为什么我这个永远都不会从1开始

public class Weather {

int wd;
    int sd;
    boolean flag = false;

    public synchronized void get(){

if (!flag){
try {
                wait();
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
        System.out.println("读取天气速度：【温度："+wd+",湿度："+sd+"】");
        flag = false;
        notifyAll();
    }

public synchronized void set(int wd,int sd){
if (flag){
try {
                wait();
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
this.sd = sd;
        this.wd = wd;

        System.out.println("生成取天气速度：【温度："+wd+",湿度："+sd+"】");
        flag = true;
        notifyAll();
    }


}

public class GenerateWeather extends Thread{

    Weather weather;

    public GenerateWeather(Weather weather) {
this.weather = weather;
    }

@Override
    public void run() {
int wd = 0,sd = 0;
        while (true)

weather.set(wd++,sd++);
    }
}

public class ReadWeather extends Thread{

    Weather weather;


    public ReadWeather(Weather weather) {
this.weather = weather;
    }

@Override
    public void run() {
while (true){
weather.get();
        }
    }
}

public class main {
public static void main(String[] args) {
        Weather weather = new Weather();
        GenerateWeather generateWeather = new GenerateWeather(weather);
        ReadWeather readWeather = new ReadWeather(weather);
        generateWeather.start();
        readWeather.start();

    }
}