[OCAJP][OCPJP]私有方法

public class TestA extends Root {

    public static void main(String[] args) {
        Root r = new TestA();
        System.out.println(r.method1()); // line n1
        System.out.println(r.method2()); // line n2
    }
}

class Root {

    private static final int MAX = 20000;

    private int method1() {
        int a = 100 + MAX;  // line n3
        return a;
    }

    protected int method2() {
        int a = 200 + MAX;  // line n4
        return a;
    }
}

Which line causes a compilation error?

A. Line n1
B. Line n2
C. Line n3
D. Line n4

題解

line n1會編譯錯誤，因為「method1」方法是Root類別的私有成員，無法由外面的類別存取。