java将所有接口读入列表

Question

如何将所有TaskStatusConstant接口项自动转换为一个List<String>

public interface TaskStatusConstant {

    final static String NEW = "New";
    final static String ACCEPTED = "Accepted";
    final static String REJECTED = "Rejected";
    final static String REASSIGNED = "Reassigned";
    final static String COMPLETED = "Completed";

}

Answer 1

public enum TaskStatusConstant2 {
       NEW("New"), ACCEPTED("Accepted"), REJECTED("Rejected"), REASSIGNED("Reassigned"), COMPLETED("Completed");

       private String value;

       private TaskStatusConstant2(String value) {
          this.value = value;
       }
       public String getStatus() {
          return value;
       }
}

刚刚试过这个。。。不确定这是否适用于我的其他代码：）

Answer 2

可以使用反射，例如：

    List<String> constants = new ArrayList<String>();
    Field[] fields = TaskStatusConstant.class.getFields();
    for (Field field : fields) {
        if (field.getType().equals(String.class)) {
            constants.add(field.getName());
        }
    }
    for (String constant : constants) {
        System.out.println(constant);
    }

Answer 3

使用enum（推荐，有很多好处）

public enum TaskStatusConstant {
           NEW("New"),
      ACCEPTED("Accepted"),
      REJECTED("Rejected"),
    REASSIGNED("Reassigned"),
     COMPLETED("Completed");

    private final String toString;

    private TaskStatusConstant(String toString) {
        this.toString = toString;
    }

    @Override
    public String toString() {
        return toString;
    }

    public static List<String> valuesAsString() {
        List<String> list = new ArrayList<String>();
        for(TaskStatusConstant c : values()) {
            list.add(c.toString());
        }

        return list;
    }
}

使用反射（不推荐，这很麻烦，有时是必要的）

public static List<String> valuesAsString()
throws IllegalAccessException {
    List<String> list = new ArrayList<String>();
    for(Field f : TaskStatusConstant.class.getDeclaredFields()) {
        if(f.getType() == String.class) {
            f.setAccessible(true);
            list.add((String)f.get(null));
        }
    }

    return list;
}

Answer 4

这些信息应以enumeration格式表示

public enum TaskStatusConstant {
   NEW,
   ACCEPTED,
   REJECTED,
   REASSIGNED,
   COMPLETED
}

要在Java中迭代枚举，请使用以下命令：

for (TaskStatusConstant task: TaskStatusConstant.values()) {
  // do what you want
}