使用父方法访问子类变量

class ParentClass {
    protected int variable;

    public void setVariable(int value) {
        this.variable = value;
    }

    public int getVariable() {
        return this.variable;
    }
}

class ChildClass extends ParentClass {
    private int childVariable;

    public void setChildVariable(int value) {
        this.childVariable = value;
    }

    public int getChildVariable() {
        return this.childVariable;
    }
}

public class Main {
    public static void main(String[] args) {
        ChildClass child = new ChildClass();
        child.setVariable(10);
        child.setChildVariable(20);

        System.out.println("Parent variable: " + child.getVariable());
        System.out.println("Child variable: " + child.getChildVariable());
    }
}