char array sort in upper case and lower case

import java.util.*;

public class Main {
    public static void main(String[] args) {
      
      char a[]={'a','b','A','B','c','D'};
      int i=0;
      int j=a.length-1;
      while(i<j){
        if(a[i]>=65 && a[i]<=90){
          i++;
        } if(a[j]>=97 && a[j]<=122){
          j--;
        } if((a[j]>=65 && a[j]<=90) && (a[i]>=97 && a[i]<=122)){
          char temp=a[i];
          a[i]=a[j];
          a[j]=temp;
          i++;
          j--;
        }
        
      }
      System.out.println(Arrays.toString(a));
  }
}