int 类的计算，不好犯这种低级错误

public double getRadio() {
int testNum = this.testNum;
int promoteNum = this.promoteNum;

try{
double num = (float)promoteNum / testNum;//这里不加float结果就为0

DecimalFormat df = new DecimalFormat("0.00");//格式化小数
String s = df.format(num);//返回的是String类型

return Double.parseDouble(s)*100;
}catch (Exception e){
return 0;
}
}