我正在使用java 8并使用lambda函数。我有一个嵌套对象列表，每个对象main包含相同对象的列表，可以转到n级。只是想知道我们是否可以使用lambda函数或Stream API来获取特定属性的总和（sumofhead在下面），取决于对象中的一个特定键（如果操作是真的），然后遍历它的子节点（并找到sum），直到孩子们空。
以下是我收到的json
[{
"mainheadname": "Assets",
"sumofhead": 120.0000,
"id": 102,
"children": [{
"mainheadname": "Cash",
"sumofhead": 9900.0000,
"id": 107,
"children": [{
"mainheadname": "Cash Counter1",
"sumofhead": 17662.2100,
"id": 153,
"children": [{
"mainheadname": "CashCounterChild",
"sumofhead": 0.0,
"id": 1179,
"children": [{
"mainheadname": "Name New",
"sumofhead": -10.0000,
"id": 1242,
"children": [{
"mainheadname": "Name New Child",
"sumofhead": 0.0,
"id": 1247,
"children": [{
"mainheadname": "Nec Chil d",
"sumofhead": 0.0,
"id": 1248,
"children": [{
"mainheadname": "NEChild",
"sumofhead": 0.0,
"id": 1249,
"children": [],
"coacode": "CC12000",
"defuldledgertype": 1,
"current": null,
"operational": "True"
}],
"coacode": "rt120",
"defuldledgertype": 1,
"current": "False",
"operational": "True"
}],
"coacode": "dd22",
"defuldledgertype": 1,
"current": null,
"operational": "True"
}],
"coacode": "12000",
"defuldledgertype": 1,
"current": null,
"operational": null
}, {
"mainheadname": "New 1",
"sumofhead": 0.0,
"id": 1246,
"children": [],
"coacode": "C678",
"defuldledgertype": 1,
"current": null,
"operational": "True"
}],
"coacode": "ChildCC",
"defuldledgertype": 1,
"current": null,
"operational": "True"
}, {
"mainheadname": "CashCounterChild1",
"sumofhead": 0.0,
"id": 1245,
"children": [],
"coacode": "C120",
"defuldledgertype": 1,
"current": null,
"operational": "True"
}],
"coacode": "CC122",
"defuldledgertype": 1,
"current": "True",
"operational": null
}, {
"mainheadname": "Cash CounterOne",
"sumofhead": 37211.6000,
"id": 158,
"children": [{
"mainheadname": "New",
"sumofhead": 0.0,
"id": 1243,
"children": [{
"mainheadname": "New Child Name",
"sumofhead": 0.0,
"id": 1244,
"children": [],
"coacode": "AC120",
"defuldledgertype": 2,
"current": null,
"operational": "True"
}],
"coacode": "c120",
"defuldledgertype": 1,
"current": "False",
"operational": "True"
}],
"coacode": "CCCCC",
"defuldledgertype": 1,
"current": "True",
"operational": null
}, {
"mainheadname": "Ne Test Cash Counter",
"sumofhead": -1060.0000,
"id": 1159,
"children": [],
"coacode": "1200",
"defuldledgertype": 1,
"current": null,
"operational": "True"
}, {
"mainheadname": "New Counter test",
"sumofhead": 0.0,
"id": 1162,
"children": [],
"coacode": "CCode",
"defuldledgertype": 1,
"current": null,
"operational": null
}, {
"mainheadname": "New Thing Test",
"sumofhead": 10.0000,
"id": 1163,
"children": [],
"coacode": "COde",
"defuldledgertype": 1,
"current": "False",
"operational": "False"
}, {
"mainheadname": "Evening Counter",
"sumofhead": 0.0,
"id": 1176,
"children": [],
"coacode": "EC",
"defuldledgertype": 1,
"current": null,
"operational": "True"
}, {
"mainheadname": "Morning Counter",
"sumofhead": 0.0,
"id": 1177,
"children": [],
"coacode": "zyz",
"defuldledgertype": 1,
"current": null,
"operational": "True"
}, {
"mainheadname": "Cash Operations",
"sumofhead": 0.0,
"id": 1376,
"children": [],
"coacode": "120",
"defuldledgertype": 1,
"current": "True",
"operational": null
}],
"coacode": "CA",
"defuldledgertype": 1,
"current": "true",
"operational": null
}, {
"mainheadname": "Receivable",
"sumofhead": 0.0,
"id": 108,
"children": [{
"mainheadname": "Babar",
"sumofhead": 5310.7200,
"id": 154,
"children": [],
"coacode": "Babar cus",
"defuldledgertype": 1,
"current": "True",
"operational": null
}],
"coacode": "RE",
"defuldledgertype": 1,
"current": "true",
"operational": null
}, {
"mainheadname": "Inventory",
"sumofhead": 107804.6000,
"id": 110,
"children": [],
"coacode": "INV",
"defuldledgertype": 1,
"current": "true",
"operational": null
}, {
"mainheadname": "Bank Transaction",
"sumofhead": 0.0,
"id": 111,
"children": [{
"mainheadname": "MCB bankacount",
"sumofhead": -3071.8000,
"id": 1253,
"children": [],
"coacode": "bmcb",
"defuldledgertype": 1,
"current": "True",
"operational": null
}],
"coacode": "BAN",
"defuldledgertype": 1,
"current": "true",
"operational": null
}, {
"mainheadname": "Accumulated Depreciation",
"sumofhead": 0.0,
"id": 119,
"children": [],
"coacode": "ACDEP",
"defuldledgertype": 2,
"current": "false",
"operational": null
}],
"coacode": "A1",
"defuldledgertype": 1,
"current": null,
"operational": null
}, {
"mainheadname": "Liabilities",
"sumofhead": 0.0,
"id": 103,
"children": [{
"mainheadname": "Payable",
"sumofhead": 0.0,
"id": 109,
"children": [{
"mainheadname": "Employee Salary Account",
"sumofhead": 0.0,
"id": 113,
"children": [{
