英文:
Java Enum Accepted Values
问题
一个枚举数据类型被定义为类的属性。
public class Foo {
public enum Direction {
NORTH("north"),
EAST("east"),
SOUTH("south");
public final String label;
private Direction(String label) {
this.label = label;
}
}
private Direction direction;
...
}
当我解析 JSON 数据以匹配这个类时，我遇到了一个错误
字符串 "east"：不是枚举类接受的值之一：[NORTH、EAST、SOUTH、WEST]
通过将枚举数据全部更改为小写，可以解决这个问题。如果我想使用 Java 枚举数据类型的约定，需要什么来解决这个问题？
英文:
An enum data type is defined as an attribute of a class.
public class Foo {
public enum Direction {
NORTH("north"),
EAST("east"),
SOUTH("south");
public final String label;
private Direction(String label) {
this.label = label;
}
}
private Directory direction;
...
}
When I parse a Json data to match the class, I get an error
String "east": not one of the values accepted for Enum class: [NORTH, EAST, SOUTH, WEST]
This problem can be resolved by changing the enum data to all low case. If I want to use the Java enum data type convention, what is needed to resolve the problem?
答案1
得分: 4
如果您正在使用Jackson来反序列化Foo类，您可以：
public class Foo {
public enum Direction {
NORTH("north"),
EAST("east"),
SOUTH("south");
@JsonValue
public final String label;
private Direction(String label) {
this.label = label;
}
}
private Direction direction;
// 必须存在direction的getter和setter方法
}
// 然后通过以下方式进行反序列化：
ObjectMapper mapper = new ObjectMapper();
String json = "{\"direction\":\"north\"}";
Foo f = mapper.readValue(json, Foo.class);
这将导致一个带有Direction.NORTH字段的Foo对象。
有关在使用Jackson时的其他可能性，请查看 https://www.baeldung.com/jackson-serialize-enums。
英文:
If you are using Jackson to deserialise the Foo class, you could:
public class Foo {
public enum Direction {
NORTH("north"),
EAST("east"),
SOUTH("south");
@JsonValue
public final String label;
private Direction(String label) {
this.label = label;
}
}
private Direction direction;
// getter, setter for direction must exist
}
// then deserialise by:
ObjectMapper mapper = new ObjectMapper();
String json = "{\"direction\":\"north\"}";
Foo f = mapper.readValue(json, Foo.class);
This will result in a Foo object with a Direction.NORTH field.
For other possibilities when using Jackson check https://www.baeldung.com/jackson-serialize-enums
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