英文:
Collect values from List of objects to Map
问题
我有一个类：
class Employee {
private Integer id;
private String name;
//getters/setters
}
同时，我有一个包含员工的ArrayList：
List<Employee> employees = new ArrayList<>();
如何使用流提取id作为键，name作为值，放入HashMap中？
map.put(employee.getId(), employee.getName());
更新
如果我的字段中有自定义的列表呢？
class Employee {
private List<Filter> filters;
private String name;
//getters/setters
}
class Filter {
String name;
String keyword;
//getters/setters
}
我想将Filter中的name作为值，keyword作为键放入映射中。
英文:
I have class:
class Employee {
private Integer id;
private String name;
//getters/setters
}
Also I've an Arraylist with employees:
List<Employee> employees = new Arraylist<>();
How can I extract id as a key and name as a value to HashMap (with streams)?
map.put(employee.getId(), employee.getName())
UPDATED
What if I've a custom Lists as fields?
class Employee {
private List<Filters> filters;
private String name;
//getters/setters
}
class Filter {
String name;
String keyword;
//getters/setters
}
And I want to put name (from Filter) as a value, and keyword as a key to map.
答案1
得分: 1
你可以使用流将其转换如下：
public Map<Integer, String> convertListToMap(List<Employee> list) {
Map<Integer, String> map = list.stream()
.collect(Collectors.toMap(Employee::getId, Employee::getName));
return map;
}
英文:
You can convert using streams as below:
public Map<Integer, String> convertListToMap(List<Employee> list) {
Map<Integer, String> map = list.stream()
.collect(Collectors.toMap(Employee::getId, Employee:: getName));
return map;
}
答案2
得分: -2
<!-- begin snippet: js hide: false console: true babel: false -->
<!-- language: lang-html -->
Map<String,String> map=Maps.newHashMap();
employees.stream().forEach(->{
map.put(i.getId,i.getName);
});
<!-- end snippet -->
英文:
<!-- begin snippet: js hide: false console: true babel: false -->
<!-- language: lang-html -->
Map<String,String> map=Maps.newHashMap();
employees.stream().forEach(->{
map.put(i.getId,i.getName);
});
<!-- end snippet -->
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