Java基础学习Day06-蒲公英云

Java基础学习Day06

知识点

数组的动态初始化问题
权限修饰符
this
构建类中方法快捷键

数组的动态初始化问题

public class Test {
    public static void main(String[] args) {
        int[] arr = new int[10];
        System.out.println(arr.length);
        System.out.println(arr[0]);
    }
}

结果是 10 0
说明动态初始化后数组就分配好长度和初始值了

权限修饰符

修饰符	同类	同包	外包子类	外包
private	√	×	×	×
default	√	√	×	×
protect	√	√	√	×
public	√	√	√	√

this

this可以调用本类中的方法和属性以及构造方法
调用无参构造方法时 this.类名()
调用带参构造方法时 this.类名(参数列表)

构建类中方法快捷键

Alt + Shift + S

课后作业

使用get set方法实例化3个学生

package com.day06;

public class Student {

private String name;
private int age;
private char sex;
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;
}
public char getSex() {
    return sex;
}
public void setSex(char sex) {
    this.sex = sex;
}

}

package com.day06;

public class Test {

public static void main(String[] args) {
    Student s1 = new Student();
    Student s2 = new Student();
    Student s3 = new Student();
    s1.setName("小明");
    s1.setAge(11);
    s1.setSex('男');
    s2.setName("小红");
    s2.setAge(10);
    s2.setSex('女');
    s3.setName("小华");
    s3.setAge(13);
    s3.setSex('男');
    System.out.println(s1.getName() + "\t" + s1.getSex() + "\t" + s1.getAge());
    System.out.println(s2.getName() + "\t" + s2.getSex() + "\t" + s2.getAge());
    System.out.println(s3.getName() + "\t" + s3.getSex() + "\t" + s3.getAge());
}