"mainheadname": "RehanAbbas",
"sumofhead": 0.0,
"id": 122,
"children": [],
"coacode": "Rehan emp",
"defuldledgertype": 2,
"current": "True",
"operational": null
}, {
"mainheadname": "Ehtesham",
"sumofhead": 0.0,
"id": 1180,
"children": [],
"coacode": "Ehtesham emp",
"defuldledgertype": 2,
"current": "True",
"operational": null
}],
"coacode": "EMP",
"defuldledgertype": 2,
"current": "true",
"operational": null
}, {
"mainheadname": "Shoaib",
"sumofhead": -22850.0000,
"id": 124,
"children": [],
"coacode": "Shoaib Ven",
"defuldledgertype": 2,
"current": "True",
"operational": null
}, {
"mainheadname": "Ahmad",
"sumofhead": 7020.0000,
"id": 1276,
"children": [],
"coacode": "Ahmad Ven",
"defuldledgertype": 2,
"current": "True",
"operational": null
}, {
"mainheadname": "Abbasi",
"sumofhead": 0.0,
"id": 1383,
"children": [],
"coacode": "Abbasi Ven",
"defuldledgertype": 2,
"current": "True",
"operational": null
}, {
"mainheadname": "Abbasi",
"sumofhead": 26100.0000,
"id": 1384,
"children": [],
"coacode": "Abbasi Ven",
"defuldledgertype": 2,
"current": "True",
"operational": null
}],
"coacode": "Pay",
"defuldledgertype": 2,
"current": "true",
"operational": null
}, {
"mainheadname": "Paid up Capital",
"sumofhead": 0.0,
"id": 112,
"children": [],
"coacode": "PCAP",
"defuldledgertype": 2,
"current": "false",
"operational": null
}],
"coacode": "L1",
"defuldledgertype": 2,
"current": null,
"operational": null
}, {
"mainheadname": "Expense",
"sumofhead": 0.0,
"id": 104,
"children": [{
"mainheadname": "Discount given",
"sumofhead": 3320.4000,
"id": 115,
"children": [],
"coacode": "DISE",
"defuldledgertype": 2,
"current": null,
"operational": "true"
}, {
"mainheadname": "Depreciation",
"sumofhead": 0.0,
"id": 118,
"children": [{
"mainheadname": "Depreciation Computer",
"sumofhead": 0.0,
"id": 1157,
"children": [],
"coacode": "DC",
"defuldledgertype": 1,
"current": null,
"operational": null
}],
"coacode": "Depreciation",
"defuldledgertype": 1,
"current": null,
"operational": "false"
}, {
"mainheadname": "Cost of Goods",
"sumofhead": 143719.8600,
"id": 120,
"children": [],
"coacode": "COG",
"defuldledgertype": 1,
"current": null,
"operational": "true"
}, {
"mainheadname": "Services sold",
"sumofhead": 0.0,
"id": 121,
"children": [],
"coacode": "SS",
"defuldledgertype": 1,
"current": null,
"operational": "true"
}],
"coacode": "EX1",
"defuldledgertype": 1,
"current": null,
"operational": null
}, {
"mainheadname": "Income",
"sumofhead": 0.0,
"id": 105,
"children": [{
"mainheadname": "discount received",
"sumofhead": 0.0,
"id": 114,
"children": [],
"coacode": "DISI",
"defuldledgertype": 2,
"current": null,
"operational": "true"
}, {
"mainheadname": "Sale of Product",
"sumofhead": -207183.1300,
"id": 116,
"children": [],
"coacode": "IIS",
"defuldledgertype": 1,
"current": null,
"operational": "true"
}, {
"mainheadname": "Income from Services",
"sumofhead": 0.0,
"id": 117,
"children": [],
"coacode": "IDS",
"defuldledgertype": 2,
"current": null,
"operational": "true"
}],
"coacode": "INC",
"defuldledgertype": 2,
"current": null,
"operational": null
}, {
"mainheadname": "GST",
"sumofhead": -139164.4600,
"id": 106,
"children": [],
"coacode": "GST",
"defuldledgertype": 0,
"current": null,
"operational": null
}]
我上面的Java对象如下：
package com.sabre.rest.models;
import java.util.List;
public class COALedga {
private List<COALedga> children;
private String coacode;
private int defuldledgertype;
private int id;
private String mainheadname;
private String operational;
private int sumofhead;
public COALedger() {
// TODO Auto-generated constructor stub
}
public List<COALedga> getChildren() {
return this.children;
}
public void setChildern(List<COALedga> children) {
this.children = children;
}
public String getCoacode() {
return coacode;
}
public void setCoacode(String coacode) {
this.coacode = coacode;
}
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String isOperational() {
return operational;
}
public void setOperational(String operational) {
this.operational = operational;
}
public int getDefuldledgertype() {
return defuldledgertype;
}
public void setDefuldledgertype(int defuldledgertype) {
this.defuldledgertype = defuldledgertype;
}
public String getMainHeadName() {
return mainHeadName;
}
public void setMainHeadName(String mainHeadName) {
this.mainHeadName = mainHeadName;
}
public int getSumOfHead() {
return sumOfHead;
}
public void setSumOfHead(int sumOfHead) {
this.sumOfHead = sumOfHead;
}
}
答案 0 :(得分：4)
不确定
int sum(COALedga c) {
return c.getSumOfHead() + c.getChildren().stream().mapToInt(child -> sum(child)).sum();
}