public class Student {
    private int id;
    private String name;
    private int score;

    public Student copy() {
        Student std = new Student();
        std.id = this.id;
        std.name = this.name;
        std.score = this.score;
        return std;
    }
}

在copy()中，为什么std变量还能调用id，name，score属性，std.id，std.name....呢？这个属性不是private吗？