Java链式写法，子类继承父类的属性，也可以返回子类的对象，只是需要重写基类的Set方法

public class MyLS {        public static void main(String[] args) {        // TODO Auto-generated method stub        System.out.println(new Student().setName("1").setAge(21).toString());                System.out.println(new NAN().setName("2").setAge(20).setSex('男').toString());                System.out.println(new NV().setName("3").setAge(22).setSex('女').toString());            }}class Student{        private String name;        private Integer age;    public String getName() {        return name;    }    public Student setName(String name) {        this.name = name;        return this;    }    public Integer getAge() {        return age;    }    public Student setAge(Integer age) {        this.age = age;        return this;    }    @Override    public String toString() {        return "Student [name=" + name + ", age=" + age + ", getName()=" + getName() + ", getAge()=" + getAge() + "]";    }    }class NAN extends Student{        private Character sex='男';    public Character getSex() {        return sex;    }    public NAN setSex(Character sex) {        this.sex = sex;        return this;    }        @Override    public NAN setName(String name) {         super.setName(name);         return this;    }        @Override    public NAN setAge(Integer age) {        // TODO Auto-generated method stub        super.setAge(age);        return this;    }    @Override    public String toString() {        return "NAN [sex=" + sex + ", getSex()=" + getSex() + ", getName()=" + getName() + ", getAge()=" + getAge()                + "]";    }        }class NV extends Student{        private Character sex='女';    public Character getSex() {        return sex;    }    public NV setSex(Character sex) {        this.sex = sex;        return this;    }        @Override    public NV setName(String name) {         super.setName(name);         return this;    }        @Override    public NV setAge(Integer age) {        // TODO Auto-generated method stub        super.setAge(age);        return this;    }    @Override    public String toString() {        return "NV [sex=" + sex + ", getSex()=" + getSex() + ", getName()=" + getName() + ", getAge()=" + getAge()                + "]";    }    }