20165334实验二 面向对象程序设计

20165334 实验二《Java面向对象程序设计》

实验内容

一、实现百分制成绩转成“优、良、中、及格、不及格”五级制成绩的功能

1、产品代码

public class MyUtil{
    public static String percentage2fivegrade(int grade){
        //如果成绩小于0，转成“错误”
        if ((grade < 0))
            return "错误";
            //如果成绩小于60，转成“不及格”
        else if (grade < 60)
            return "不及格";
            //如果成绩在60与70之间，转成“及格”
        else if (grade < 70)
            return "及格";
            //如果成绩在70与80之间，转成“中等”
        else if (grade < 80)
            return "中等";
            //如果成绩在80与90之间，转成“良好”
        else if (grade < 90)
            return "良好";
            //如果成绩在90与100之间，转成“优秀”
        else if (grade < 101)
            return "优秀";
            //如果成绩大于100，转成“错误”
        else
            return "错误";
    }
}

测试代码

import junit.framework.TestCase;
import org.junit.Test;

public class MyUtilTest extends TestCase {
    @Test
    public void testNormal() {
        assertEquals("不及格", MyUtil.percentage2fivegrade(55));
        assertEquals("及格", MyUtil.percentage2fivegrade(65));
        assertEquals("中等", MyUtil.percentage2fivegrade(75));
        assertEquals("良好", MyUtil.percentage2fivegrade(85));
        assertEquals("优秀", MyUtil.percentage2fivegrade(95));
    }
    @Test
    public void testExceptions() {
        assertEquals("错误", MyUtil.percentage2fivegrade(-50));
        assertEquals("错误", MyUtil.percentage2fivegrade(110));
    }
    @Test
    public void testBoundary() {
        assertEquals("不及格", MyUtil.percentage2fivegrade(0));
        assertEquals("及格", MyUtil.percentage2fivegrade(60));
        assertEquals("中等", MyUtil.percentage2fivegrade(70));
        assertEquals("良好", MyUtil.percentage2fivegrade(80));
        assertEquals("优秀", MyUtil.percentage2fivegrade(90));
        assertEquals("优秀", MyUtil.percentage2fivegrade(100));
    }

}

二、以TDD的方式研究学习StringBuffer

1、产品代码

public class StringBufferDemo {
  public static void main(String [] args){
                 StringBuffer buffer = new StringBuffer(20);
                 buffer.append('S');
                 buffer.append("tringBuffer");
                 System.out.println(buffer.charAt(1));
                 System.out.println(buffer.capacity());
                 System.out.println(buffer.indexOf("tring"));
                  System.out.println("buffer = " + buffer.toString());
                  System.out.println(buffer.length());
              }

}

测试代码

import junit.framework.TestCase;
import org.junit.Test;
public class StringBufferDemoTest extends TestCase {
    StringBuffer a=new StringBuffer("StringBuffer");
    StringBuffer b=new StringBuffer("StringBufferStringBuffer");
    StringBuffer c=new StringBuffer("StringBufferStringBufferStringBuffer");
    @Test
    public void testcharAt() throws Exception{
        assertEquals('S',a.charAt(0));
        assertEquals('g',a.charAt(5));
        assertEquals('r',a.charAt(11));
    }
    @Test
    public void testcapacity() throws Exception{
        assertEquals(28,a.capacity());
        assertEquals(40,b.capacity());
        assertEquals(52,c.capacity());
    }
    @Test
    public void testlength() throws Exception {
        assertEquals(12,a.length());
        assertEquals(24,b.length());
        assertEquals(36,c.length());
    }
    @Test
    public void testindexOf() throws Exception {
        assertEquals(0,a.indexOf("Str"));
        assertEquals(5,a.indexOf("gBu"));
    }


}

三、对MyDoc类进行扩充，让其支持Long类，初步理解设计模式

面向对象三要素是“封装、继承、多态”，任何面向对象编程语言都会在语法上支持这三要素。如何借助抽象思维用好三要素特别是多态还是非常困难的，S.O.L.I.D类设计原则是一个很好的指导：

• SRP(Single Responsibility Principle,单一职责原则)
• OCP(Open-Closed Principle,开放-封闭原则)
• LSP(Liskov Substitusion Principle,Liskov替换原则)
• ISP(Interface Segregation Principle,接口分离原则)
• DIP(Dependency Inversion Principle,依赖倒置原则)

20165335%6=0所以我做的题目是

0： 让系统支持Byte类，并在MyDoc类中添加测试代码表明添加正确，提交测试代码和运行结的截图，加上学号水印

1、代码如下

abstract class Data{
    public abstract void DisplayValue();
}
class Integer extends Data {
    int value;
    Integer(){
        value=100; }
    public void DisplayValue(){
        System.out.println(value);
    }
}
class PaseByte extends Data {
    byte value;
    PaseByte(){
        value=-13;
    }
    public void DisplayValue(){
        System.out.println(value);
    }
}
class Document {
    Data pd;
    Document() {
        pd=new PaseByte() ;
    }
    public void DisplayData(){
        pd.DisplayValue();
    }
}
public class MyDoc {
    static Document d;
    public static void main(String[] args) {
        d = new Document();
        d.DisplayData();
    }
}

