public class NameSystem1 {

    public List BMoreToA(String[] a, String[] b) {
        List temp = new ArrayList();
        for (int i = 0; i < b.length; i++) {
            boolean flag = false;
            for (int j = 0; j < a.length; j++) {
                if (b[i].equals(a[j])) {
                    flag = true;
                    break;
                } else {
                    flag = false;
                }
            }
            if (!flag) {
                temp.add(b[i]);
            }
        }
        return temp;
    }

    public static void main(String[] args) {
        NameSystem1 test = new NameSystem1();

        String[] a = { "x", "y", "xy", "yx" };

        String[] b = { "xy", "y", "yx", "a", "b" };
        List temp = null;
        temp = test.BMoreToA(a, b);
        System.out.println("B比A多的字符串");
        for (int i = 0; i < temp.size(); i++) {
            System.out.print(temp.get(i) + "   ");
        }
        System.out.println("");
        System.out.println("B比A少的字符串");
        temp = test.BMoreToA(b, a);
        for (int i = 0; i < temp.size(); i++) {
            System.out.print(temp.get(i) + "   ");
        }
    }
}

------解决方案--------------------
Java code

import java.util.List;
import java.util.ArrayList;
import java.util.Iterator;

/**
 * Author: db2admin
 * Date  : 2010-2-4
 * Time  : 15:41:37
 * Comment:
 */

public class test {

    public static List toArrayList(String[] temp) {
        List templist=new ArrayList();
        for (int i = 0; i < temp.length; i++) {
            templist.add(temp[i]);
        }
        return templist;
    }

    public static List romove(List lista,List listb){
        lista.removeAll(listb);
        return lista;
        //System.out.println(lista);
    }

    public static List compareArr(String[] a,String[] b){
        List commonlist=new ArrayList();
        if(a.length<b.length){
            for(int i=0;i<a.length;i++){
                if(a[i].equals(b[i]))
                    commonlist.add(a[i]);
            }
        }
        return commonlist;
    }
    public static void main(String[] args){
        String[] a = {"x", "y", "xy", "yx"};
        String[] b = {"xy", "y", "yx", "a", "b"};
        //  A-B
        System.out.println(test.romove(test.toArrayList(a),test.toArrayList(b)));
        //  B-A
        System.out.println(test.romove(test.toArrayList(b),test.toArrayList(a)));
        //  A-(A-B) 公共集
        System.out.println(
                test.romove(test.toArrayList(a),test.romove(test.toArrayList(a),test.toArrayList(b)))
        );
        // 公共集-顺序值相同集
        System.out.println(
                test.romove(
                        test.romove(test.toArrayList(a),test.romove(test.toArrayList(a),test.toArrayList(b))),
                        test.compareArr(a,b))
        );
    }
}