为什么温度湿度都显示0

public class Weather {

private int temperature;// 温度

private int humidity;// 湿度

    boolean flag=false;

public int getTemperature() {

return temperature;

}

public void setTemperature(int temperature) {

this.temperature = temperature;

}

public int getHumidity() {

return humidity;

}

public void setHumidity(int humidity) {

this.humidity = humidity;

}

// 生成天气数据的方法

public synchronized void generate() {

int i=1;

while(i<=100) {

if(flag) {

try {

wait();

} catch (InterruptedException e) {

// TODO Auto-generated catch block

e.printStackTrace();

}

}

this.setTemperature((int)Math.random()*100);

this.setHumidity((int)Math.random()*40);

try {

Thread.sleep(5000);

} catch (InterruptedException e) {

// TODO Auto-generated catch block

e.printStackTrace();

}

System.out.println("生成天气数据:"+this.toString());

notifyAll();

flag=true;

i++;

}

}

//读取天气的方法

public synchronized void read() {

int i=1;

while(i<=100) {

if(!flag) {

try {

wait();

} catch (InterruptedException e) {

// TODO Auto-generated catch block

e.printStackTrace();

}

}

try {

Thread.sleep(100);

} catch (InterruptedException e) {

// TODO Auto-generated catch block

e.printStackTrace();

}

System.out.println("读取天气数据:"+this.toString());

notifyAll();

flag=false;

i++;

}

}

    //重写toString方法

public String toString() {

return "温度:"+temperature+",湿度:"+humidity;

}