尝试…catch块未定义变量

Question

I have a program, which takes a parameter from the args[] array, defined in the main method, but has a backup in case that isn't defined, in the form of a try...catch block, which, if an ArrayIndexOutOfBounds exception is thrown, instead uses a method called getInt to prompt the user to enter a variable. But, for some reason, when I try to use that variable, my compiler says that it cannot find it. I have the following code:

try {
    int limit = Integer.parseInt(args[0]);
}
catch(ArrayIndexOutOfBoundsException e) {
    int limit = getInt("Limit? ");
}
int[] p = getPrimes(limit);

getPrimes is another method I have, which returns an array of prime numbers starting from 2 and up to a specified number (using the Sieve of Atkin). Anyway, when I write int[] p = getPrimes(limit); and try compiling, it says that the "limit" variable is not defined. Help please!

Answer 1

You should declare it outside the block:

int limit;
try {
    limit = Integer.parseInt(stuff[0]);
}
catch(ArrayIndexOutOfBoundsException e) {
    limit = getInt("Limit? ");
}
int[] p = getPrimes(limit);

Answer 2

在catch块之外声明limit ，当前在catch块catch{}的范围内

Answer 3

int limit;
try {
    limit = Integer.parseInt(stuff[0]);
}
catch(ArrayIndexOutOfBoundsException e) {
    limit = getInt("Limit? ");
}
int[] p = getPrimes(limit);

In your program you have created 2 local Limit variable one in try block and another in catch block.

Declare it outside the try block

Answer 4

Define limit variable outside of try/catch block, you do not have access to variables defined inside try block outside. You would also have to initialize it if you are calling it outside of try block as in your case here.