四、以TDD的方式开发一个复数类Complex

由于这个程序比较大，所以需要伪代码整理思路

//伪代码如下
（1）属性：复数包含实部和虚部两个部分，
double RealPart;复数的实部
double ImagePart;复数的虚部
getRealPart():返回复数的实部
getImagePart();返回复数的虚部
setRealPart():设置复数的实部
setImagePart();设置复数的虚部
输出形式：a+bi
（2）方法：
①定义构造函数
public Complex()
public Complex(double R,double I)
②定义公有方法:加减乘除
Complex ComplexAdd(Complex a):实现复数加法
Complex ComplexSub(Complex a):实现复数减法
Complex ComplexMulti(Complex a):实现复数乘法
Complex ComplexDiv(Complex a):实现复数除法
③Override Object
public String toString():将计算结果转化为字符串形式并输出

1、产品代码

class Complex {
     private double r;
     private double i;

     public Complex(double r, double i) {
         this.r = r;
         this.i = i;
     }
     public static double getRealPart(double r) {
         return r;
     }
     public static double getImagePart(double i) {
         return i;
     }

     public Complex ComplexAdd(Complex a) {
         return new Complex(r + a.r, i + a.i);
     }

     public Complex ComplexSub(Complex a) {
         return new Complex(r - a.r, i - a.i);
     }
     public Complex ComplexMulti(Complex a) {
         return new Complex(r * a.r - i * a.i , r * a.i + i * a.r);
     }
     public Complex ComplexDiv(Complex a) {
         return new Complex((r * a.i + i * a.r) / (a.i * a.i + a.r * a.r), (i * a.i + r * a.r) / (a.i * a.i + a.r * a.r));
     }
     public String toString() {
         String s =" ";
         if (i > 0)
             s =r +"+"+ i +"i";
         if (i == 0)
             s =r+"";
         if (i < 0)
             s = r +" "+ i+"i";
         return s;
     }
 }

2、测试代码

import junit.framework.TestCase;
import org.junit.Test;
public class ComplexTest extends TestCase {
   Complex a=new Complex(1,2);
   Complex b=new Complex(1,-4);
   Complex c=new Complex(0,0);
   Complex d=new Complex(5,0);
   Complex e=new Complex(0,8);
   @Test
   public void testgetRealPart() throws Exception{
       assertEquals(1.0,Complex.getRealPart(1.0));
       assertEquals(-1.0,Complex.getRealPart(-1.0));
       assertEquals(55.0,Complex.getRealPart(55.0));
       assertEquals(0.0,Complex.getRealPart(0.0));
   }
   @Test
   public void testgetImagePart() throws Exception{
       assertEquals(1.0,Complex.getImagePart(1.0));
       assertEquals(-1.0,Complex.getImagePart(-1.0));
       assertEquals(0.0,Complex.getImagePart(0.0));
       assertEquals(65.0,Complex.getImagePart(65.0));
   }
   @Test
   public void testComplexAdd() throws   Exception{
       assertEquals("2.0 -2.0i",a.ComplexAdd(b).toString());
       assertEquals("1.0 -4.0i",b.ComplexAdd(c).toString());
      assertEquals("5.0",c.ComplexAdd(d).toString());
       assertEquals("5.0+8.0i",d.ComplexAdd(e).toString());
   }
   @Test
   public void testComplexSub() throws   Exception{
       assertEquals("0.0+6.0i",a.ComplexSub(b).toString());
       assertEquals("0.0 -8.0i",c.ComplexSub(e).toString());
   }
   @Test
   public void testComplexMulti() throws   Exception{
       assertEquals("9.0 -2.0i",a.ComplexMulti(b).toString());
       assertEquals("0.0",c.ComplexMulti(d).toString());
   }
   @Test
   public void testComplexDiv() throws   Exception{
       assertEquals("-0.4 -1.4i",b.ComplexDiv(a).toString());
   }

}

实验截图

实验1截图

实验2截图

实验3截图

实验4截图

实验中遇到的问题

• 问题1：在配置好Junit后@Test任然是是红色
• 解决办法：点解@Test旁的灯泡修正后即可。
• 问题2：在做第4个小实验时遇到如图问题

解决办法：根据错误提示已经修改，但想让它能兼容多空格或少空格，不知道如何修改

实验总结

本次实验最大的收获是体会到用junit测试代码的灵活性，以及在实验MyDoc类扩展中体会到抽象编程、抽象和继承、面向接口编程的理解。

步骤	耗时	百分比
需求分析	15min	20%
设计	32min	32%
代码实现	20min	25%
测试	15min	19%
分析总结	10min	4%