找不到符号IllegalArgumentException

Question

I have a very simple program that tries to throw an exception. The compiler says it cannot find IllegalArgumentException even though it didm't say anything about that name when I put it in the throw specifier part:

import java.lang.*;

class A
{
    public A() throws IllegalArgumentException
    {
        if (n <= 0)
            throw IllegalArgumentException("n is less than 0");
    }
}

Here's the error:

Main.java:28: error: cannot find symbol
            throw IllegalArgumentException("n is less than 0");
                  ^
  symbol:   method IllegalArgumentException(String)
  location: class A
1 error

I realize this is very simple (my very first attempt at writing Java). I've tried looking for answers but they haven't helped me to a solution.

Answer 1

Use the new keyword

public A() {
    int n = ...;
    if (n <= 0) {
        throw new IllegalArgumentException("n is less than 0");
    }
}