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This code generates all permutations of the numbers 0, 1, 2,...., n-1. I am trying to get it to use recursion to do this. I am not compiling. I do not show errors, but I am not getting it to work. Can anyone see where I am going wrong?

```
import java.io.*;
public class NumberPermutationIterator {
public NumberPermutationIterator(int n)
{
a = new int[n];
boolean done = false;
for (int i = 0; i < n; i++) a[i] = i;
}
public int[] nextPermutation()
{
if (a.length <= 1) return a;
for (int i = a.length - 1; i > 0; i--){
if (a[i -1] > a[i])
{
int j = a.length -1;
while (a[i-1] > a[j]) j--;
swap(i-1, j);
reverse(i, a.length -1);
return a;
}
}
return a;
}
public boolean hasMorePermutations()
{
if (a.length <= 1) return false;
for (int i = a.length -1; i > 0; i--)
{
if (a[i-1] < a[i]) return true;
}
return false;
}
public void swap (int i, int j)
{
int temp = a[i];
a[i] = a[j];
a[j] = temp;
}
public void reverse (int i, int j)
{
while (i < j) { swap (i, j); i++; j++;}
}
private int[] a;
public class Permutation {
public void main(String args[]) throws IOException {
int n = 3;
char[] a = new char[n];
for (int i = 0; i < n; i++) a[i] = Character.forDigit(i, 10);
permute("", new String(a));
}
public void permute(String beginningString, String endingString) {
if (endingString.length() <= 1)
System.out.println(beginningString + endingString);
else
for (int i = 0; i < endingString.length(); i++) {
try {
String newString = endingString.substring(0, i) + endingString.substring(i + 1);
permute(beginningString + endingString.charAt(i), newString);
} catch (StringIndexOutOfBoundsException exception) {
exception.printStackTrace();
}
}
}
}
}
```