public Rectangle(double length, double width) {
conn = DriverManager.getConnection(sourceURL, info);
public static void main(String[] args) throws IOException {
System.out.println("异步任务执行完成");
1. 获取Class对象:使用实体类的类字面常量获取对应的Class对象/正版资料免费资料大全十点半。
public double getPerimeter() {
System.out.println("Drawing a circle with radius " + radius);