Map<Long,String>map=userList.stream().collect(Collectors.toMap(User::getId,User::getName)); 这个获取的就是key为id,value为name的map了。 2. 三个参数的用法 还是沿用上面那个例子,如果这个时候你想获取key是age,value是name的map呢?如果你还是沿用上面的方法,就会出问题了,因为有两个age...
Map<String, WorkstationCenter> centerMap = workstationCenterList.stream().collect(Collectors.toMap(WorkstationCenter::getCenterId, WorkstationCenter ->WorkstationCenter));//Map<String, List<WorkstationCenter>> listMap =workstationCenters.stream().collect(Collectors.groupingBy(WorkstationCenter::getGroup...
publicvoidfilterEmployeesThenGroupByStream(){Map<String,List<Employee>>resultMap=getAllEmployees().stream().filter(employee->"上海公司".equals(employee.getSubCompany())).collect(Collectors.groupingBy(Employee::getDepartment));System.out.println(resultMap);} 两种写法都可以得到相同的结果: 代码语言:javascri...
// 按照年龄分组 Map<Integer, List<User>> map = users.stream().collect(Collectors.groupingBy(User::getAge)); System.out.println(map); // { // 20=[ // User{id=1, name='Tom', age=20}, // User{id=3, name='Steve', age=20} // ], // 30=[ // User{id=2, name='Jack',...
Map<String,Long> map = items.stream().collect(Collectors.groupingBy(t->t,Collectors.counting())); System.out.println(JSON.toJSONString(map)); } 输出结果:{"papaya":1,"orange":1,"banana":2,"apple":3} 2、 在实际需求中,我们可能需要对一组对象进行分组,而且分组的条件有多个。比如对国家和...
Map<Integer, List<String>> employeeNamesByAge = employees.stream() .collect(Collectors.groupingBy( Employee::getAge, Collectors.mapping(Employee::getName, Collectors.toList()) ) ); Employee::getAge— age 属性 getter 方法作为方法参数 [Function] ...
问在Java stream中使用collectors.groupingBy修改返回的Map值类型EN有时候需要获取对象的属性值，属性少的话...
(); map3.put("id", 1); map3.put("name", "Charlie"); list.add(map3); // 使用groupingBy根据id进行分组 Map<Integer, List<Map<String, Object>>> groupedMap = list.stream() .collect(Collectors.groupingBy( item -> (Integer) item.get("id"), Collectors.to...
JDK8使用Stream的把List使用流式Stream转成LinkedHashMap Map<Integer, List<TbmFactorConfig>> tbmFactorConfigMap = tbmFactorConfigList.stream().collect(Collectors.groupingBy(TbmFactorConfig::getFactorValue, LinkedHashMap::new, Collectors.toList())); ...
String studentsName = students.stream().map(student -> student.getName()).collect(Collectors.joining()); System.out.println(studentsName); String studentsName2 = students.stream().map(student -> student.getName()).collect(Collectors.joining(",")); ...