java全排列寫法

public class Main {
      public static void print(int arr[],int n){
    	   for(int i=0;i<n;i++){
    		   System.out.print(arr[i]+" ");
    	   }
    	   System.out.println(arr[n]);
      }
      public static void swap(int arr[],int i,int p){
    	  int t=arr[i];
    	  arr[i]=arr[p];
    	  arr[p]=t;
      }
	  public static void allSort(int arr[],int p,int q){
		    if(p==q){
		    	 print(arr,q);
		    }
		    else{
		    	for(int i=p;i<=q;i++){
		    		swap(arr,i,p);
		    		allSort(arr,p+1,q);
		    		swap(arr,i,p);
		    	}
		    }
	  }
      public static void main(String[] args) {
		  int arr[]={1,2,3};
		  allSort(arr,0,arr.length-1);
	}
}