Codigo erroneo parte V

public class doom2

{

public static void main(String args[])

{

int a [] = new int[4];

int b [] = new int[4];

a[0]=18;a[1]=15;a[2]=31;a[3]=2;

for (int i = 0; i < a.length; i ++)

{

b = a;
	for (int j =  + 1; j < b.length; j ++)
	 {
	 
 	  if(a[i] > b[j])
 	   {
 	    int z = a[i];
 	    b[j] = a[i];
 	    b[j]= z;
 	   }
      for (int r = 0; r < b.length; r ++)
      {
      System.out.println(a[r]);	
     }
  }
 	}
 	 
}