Java：获取类中的所有变量名
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Java: get all variable names in a class
提问by ufk
I have a class and I want to find all of its public fields(not methods). How can I do this?
我有一个类，我想找到它的所有公共字段（不是方法）。我怎样才能做到这一点？
Thanks!
谢谢！
采纳答案by Bozho
Field[] fields = YourClassName.class.getFields();
returns an array of all public variables of the class.
返回类的所有公共变量的数组。
getFields()return the fields in the whole class-heirarcy. If you want to have the fields defined only in the class in question, and not its superclasses, use getDeclaredFields(), and filter the publicones with the following Modifierapproach:
getFields()返回整个类继承中的字段。如果您只想在相关类中定义字段，而不是在其超类中定义字段，请使用getDeclaredFields()并public通过以下Modifier方法过滤这些字段：
Modifier.isPublic(field.getModifiers());
The YourClassName.classliteral actually represents an object of type java.lang.Class. Check its docs for more interesting reflection methods.
的YourClassName.class字面实际上代表类型的对象java.lang.Class。检查其文档以获取更有趣的反射方法。
The Fieldclass above is java.lang.reflect.Field. You may take a look at the whole java.lang.reflectpackage.
Field上面的类是java.lang.reflect.Field. 你可以看看整个java.lang.reflect包。
回答by cellepo
https://docs.oracle.com/javase/tutorial/reflect/class/classMembers.htmlalso has charts for locating methods and constructors.
https://docs.oracle.com/javase/tutorial/reflect/class/classMembers.html也有用于定位方法和构造函数的图表。
回答by Amit Kaneria
As mentioned by few users, below code can help find all the fields in a given class.
正如少数用户所提到的，下面的代码可以帮助查找给定类中的所有字段。
TestClass testObject= new TestClass().getClass();
Method[] methods = testObject.getMethods();
for (Method method:methods)
{
String name=method.getName();
if(name.startsWith("get"))
{
System.out.println(name.substring(3));
}else if(name.startsWith("is"))
{
System.out.println(name.substring(2));
}
}
However a more interesting approach is below:
然而，更有趣的方法如下：
With the help of Hymanson library, I was able to find all class properties of type String/integer/double, and respective values in a Map class. (without using reflections api!)
在 Hymanson 库的帮助下，我能够找到 String/integer/double 类型的所有类属性，以及 Map 类中的相应值。（不使用反射 api！）
TestClass testObject = new TestClass();
com.fasterxml.Hymanson.databind.ObjectMapper m = new com.fasterxml.Hymanson.databind.ObjectMapper();
Map<String,Object> props = m.convertValue(testObject, Map.class);
for(Map.Entry<String, Object> entry : props.entrySet()){
if(entry.getValue() instanceof String || entry.getValue() instanceof Integer || entry.getValue() instanceof Double){
System.out.println(entry.getKey() + "-->" + entry.getValue());
}
}
回答by Sahil Chhabra
You can use any of the two based on your need:
您可以根据需要使用两者中的任何一个：
Field[] fields = ClassName.class.getFields(); // returns inherited members but not private members.
Field[] fields = ClassName.class.getDeclaredFields(); // returns all members including private members but not inherited members.
To filter only the public fields from the above list (based on requirement) use below code:
要仅过滤上述列表中的公共字段（根据要求），请使用以下代码：
List<Field> fieldList = Arrays.asList(fields).stream().filter(field -> Modifier.isPublic(field.getModifiers())).collect(
Collectors.toList());
