（如發現問題，請幫忙指出，謝謝）使用多執行緒計算階乘累加 1！+2！+3！+…+19!+20!。其中一個執行緒計算階乘，另一執行緒實現累加並輸出結果。

class Info{
    double sum=1;
    double count =0;
    private boolean flag=false;
    double count1;
    public synchronized void set(double sum){
        if(!flag){
            try{
                super.wait();
            }
 
 catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
        this.setSum(sum);
        try{
            Thread.sleep(300);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        this.setCount(count);
        flag=false;
        super
 
.notify();
    }
    public synchronized void get(double count){
        if(flag){
            try{
                super.wait();
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
        try{
            Thread.sleep(300);
        } catch (InterruptedException
 
 e) {
            e.printStackTrace();
        }
        flag=true;
        super.notify();
    }

    public double getCount() {
        return count;
    }

    public void setCount(double count) {
        this.count = count;
    }

    public void setSum(double sum) {
        this.sum = sum;
    }

    public double getSum() {
        return sum;
    }
}

class Producer implements Runnable {
    private Info info = null;
    public Producer(Info info) {
        this.info = info;
    }

    @Override
    public void run() {
        int i;
        boolean flag = true;
        if (flag) {
            for (i = 1; i <= 20; i++) {
                try {
                    this.info.sum=1;
                    for (int j = 1; j <= i; j++) {
                        this.info.sum *= j;
                        if(i==20){
                            this.info.count1=this.info.sum;
                        }
                    }
                    Thread.sleep(90);
                    System.out.println(i + "!為" + this.info.sum);
                    this.info.set(this.info.sum);
                }catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
            flag=true;
        }else {
            try{
                Thread.sleep(90);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            flag=false;
        }
    }
}

class Consumer implements Runnable{
    private Info info=null;
    private double count1=0;
    public Consumer(Info info){
        this.info=info;
    }
    @Override
    public void run() {
        for(int i=1;i<=20;i++){      
            try{
                Thread.sleep(100);
                this.info.count+=this.info.sum;
                this.info.get(this.info.count);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
        System.out.println("計算結果為:"+(this.info.count+this.info.count1));
    }
}

public class TestX {
    public static void main(String args[]){
        Info i=new Info();
        Producer pro=new Producer(i);
        Consumer con=new Consumer(i);
        new Thread(pro).start();
        new Thread(con).start();
    }
}