尝试对 args.length 和 op.length 使用 try catch

Question

我正在为如何使我的程序捕获 args 和 op 长度的语法而苦苦挣扎。我需要它们都正好是 3（3 个参数和 op 必须是 3 个字符），如果不是，我需要它来打印出相应的 println 消息。我是 Java 新手，所以如果我的代码看起来不愉快或严重错误，我深表歉意。

    import java.util.*;

public class dd{
public static void main(String[] args)
{   
    if (args.length !=3)
    if (op.length !=3)
    {
        try
        {
            int = args.length ;
            System.out.println("ok");
    }
    catch(ArrayIndexOutOfBoundsException e)
    {
            System.out.println("invalid number of arguments");
    }
    catch( NumberFormatException e )
    {
            System.out.println("invalid number of characters in operator");
    }
    finally
    {

    }

    String op = args[2];
        int op1 = Integer.parseInt(args[0]);
        int op2 = Integer.parseInt(args[1]);
        switch(op) {
          case "add":
            System.out.println(op1+op2);
            break;
          case "sub":
            System.out.println(op1-op2);
            break;



        } 
    }
    }

编辑：我通过简单的 if 语句让程序按需要运行。我现在的问题是如何使用 try catch 使程序功能相同？下面是新代码

    import java.util.*;

public class tester{
public static void main(String[] args)
{   
    if (args.length != 3 ){
    System.out.println ("Invalid argument");
}
    String op = args[2];
    int op1 = Integer.parseInt(args[0]);
    int op2 = Integer.parseInt(args[1]);
{ 
    if (op.length() !=3){
    System.out.println ("Invalid op length"); 
}
    switch(op) {
        case "add":
            System.out.println(op1+op2);
            break;
         case "sub":
            System.out.println(op1-op2);
            break;

    } 
 }
}
}

Answer 1

我不确定我是否完全理解你，但试试这个：

    public static void main(String[] args)
{   
    String op,args1;    //you need to declare the variables as string
    //you cant use the name args so i changed it to args1
    Scanner s = new Scanner(System.in);
    op = s.nextLine();  //get the input from the user and put it in op
    args1 = s.nextLine();  //get the input from the user and put it in args1
    if (args1.length() == 3 && op.length() == 3)       //You need to use .length() to get the string length
    {
        System.out.println("\"args1\" length and \"op\" length is 3 !");
    }
    else
    {
        System.out.println("one of the variables \"args1\" or \"op\" or both of them is'nt = 3");
    }
}