Question

I have a class A with a variable bool var = true and a getter method getVar(). I m trying to create a class B that extends A and redefines var to bool var = false. The code:

public class A{
    protected boolean var = true;
    public boolean getVar(){
        return var;
    }
}

public class B extends A{
    protected boolean var = false;
}

问题是,如果我执行:

B b_class = new B();
System.out.println(b_class.getVar());

I obtain true and I don t undestand why. What I m doing wrong?

Answer 1

You shouldn t be creating a new instance variable in your overridden class, because it can t be seen by the super class (A), and therefore when getVar() is called, it will return the value it can see. You should instead be setting the value of var in the constructor to be what you want.

public B() {
    var = false;
}

Answer 2

页: 1 仅躲藏在<代码>A.var上,但仅限于<代码>。 B。您是getVar(), 一种载于A的方法,见A.var, 即true。

Answer 3

您在<代码>B上宣布了一个新的<代码>var<>/code>领域,该代码为<代码>A.var。相反:

public class B extends A {
    public B() {
        var = false;
    }
}

Answer 4

在超级类别中,可以选择的变数不能改变。你们已经宣布保护养羊人。因此,无论你在延长级别上做什么,都永远表明你是真实的。

Answer 5

在B等地,GetVar是甲型六氯环己烷的产物,在甲型六氯环己烷确实如此。

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