4. java面向对象——继承（extends）_课程思政java继承

java面向对象三大特征之继承

• 继承关系

• 练习案例代码

• 创建父类 Role

package Example.Extend;

public class Role {
    private String name;
    private int age;

    public Role() {
    }

    public Role(String name, int age) {
        this.name = name;
        this.age = age;
    }

    public void lookSchedule() {
        System.out.println("正在查看课表");
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }
}
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• 创建子类1 Student

package Example.Extend;

public class Student extends Role {
    private String classes;

    // 无参构造
    public Student() {
        /*
         * super();必须写在方法的第一行（不写也存在，系统默认给出）
         * 用于调用父类的无参构造
         */
        super();
    }

    /*
     * 调用父类中的有参构造方法（super必须手动给出）
     */
    public Student(String name, int age, String classes) {
        super(name, age);
        this.classes = classes;
    }

    public String getClasses() {
        return classes;
    }

    public void setClasses(String classes) {
        this.classes = classes;
    }

    public void reaction() {
        System.out.println("填写听课反馈");
    }

}

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• 创建子类2 Teacher()

package Example.Extend;

public class Teacher extends Role {
    private String department;

    /*
     * super();必须写在方法的第一行（不写也存在，系统默认给出）
     * 用于调用父类的无参构造
     * this作用：初始化默认值
     */
    public Teacher() {
        // 数据初始化
        this("思政处");
    }

    public Teacher(String department) {
        this.department = department;
    }

    public String getDepartment() {
        return department;
    }

    public void setDepartment(String department) {
        this.department = department;
    }

    public void issues() {
        System.out.println("发布问题");
    }

}

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• 创建测试类 EduTest

package Example.Extend;

public class EduTest {
    public static void main(String[] args) {
        // 利用父类中的有参构造器
        Student student = new Student("李华", 18, "2020级（1）班");
        System.out.println(student.getClasses() + "的" + student.getName() + "同学" + student.getAge() + "岁");
        student.lookSchedule();
        student.reaction();
        System.out.println("=========================================");
        // 不用父类有参构造器直接给出
        Teacher teacher = new Teacher();
        teacher.setName("李老师");
        teacher.setAge(28);
        // 不使用默认值
        teacher.setDepartment("教务处");
        System.out.println(teacher.getDepartment() + "的" + teacher.getName() + teacher.getAge() + "岁");
        teacher.lookSchedule();
        teacher.issues();
    }
}
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• 运行结果