处理Java异常

Question

I can't figure out why my code isn't compiling correctly.. I can go through the code till it gets to the catch block. It works, displaying the message, so I know it's catching the error. However, it ends my program saying I have that same error at the same place. I can't see what I am doing wrong. Thanks for any help!!

class Verification {

String detAccess(String[] pL, String[] uL, String pass, String user) {
    int pos = 0;
    String access = "";
    try {
        for (int i=0; !user.equals(uL[i]); i++)
            pos++;
    } catch (ArrayIndexOutOfBoundsException exec) {
        System.out.println("Username doesn't exist.");
        throw exec;
    }
    if(pass.equals(pL[pos])) {
        access = "MEMBER";
    } else {
        System.out.println("Incorrect password.");
        access = "DENIED";
    }

    return access;        
}

}

Answer 1

您要抛出异常的throw exec ；

Answer 2

You're rethrowing the exception.

Another thing:

if(pass.equals(pL[pos])) {
    access = "MEMBER";

That will cause the exception to come up again even if you didn't rethrow it as it'll try to check the password list with a nonexistent index.

Answer 3

You should rewrite your code to something like this:

int pos = -1;
...
for (int i=0;uL.length; i++)
{
    if(user.equals(uL[i])) { pos=i; break; }
}
...
if(pos==-1)
{
    // user not found
} else {
    // test the pass with pos as index
}

Answer 4

you are throwing the exception back up. the point of handling the exception is that it wron't carry on.

Answer 5

Two problems:

1. You're catching and rethrowing the exception; if you "handle it", you don't need to rethrow it.

2. You're using "Exception Handling" to manage the "normal control flow" through your program. This is generally considered "bad style". Can you not control your iteration, and determine that "you're done" by looking something else?

   UPDATE: ie nio's example

Answer 6

The code is compiling correctly if you're able to run it. As for the program ending in error, that's because you're throwing an exception:

throw exec;

You successfully caught the exception, but then you threw it again. If nothing else catches it, the program will terminate in an error.