求助了，代码遇到了问题，排序算法达不到排序效果

public class SortSelectionAlgorithm {

	
	public static <T extends Comparable<T>> T[] sortSelection(T arr[]){
       if(arr!=null &&arr.length>0){
    	   int n = arr.length;
    	   for (int i = 0; i < n; i++) {
    		   int minIndex = i;
    		   for(int j = i+1;j<n;j++){
    			   if(arr[j].compareTo(arr[minIndex])<0){//则证明arrj<arrminindex
    				   minIndex = j;
    				
    			   }
    			   swapArr(arr, minIndex, j);
    		   }
		}
       }		
		return arr;
	}
	private static <T> void swapArr(T arr[],int aIndex,int bIndex){
		T temp = null;
		temp = arr[aIndex];
		arr[aIndex] = arr[bIndex];
		arr[bIndex] = temp;
	}
	public static void main(String[] args) {
	/*	Integer a[] = {10,9,8,7,6,5,4,3,2,1};
		sortSelection(a);
		for (Integer integer : a) {
			System.out.println(integer);
		}*/
		/* Student[] d = new Student[4];
	        d[0] = new Student("A",95);
	        d[1] = new Student("B",95);
	        d[2] = new Student("D",90);
	        d[3] = new Student("E",91);
	        sortSelection(d);
			for (Student student : d) {
				System.out.println(student.toString());
			}*/
		SortObject a[] = {new SortObject("A",9),new SortObject("B",9),new SortObject("C",8),new SortObject("E",8),new SortObject("D",6),new SortObject("F",5),new SortObject("G",4),new SortObject("H",3),new SortObject("I",2),new SortObject("J",1)};
		sortSelection(a);
		for (SortObject sortObject : a) {
			System.out.println(sortObject.toString());
		}
		
	}
}
public class SortObject implements Comparable<SortObject> {

	private String userName;
	private int age;

	public SortObject() {
		super();
		// TODO Auto-generated constructor stub
	}

	public SortObject(String userName, int age) {
		super();
		this.userName = userName;
		this.age = age;
	}

	public String getUserName() {
		return userName;
	}

	public void setUserName(String userName) {
		this.userName = userName;
	}

	public int getAge() {
		return age;
	}

	public void setAge(int age) {
		this.age = age;
	}

	@Override
	public String toString() {
		return "SortObject [userName=" + userName + ", age=" + age + "]";
	}

	@Override

	public int compareTo(SortObject o) {
		// TODO Auto-generated method stub
		int result;
		System.out.println("this.userName== " + this.userName + ",o.userName== " + o.userName);
		if (this.age != o.age) {
			result = this.age - o.age;
			return result;
		} else {
			// this:arr[j] < o:arr[minIndex]result<0
			if (!this.userName.equals(o.getUserName())) {
				result = this.userName.compareTo(o.userName);// this>o
				System.out.println("result=== " + result);
				return result;
			} else {
				return 0;
			}
		}

	}

}

没找到哪里写的有问题，简单数组排序可实现，类排序 SortObject 在 age 相同，name 不同的时候排序不对，求解答