把二维字符串数组的前2列相同的合并，后2列相应的值相加

package com.uniclick.dap;

import java.util.HashSet;
import java.util.Iterator;
import java.util.Set;

public class TestDoubleArray {

	/**
	 * @function 此类的功能是把二维字符串数组的前2列相同的合并，后2列相应的值相加
	 * @author [email protected]
	 * @time 2013-02-24
	 * @param args
	 */
	public static void main(String[] args) {
		String[][] arr = {
				{"新浪","学生","10","5"},
				{"网易","学生","9","4"},
				{"新浪","白领","8","3"},
				{"新浪","学生","15","2"},
				{"网易","白领","19","7"},
				{"百度","白领","20","5"},
				{"新浪","学生","4","1"},
				{"新浪","白领","1","1"},
				{"网易","学生","9","4"},
				{"网易","学生","9","4"},
				{"网易","学生","5","5"},
		};
		
		//add to set
		Set<String> set = new HashSet<String>();
		for(int i=0;i<arr.length;i++){
			set.add(arr[i][0]+"\t"+arr[i][1]);
		}
		
		//此二维数组用来装结果
		String[][] result = new String[set.size()][4];
//		Object[][] result = new Object[set.size()][4];
		//
		Iterator<String> itr = set.iterator();
		int r = 0;
		while(itr.hasNext()){
			String mark = itr.next();
			//如果没有初始化，就赋值为0，免得null报错
			int res2 = Integer.valueOf(result[r][2]==null?"0":result[r][2]);
			int res3 = Integer.valueOf(result[r][3]==null?"0":result[r][3]);
			for(int i=0;i<arr.length;i++){
				if(mark.equalsIgnoreCase(arr[i][0]+"\t"+arr[i][1])){
					result[r][0]=arr[i][0];
					result[r][1]=arr[i][1];
					res2 += Integer.valueOf(arr[i][2]);
					res3 += Integer.valueOf(arr[i][3]);
				}
				result[r][2]=Integer.toString(res2);
				result[r][3]=Integer.toString(res3);
			}
			r++;
		}
		
		//print result array
		for(int i=0;i<result.length;i++){
			System.out.println(result[i][0]+":"+result[i][1]+":"+result[i][2]+":"+result[i][3]);
		}

	}

}

console print：

新浪:白领:9:4
新浪:学生:29:8
百度:白领:20:5
网易:白领:19:7
网易:学生:32:17

PS:这个问题困扰了我几天了，绞尽脑汁才把这功能实现，不知还有没有更好的方法实现。工期紧，留待以后再优化。