检查一个类对象是否是 Java 中另一个类对象的子类 [英] Check if a Class Object is subclass of another Class Object in Java

问题描述

我正在尝试使用 Java 的反射 API 并尝试处理一些字段.现在我坚持要确定我的字段的类型.字符串很简单，只需执行myField.getType().equals(String.class).这同样适用于其他非派生类.但是如何检查派生类呢?例如.LinkedList 作为 List 的子类.我找不到任何 isSubclassOf(...) 或 extends(...) 方法.我是否需要遍历所有 getSuperClass() 并自己找到我的超类?

I'm playing around with Java's reflection API and trying to handle some fields. Now I'm stuck with identifying the type of my fields. Strings are easy, just do myField.getType().equals(String.class). The same applies for other non-derived classes. But how do I check derived classes? E.g. LinkedList as subclass of List. I can't find any isSubclassOf(...) or extends(...) method. Do I need to walk through all getSuperClass() and find my supeclass by my own?

推荐答案

你想要这个方法:

boolean isList = List.class.isAssignableFrom(myClass);

一般情况下，List(上面)应该替换为 superclass，myClass 应该替换为 subclass>

where in general, List (above) should be replaced with superclass and myClass should be replaced with subclass

来自 JavaDoc:

确定此 Class 对象表示的类或接口是否与指定的 Class 对象表示的类或接口相同，或者是其超类或超接口> 参数.如果是，则返回 true；否则返回false.如果这个 Class 对象表示一个原始类型，如果指定的 Class 参数正是这个 Class，则此方法返回 true目的;否则返回false.

Determines if the class or interface represented by this Class object is either the same as, or is a superclass or superinterface of, the class or interface represented by the specified Class parameter. It returns true if so; otherwise it returns false. If this Class object represents a primitive type, this method returns true if the specified Class parameter is exactly this Class object; otherwise it returns false.

参考:

• Class.isAssignableFrom(Class)

相关:

a) 检查对象是否是您在编译时知道的类或接口(包括子类)的实例:

a) Check if an Object is an instance of a Class or Interface (including subclasses) you know at compile time:

boolean isInstance = someObject instanceof SomeTypeOrInterface;

示例:

assertTrue(Arrays.asList("a", "b", "c") instanceof List<?>);

b) 检查对象是否是您只在运行时知道的类或接口(包括子类)的实例:

b) Check if an Object is an instance of a Class or Interface (including subclasses) you only know at runtime:

Class<?> typeOrInterface = // acquire class somehow
boolean isInstance = typeOrInterface.isInstance(someObject);

示例:

public boolean checkForType(Object candidate, Class<?> type){
    return type.isInstance(candidate);
}

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