').start();

}

}

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