import java.util.ArrayList;
import java.util.Random;
public class Permutation
{
public Permutation(int x)
{
size = x;
}
public Permutation getNumber()
{
ArrayList<Integer> empty=new ArrayList<Integer>();
for(int i=1; i<=size; i++)
empty.add(i);
ArrayList<Integer> full=new ArrayList<Integer>();
for(int j=0; j<size; j++)
{
int num=generator.nextInt(empty.size());
full.add(empty.get(num));
empty.remove(num);
}
return full; //error is here, my compiler says incompatible types
}
private int size;
private Random generator = new Random();
}
Refactorings
No refactoring yet !
Ants
November 7, 2009, November 07, 2009 04:11, permalink
1 rating.
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Well... line 11 says you are returning an object that is a Permutation, but in line 27 you are returning full, which is an ArrayList<Integer> based on line 17.
ravi-gill.myopenid.com
October 21, 2010, October 21, 2010 15:44, permalink
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import java.util.ArrayList;
import java.util.Random;
public class Permutation{
private int size;
private Random generator = new Random();
public static void main(String[] args){
Permutation p = new Permutation(10);
ArrayList<Integer> mutations = p.getNumber();
for(Integer i:mutations){
System.out.println(i);
}
}
public Permutation(int x){
size = x;
}
public ArrayList<Integer> getNumber(){
ArrayList<Integer> empty=new ArrayList<Integer>();
for(int i=1; i<=size; i++)
empty.add(i);
ArrayList<Integer> full=new ArrayList<Integer>();
for(int j=0; j<size; j++){
int num=generator.nextInt(empty.size());
full.add(empty.get(num));
empty.remove(num);
}
return full;
}
}
Alright, so for out class, we have to write a program that produces random permutations of the numbers 1-10. To do this, our teacher wants us to make two arrays, one with the numbers 1-10. Then pick one of those numbers at random, remove it, and append it to the second array. We need to implement a class called Permutation to do this. I figured out the code, but there is a small error in it which I don't understand. If anyone can help me, I'd appreciate it! Thanks! Code is below and I point out the error in comment.