java - 如何连接具有相同键属性的对象列表

Question

如果对象的特定关键属性匹配，我正在尝试连接自定义对象

我正在获取以下格式的数据。

List is like this.

 Data[
{batchNo: "1212", location: "12bbn", qty: "123", rawMaterialId: "6743"},
{batchNo: "1213", location: "12nmn", qty: "300", rawMaterialId: "6743"},
{batchNo: "1241", location: "vbv2", qty: "123", rawMaterialId: "9179"},
{batchNo: "1251", location: "fdsfds", qty: "244", rawMaterialId: "9179"},
{batchNo: "1233", location: "cvcvbc", qty: "200", rawMaterialId: "9169"},
{batchNo: "1266", location: "bnbn", qty: "600", rawMaterialId: "9935"}
]

我正在尝试根据特定的关键属性(即( rawMaterialId )连接它们。

例如，如果 rawMaterialId=6743 of index[0] 与 index[1] 匹配，则两者都需要连接。

Expected List

    Data[
      {batchNo: "1212 , 1213", location: "12bbn , 12nmn", qty: "123 , 300", rawMaterialId: "6743"},
{batchNo: "1241,1251", location: "vbv2 , fdsfds", qty: "123,244",rawMaterialId: "9179"},
{batchNo: "1233", location: "cvcvbc", qty: "200", rawMaterialId:"9169"},
{batchNo: "1266", location: "bnbn", qty: "600", rawMaterialId: "9935"}
   ]

我试过使用 For 循环但没有得到预期的输出

Code which I tried

       for(int i=0; i<data.length;i++)
        {
         for(int j=0; i<data.length;i++)
          {
            if(data[i].rawMaterialId == data[j].rawMaterialId )
            {
                data[i].location=data[i].location +","+ data[j].location;
                data[i].batchNo=data[i].batchNo +"," + data[j].batchNo;
                data[i].quantity=data[i].quantity +"," + data[j].quantity;
            }
        } 
}

请帮我解决这个问题，欢迎任何建议和更正。提前致谢。

Answer 1

如果您有数组数据，您可以使用stream api 来转换它。最后一行将 Data 替换为您项目的真实类型。

data = Arrays.stream(data).       // Create stream from your array
    collect(Collectors.toMap(     // Transform it to Map
        d -> d.rawMaterialId,     // It is keys of creating map
        d -> d,                   // This is values of creating map 
        (d1, d2) -> {             // Function for merging values with same keys. 
                                  // There happens all neded concatenations.
            d1.location = d1.location + "," + d2.location;
            d1.batchNo = d1.batchNo + "," + d2.batchNo;
            d1.quantity = d1.quantity + "," + d2.quantity;
            return d1;
        }).
    values().toArray(new Data[0]); // Transform map to new array. 
                                   // Replace Data to real type of your items.