看看Java的练习题

这两个Java题目求解，做的练习题谢谢！过程越简单越好，设计一个教师类teacher，私有成员变量为：id（编号，string），name（姓名，string）

public class Teacher {
    private String id;
    private String name;
    private int num;
    Teacher(){
        this.id = "000";
        this.name = "无名氏";
        this.num = 0;
    }
    Teacher(String id, String name, int num){
        this.id = id;
        this.name = name;
        this.num = num;
    }

    public String getId() {
        return id;
    }

    public void setId(String id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

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

    public int getNum() {
        return num;
    }

    public void setNum(int num) {
        this.num = num;
    }

    public void showinfo() {
        System.out.println("编号：" + id + "姓名：" + name + "课时：" + num);
    }
}