Java by 8ラムダ式

私は会社のエンティティオブジェクトのリストを持っています。Java by 8ラムダ式

package com.raghu.example2; 
    public class CompanyEntity { 

     private String name; 

     private String locationName; 

     private String officeName; 

     private String buildingName; 


     public CompanyEntity(String name, String locationName, String officeName, String buildingName) { 
      super(); 
      this.name = name; 
      this.locationName = locationName; 
      this.officeName = officeName; 
      this.buildingName = buildingName; 
    //  System.out.println(this); 
     } 

     public String getName() { 
      return name; 
     } 

     public String getLocationName() { 
      return locationName; 
     } 

     public String getOfficeName() { 
      return officeName; 
     } 

     public String getBuildingName() { 
      return buildingName; 
     } 

     @Override 
     public String toString() { 
      StringBuilder builder = new StringBuilder(); 
      builder.append("CompanyEntity [name="); 
      builder.append(name); 
      builder.append(", locationName="); 
      builder.append(locationName); 
      builder.append(", officeName="); 
      builder.append(officeName); 
      builder.append(", buildingName="); 
      builder.append(buildingName); 
      builder.append("]"); 
      return builder.toString(); 
     } 
    }

エンティティのリストを会社オブジェクトに変換したいと考えています。会社オブジェクトは入れ子構造です。

パッケージcom.raghu.example2;

import java.util.List;

public class Company { 

    private String name; 

    private List<Location> locationList; 

    public Company(String name, List<Location> locationList) { 
     super(); 
     this.name = name; 
     this.locationList = locationList; 
    } 

    public String getName() { 
     return name; 
    } 


    public List<Location> getLocationList() { 
     return locationList; 
    } 

    @Override 
    public String toString() { 
     StringBuilder builder = new StringBuilder(); 
     builder.append("Company [name="); 
     builder.append(name); 
     builder.append(", locationList="); 
     builder.append(locationList); 
     builder.append("]"); 
     return builder.toString(); 
    } 
}

場所オブジェクト：

package com.raghu.example2; 

import java.util.List; 

public class Location { 

    private String locationName; 

    private List<Office> officeList; 

    public Location(String locationName, List<Office> officeList) { 
     super(); 
     this.locationName = locationName; 
     this.officeList = officeList; 
    } 

    public String getLocationName() { 
     return locationName; 
    } 

    public List<Office> getOfficeList() { 
     return officeList; 
    } 



    @Override 
    public int hashCode() { 
     final int prime = 31; 
     int result = 1; 
     result = prime * result + ((locationName == null) ? 0 : locationName.hashCode()); 
     result = prime * result + ((officeList == null) ? 0 : officeList.hashCode()); 
     return result; 
    } 

    @Override 
    public boolean equals(Object obj) { 
     if (this == obj) 
      return true; 
     if (obj == null) 
      return false; 
     if (getClass() != obj.getClass()) 
      return false; 
     Location other = (Location) obj; 
     if (locationName == null) { 
      if (other.locationName != null) 
       return false; 
     } else if (!locationName.equals(other.locationName)) 
      return false; 
     if (officeList == null) { 
      if (other.officeList != null) 
       return false; 
     } else if (!officeList.equals(other.officeList)) 
      return false; 
     return true; 
    } 

    @Override 
    public String toString() { 
     StringBuilder builder = new StringBuilder(); 
     builder.append("Location [locationName="); 
     builder.append(locationName); 
     builder.append(", officeList="); 
     builder.append(officeList); 
     builder.append("]\n"); 
     return builder.toString(); 
    } 



}

オフィス：

package com.raghu.example2; 

import java.util.List; 

public class Office { 

    private String name; 
    private List<Building> listOfBuilding; 

    public Office(String name, List<Building> listOfBuilding) { 
     super(); 
     this.name = name; 
     this.listOfBuilding = listOfBuilding; 
    } 

    public String getName() { 
     return name; 
    } 

    public List<Building> getListOfBuilding() { 
     return listOfBuilding; 
    } 

    @Override 
    public String toString() { 
     StringBuilder builder = new StringBuilder(); 
     builder.append("\n"); 
     builder.append("Office [name="); 
     builder.append(name); 
     builder.append(", listOfBuilding="); 
     builder.append(listOfBuilding); 
     builder.append("]"); 
     return builder.toString(); 
    } 



}

ビル：会社エンティティの

package com.raghu.example2; 

public class Building { 

    private String name; 

    private String address; 

    public Building(String name, String address) { 
     super(); 
     this.name = name; 
     this.address = address; 
    } 

    public String getName() { 
     return name; 
    } 

    public String getAddress() { 
     return address; 
    } 



    @Override 
    public int hashCode() { 
     final int prime = 31; 
     int result = 1; 
     result = prime * result + ((address == null) ? 0 : address.hashCode()); 
     result = prime * result + ((name == null) ? 0 : name.hashCode()); 
     return result; 
    } 

