멀티스레드 참고 & 과제 만드는 중..

원주율을 구하여 출력하는 멀티스레드 예제

class CalcThread extends Thread 

{

SharedArea sharedArea;//이걸 선언해서 공유 영역에 접근하도록 한다. 클래스형 변수(객체)선언

public void run()

{

double total = 0.0;

for(int i=1; i<1000000000; i+=2){

if(i/2 % 2 ==0) total +=1.0/i;

else total -=1.0/i;

}

sharedArea.result = total*4; //원주율(3.14를 공유영역에 넣음)

sharedArea.isReady = true;

}

}

//--------------------------------------------------------------------------------------------------

class SharedArea 

{

double result;

boolean isReady; //new Challenger!!

}

//--------------------------------------------------------------------------------------------------

class PrintThread extends Thread {

    SharedArea sharedArea;

    public void run() {

        while(sharedArea.isReady!=true) continue; //new challnger!!

System.out.println(sharedArea.result);

    }

}

//--------------------------------------------------------------------------------------------------

class MultiThreadExample5 

{

public static void main(String[] args) 

{

CalcThread thread1 = new CalcThread();

PrintThread thread2 = new PrintThread();

SharedArea obj = new SharedArea();

thread1.sharedArea = obj;

thread2.sharedArea=obj;

thread1.start();

thread2.start();

}

}

계좌 클래스 Syncronized함수로 동기화하기

class Account {

    String accountNo;    // 계좌번호

    String ownerName;    // 예금주 이름

    int balance;         // 잔액

    Account(String accountNo, String ownerName, int balance) {   

        this.accountNo = accountNo; 

        this.ownerName = ownerName;  

        this.balance = balance;       

    }

    void  deposit(int amount)  {  //입금

        balance += amount;

    }

    int withdraw(int amount) {  //출금

        if (balance < amount)

            return 0;

        balance -= amount;

        return amount;

    }

}

//--------------------------------------------------------------------------------------------------

class SharedArea 

{

Account account1;

Account account2;

}

//--------------------------------------------------------------------------------------------------

class PrintThread extends Thread //account 클래스랑 연관

{

SharedArea sharedArea;

PrintThread(SharedArea area){//생성자

sharedArea = area;

}

public void run(){

for(int cnt=0; cnt<3; cnt++){

synchronized(sharedArea){

//이걸 써둔 얘들끼리 동기를 맞춘다. 안하면 결과값이 정확하지 않을수도 있다.

int sum = sharedArea.account1.balance + sharedArea.account2.balance;

System.out.println("계좌 잔액 합계 : " + sum);

}

try{

Thread.sleep(100);

}

catch(InterruptedException e){

System.out.println(e.getMessage());

}

}

}

}

//--------------------------------------------------------------------------------------------------

class TransferThread extends Thread 

{

SharedArea sharedArea;

TransferThread(SharedArea area){//생성자

sharedArea=area;

}

public void run(){

for(int cnt=0; cnt<12; cnt++){

synchronized(sharedArea){

sharedArea.account1.withdraw(1000000);

System.out.print("이몽룡 계좌 : 100만원 인출,");

sharedArea.account2.deposit(1000000);

System.out.println("성춘향 계좌 : 100만원 입금,");

}

}

}

}

//--------------------------------------------------------------------------------------------------

class MultithreadExample5

{

    public static void main(String[] args) 

{

        SharedArea area = new SharedArea();

        area.account1 = new Account("111-111-1111", "이몽룡", 20000000);

        area.account2 = new Account("222-222-2222", "성춘향", 10000000);

        TransferThread thread1 = new TransferThread(area);

        PrintThread thread2 = new PrintThread(area);

        thread1.start(); //Transfer

        thread2.start(); //PrintThread

//System.out.println(area.account2.ownerName);

    }

}