Java 访问抽象实例变量
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Java Access Abstract Instance variables
提问by B T
I have an abstract classwith a variable like follows:
我有一个abstract class像下面这样的变量：
public abstract class MyAbstractClass {
int myVariable = 1;
protected abstract void FunctionThatUsesMyVariable();
}
Then when I go to instantiate my classthrough the following code, myVariablecannot be seen:
然后当我class通过下面的代码去实例化我的时候，myVariable是看不到的：
MyAbstractClass myClass = new MyAbstractClass() {
@Override
protected void FunctionThatUsesMyVariable() {
// TODO Auto-generated method stub
}
};
What am I doing wrong and how can I achieve what I am trying to achieve?
我做错了什么，我怎样才能实现我想要实现的目标？
回答by dcernahoschi
You are declaring myVariableas having package access and your 2 classes reside in different packages. Thus the variable is not visible to inheriting classes. You can declare it with protectedaccess to be visible or put the 2 classes in the same package.
您声明myVariable具有包访问权限，并且您的 2 个类驻留在不同的包中。因此该变量对继承类不可见。您可以将其声明protected为可见或将 2 个类放在同一个包中。
public abstract class MyAbstractClass {
protected int myVariable = 1;
protected abstract void FunctionThatUsesMyVariable();
}
回答by OldCurmudgeon
Seems to work for me:
似乎对我有用：
public class Test {
public static abstract class MyAbstractClass {
int myVariable = 1;
protected abstract void FunctionThatUsesMyVariable();
}
public void test() {
MyAbstractClass myClass = new MyAbstractClass() {
@Override
protected void FunctionThatUsesMyVariable() {
myVariable = 2;
}
};
}
public static void main(String args[]) {
new Test().test();
}
}
I suspect you are declaring the two classes in different packages. If that is what you want then you should make the variable protected(or publicif you must). Alternatively - obviously - put them in the same package.
我怀疑您在不同的包中声明了这两个类。如果这是您想要的，那么您应该创建变量protected（或者public如果必须）。或者 - 显然 - 将它们放在同一个包中。
回答by neutrino
Declare your variable as protected. It's package-privateby default.
将您的变量声明为受保护的。这是package-private默认的。
回答by Kafkaesque
Because you're still subclassing/extending the abstract class and unless you make it protected, the field isn't inherited.
因为您仍在对抽象类进行子类化/扩展，除非您对其进行保护，否则该字段不会被继承。