    @Override 
    public boolean equals(Object obj) { 
     if (this == obj) 
      return true; 
     if (obj == null) 
      return false; 
     if (getClass() != obj.getClass()) 
      return false; 
     Building other = (Building) obj; 
     if (address == null) { 
      if (other.address != null) 
       return false; 
     } else if (!address.equals(other.address)) 
      return false; 
     if (name == null) { 
      if (other.name != null) 
       return false; 
     } else if (!name.equals(other.name)) 
      return false; 
     return true; 
    } 

    @Override 
    public String toString() { 
     StringBuilder builder = new StringBuilder(); 
     builder.append("Building [name="); 
     builder.append(name); 
     builder.append(", address="); 
     builder.append(address); 
     builder.append("]"); 
     return builder.toString(); 
    } 
}

一覧：

[ 
CompanyEntity 
[name=Mannar&Co, locationName=CHENNAI, officeName=sub-urban, buildingName=sez1], CompanyEntity 
[name=Mannar&Co, locationName=CHENNAI, officeName=sub-urban, buildingName=sez2], CompanyEntity 
[name=Mannar&Co, locationName=CHENNAI, officeName=urban, buildingName=sez10], CompanyEntity 
[name=Mannar&Co, locationName=CHENNAI, officeName=urban, buildingName=sez11], CompanyEntity 
[name=Mannar&Co, locationName=BANGALORE, officeName=sub-urban, buildingName=sez1], 
CompanyEntity 
[name=Mannar&Co, locationName=BANGALORE, officeName=sub-urban, buildingName=sez2], 
CompanyEntity [name=Mannar&Co, locationName=BANGALORE, officeName=urban, buildingName=sez10], 
CompanyEntity 
[name=Mannar&Co, locationName=BANGALORE, officeName=urban, buildingName=sez11]]

完全に8つのオブジェクトがあります。私は場所、オフィス、ビルごとにグループ化したいと思った。

私は以下のような構造が欲しい。

Company [name=Mannar&Co, 
locationList= 
[Location [locationName=CHENNAI, 
    officeList=[ 
      Office [name=sub-urban, 
       listOfBuilding= 
         [Building [name=sez1, address=sholinganallur], 
         Building [name=sez2, address=navallur]]], 
      Office [name=urban, 
       listOfBuilding= 
         [Building [name=sez10, address=t-nagar], 
         Building [name=sez11, address=velacherry]]]]] 
, Location [locationName=BANGALORE, 
    officeList=[ 
       Office [name=sub-urban, 
         listOfBuilding= 
         [Building [name=sez1, address=sarjapur], Building [name=sez2, address=marathahalli]]], 
Office [name=urban, listOfBuilding=[Building [name=sez10, address=m.g.road], Building [name=sez11, address=c.v.raman nagar]]]]] 
]]

私はjava 8 group by clauseを使いたいと思います。

私がこれまで試してみました：グループのすべての場所

Map<String,List<CompanyEntity>> map1 = 
    listOfCompanies.stream().collect(Collectors.groupingBy(CompanyEntity::getLocationName)); 
map1.forEach((k,v)->System.out.println("\n"+ k + " Group BY " + v + "\n"));

グループのすべてのオフィス：

Map<String,List<CompanyEntity>> map2 =listOfCompanies.stream().collect(Collectors.groupingBy(CompanyEntity::getOfficeName)); 
map2.forEach((k,v)->System.out.println("\n"+ k + " Group BY " + v + "\n"));

を複数のレベルのグループ化を行うと、ネストされたオブジェクトを取得する方法は？

出典

2017-05-27 Raghu

あなたはこのような何かを行うことができます。

Map<String, Map<String, Map<String, List<String>>>> map = list.stream() 
      .collect(Collectors.groupingBy(CompanyEntity::getName, 
        Collectors.groupingBy(CompanyEntity::getLocationName, 
        Collectors.groupingBy(CompanyEntity::getOfficeName, 
          Collectors.mapping(CompanyEntity::getBuildingName, Collectors.toCollection(ArrayList::new))))));

地図出力：

{Mannar&Co={CHENNAI={urban=[sez10, sez11], sub-urban=[sez1, sez2]}, BANGALORE={urban=[sez10, sez11], sub-urban=[sez1, sez1]}}}

は、その後、そのマップから

出典

2017-05-27 07:24:35 ing8ar

'Collectors.toCollection（ArrayListのを::新）会社のオブジェクトを塗りつぶす'ことができます – Andrew

@AndrewTobilko *現在の実装では、一般的に** no **です。 – Eugene

@Eugene、なぜそれは一般的に使用できないのですか？ – Andrew

答えて

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