从零自学Java-8.创建第一个对象

Posted on 2018-03-19 19:47  夜逆尘  阅读(260)  评论(2)  编辑  收藏  举报

1.创建对象；
2.使用属性描述对象；
3.确定对象的行为；
4.合并对象；
5.从其他对象继承；
6.转换对象和其他类型的信息。

 

程序NewRoot2：计算输入数的算数平方根并输出

 1 package com.jsample;
 2 
 3 public class NewRoot2 {
 4     public static void main(String[] args){
 5         int number = 100;
 6         if (args.length > 0){
 7             number = Integer.parseInt(args[0]);
 8         }
 9         System.out.println("The square root of "
10                 + number
11                 + " is "
12                 + Math.sqrt(number)
13         );
14     }
View Code

 

输出：

The square root of 169 is 13.0

 

程序ModemTester：测试下属四个class的功能

 1 package com.jsample;
 2 
 3 public class ModemTester {
 4     public static void main(String[] args){
 5         CableModem surfBoard = new CableModem();
 6         DslModem gateway = new DslModem();
 7         AcousticModem acoustic = new AcousticModem();
 8         surfBoard.speed = 500000;
 9         gateway.speed = 400000;
10         acoustic.speed = 300;
11         System.out.println("Trying the cable modem:");
12         surfBoard.displaySpeed();
13         surfBoard.connect();
14         System.out.println("Trying the DSL modem");
15         gateway.displaySpeed();
16         gateway.connect();
17         System.out.println("Trying the acoustic modem");
18         acoustic.displaySpeed();
19         acoustic.connect();
20         System.out.println("Closing all modems");
21         surfBoard.disconnect();
22         gateway.disconnect();
23         acoustic.disconnect();
24     }
25 }
View Code

下属class：Modem

 1 package com.jsample;
 2 
 3 public class Modem {
 4     int speed;
 5 
 6     public void displaySpeed(){
 7         System.out.println("Speed: " + speed);
 8     }
 9 
10     public void disconnect(){
11         System.out.println("Disconnecting to the Internet");
12     }
13 }
View Code

 

下属class：CableModem

 1 package com.jsample;
 2 
 3 public class CableModem extends Modem{
 4     String method = "cable connecttion";
 5 
 6     public void connect(){
 7         System.out.println("Connecting to the Internet");
 8         System.out.println("Using a " + method);
 9     }
10 }
View Code

 

下属class：DslModem

 1 package com.jsample;
 2 
 3 public class DslModem extends Modem{
 4     String method = "DSL phone connection";
 5 
 6     public void connect(){
 7         System.out.println("Connecting to the Internet");
 8         System.out.println("Using a " + method);
 9     }
10 }
View Code

 

下属class：AcousticModem

 1 package com.jsample;
 2 
 3 public class AcousticModem extends Modem{
 4     String method = "acoustic connection";
 5 
 6     public void connect(){
 7         System.out.println("Connecting to the Internet");
 8         System.out.println("Using a " + method);
 9     }
10 }
View Code

 

输出：
Trying the cable modem:
Speed: 500000
Connecting to the Internet
Using a cable connecttion
Trying the DSL modem
Speed: 400000
Connecting to the Internet
Using a DSL phone connection
Trying the acoustic modem
Speed: 300
Connecting to the Internet
Using a acoustic connection
Closing all modems
Disconnecting to the Internet
Disconnecting to the Internet
Disconnecting to the Internet