我无法自定义例外。 请帮我

Question

When I try and make a catch statement using InvalidTestScore exception java won't allow me. However when I use IllegalArgumentException, java does allow me to make it.

// George Beazer

public class TestScores2 {
    public TestScores2(int[] arg) {
        System.out.println(average(arg));
    }
    public int average(int[]arg)
    {
        int temp=0;
        for (int i = 0; i < arg.length; i++) {
            if(arg[i]<0 || arg[i]>100)
            {
                IllegalArgumentException e = new IllegalArgumentException();
                throw e;
            }
            else
            {
                temp+=arg[i];
            }
        }
        return temp/arg.length;
    }
    public static void main(String[] args) {
        int []ar={4,78,33,89};
        TestScores2 ts=new TestScores2(ar);
    }

}

Runs fine

However if i run

public class TestScores2 {
    public TestScores2(int[] arg) {
        System.out.println(average(arg));
    }
    public int average(int[]arg)
    {
        int temp=0;
        for (int i = 0; i < arg.length; i++) {
            if(arg[i]<0 || arg[i]>100)
            {
                InvalidTestScoreException e = new InvalidTestScore();
                throw e;
            }
            else
            {
                temp+=arg[i];
            }
        }
        return temp/arg.length;
    }
    public static void main(String[] args) {
        int []ar={4,78,33,89};
        TestScores2 ts=new TestScores2(ar);
    }

}

I get can't find symbol. What does it take to make your own custom exception .

Answer 1

InvalidTestScoreException e = new InvalidTestScore();

??? shouldn't that be:

InvalidTestScoreException e = new InvalidTestScoreException();

Answer 2

As @Falmarri pointed out, you need to declare an InvalidTestScoreException class

Here is what a revised version might look like:

public class TestScores2 {

    public class InvalidTestScoreException extends RuntimeException {
        //Constructors go here
    }

    public TestScores2(int[] arg) {
        System.out.println(average(arg));
    }
    public int average(int[]arg)
    {
        int temp=0;
        for (int i = 0; i < arg.length; i++) {
            if(arg[i]<0 || arg[i]>100)
            {
                InvalidTestScoreException e = new InvalidTestScoreException();
                throw e;
            }
            else
            {
                temp+=arg[i];
            }
        }
        return temp/arg.length;
    }
    public static void main(String[] args) {
        int []ar={4,78,33,89};
        TestScores2 ts=new TestScores2(ar);
    }

}