概况表：
目录结构为：我们在com.java17包下创建了两个class：Demo01、Demo02。
举例一：
Demo01:
package com.java17;
public class Demo01 {
private String name = "haohao";
public static void main(String[] args) {
Demo01 java = new Demo01();
System.out.println(java.name);
}
}
//Demo01运行成功输出 haohao
Demo02:
package com.java17;
public class Demo02 {
public static void main(String[] args) {
Demo01 java = new Demo01();
System.out.println(java.name);
}
}
//Demo02运行失败不能输出 haohao
举例二：
//Demo02调用Demo01的方法：
Demo01:
package com.java17;
public class Demo01 {
private String name;
private int age;
public void setname(String name) {
this.name = name;
}
public String getname() {
return this.name;
}
public void setage(int age) {
this.age = age;
}
public int getage() {
return this.age;
}
public static void main(String[] args) {
Demo01 java = new Demo01();
System.out.println(java.name);
}
}
Demo02:
package com.java17;
public class Demo02 {
public static void main(String[] args) {
Demo01 java = new Demo01();
java.setname("浩浩");
java.setage(18);
System.out.println("名字是：" + java.getname());
System.out.println("年龄为：" + java.getage());
}
}
举例三：
// import 的使用
package com.java17;
import java.util.Scanner; //通过import 引入了Scanner 包
public class Demo02 {
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in); //Scanner 实例化
}
}