Protected members in a superclass inaccessible by indirect subclass in Java

社会主义新天地 提交于 2019-12-05 21:26:02

Perhaps you're a little confused.

Here's my quick demo and shows an indirect subclass accessing a protected attribute:

// A.java
package a;
public class A {
    protected int a;
}

// B.java 
package b;   //<-- intermediate subclass
import a.A;
public class B extends A {
}

// C.java
package c; //<-- different package 
import b.B;
public class C extends B  { // <-- C is an indirect sub class of A 
    void testIt(){
        a++;
        System.out.println( this.a );//<-- Inherited from class A
    }
    public static void main( String [] args ) {
        C c = new C();
        c.testIt();
    }
}

it prints 1

As you see, the attribute a is accessible from subclass C.

If you show us the code you're trying we can figure out where your confusion is.

Maybe the problem is that he try to access the protected field of other instance but not his. such like:

package a;
public class A{
    protected int a;
}

package b;
public class B extends A{

}

package c;
public class C extends B{
    public void accessField(){
        A ancient = new A();
        ancient.a = 2;  //That wouldn't work.

        a = 2;   //That works.
    }


}
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