Java 遍历列表并将项目添加到另一个列表
我在列表中得到了如下数据:Java 遍历列表并将项目添加到另一个列表,java,Java,我在列表中得到了如下数据: groupCode | groupMember ------------------------------- 001 | name1 ------------------------------- 001 | name2 ------------------------------- 002 | name3 ------------------------------- 003
groupCode | groupMember
-------------------------------
001 | name1
-------------------------------
001 | name2
-------------------------------
002 | name3
-------------------------------
003 | name4
在某些组中,我可以有更多的组成员。所以我需要遍历列表,并以这种方式对数据进行排序:
001 (List)
- name1 (List inside List)
- name2
002 (List)
- name3
- name4
我使用组和组成员类。我该怎么做
public class Group {
private String groupCode;
private GroupMember groupMember;
。。。我不能使用私有列表groupMember代码>这里
public class GroupMember {
private String name;
public String getName() {
return name;
}
如果成员
为原始待处理列表,其内容如下:
Group [001, GroupMember [name1]]
Group [001, GroupMember [name2]]
Group [002, GroupMember [name3]]
Group [003, GroupMember [name4]]
可通过以下代码实现:
class GroupMember {
private String name;
public GroupMember(String name) {
super();
this.name = name;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
@Override
public String toString() {
return String.format("GroupMember [%s]", getName());
}
}
class Group {
private String groupCode;
private GroupMember groupMember;
public Group(String groupCode, GroupMember groupMember) {
super();
this.groupCode = groupCode;
this.groupMember = groupMember;
}
public String getGroupCode() {
return groupCode;
}
public void setGroupCode(String groupCode) {
this.groupCode = groupCode;
}
public GroupMember getGroupMember() {
return groupMember;
}
public void setGroupMember(GroupMember groupMember) {
this.groupMember = groupMember;
}
@Override
public String toString() {
return String.format("Group [%s, %s]", getGroupCode(), getGroupMember());
}
}
...
List<Group> members = new ArrayList<>();
members.add(new Group("001", new GroupMember("name1")));
members.add(new Group("001", new GroupMember("name2")));
members.add(new Group("002", new GroupMember("name3")));
members.add(new Group("003", new GroupMember("name4")));
根据需要。使用groupingBy
?如果我理解正确,您的List
具有重复的groupCode
,并且您希望将其过滤到List
,对吗?这与复合设计模式有一定关系吗?
import static java.util.stream.Collectors.*;
...
Map<String, List<GroupMember>> grouped = members
.stream()
.collect(groupingBy(Group::getGroupCode,
mapping(Group::getGroupMember, toList())));
{001=[GroupMember [name1], GroupMember [name2]], 002=[GroupMember [name3]], 003=[GroupMember [name4]]}