Question

打印Inet4Address变量时没什么问题。

我得到了一个＆＃39;运算符+未定义参数类型字符串，void＆＃39;异常。

我将在班上展示一部分：

public class Command{
    private Inet4Address A;
    public Inet4Address getA(){
     return A;
 }
 public void showConf(){
     System.out.println("Interface A: IP: " + getA().getHostAddress()); // there is a problem
  }
}

任何简单的解决方案？

Answer 1

null hade a constructor作为回报，尝试创建Inet4Address并初始化public class Command{ private String url = "google.com"; private Inet4Address A = null; public Command() { super(); try { A = (Inet4Address) Inet4Address.getByName(url); } catch (UnknownHostException e) { // TODO Auto-generated catch block e.printStackTrace(); } } public static void main(String[] args) { new Command().showConf(); } public Inet4Address getA(){ return A; } public void showConf(){ System.out.println("Interface A: IP: " + getA().getHostAddress()); } }来解决此问题：

  Interface A: IP: 64.15.126.118

输出：

CREATE TABLE user (
    username text,
    password text,
    email text,
    company text,
    PRIMARY KEY (username)
);

打印Inet4Address错误

1 个答案: