cs108 java 02

Eclipise

1. import, 所有的homework 是以 eclipse project directories 的形式.

所以要选择 “File –> Import “, Existing project “, 选择 “copy to workspace” option will copy the project directory into Eclipse’s workspace directory.

2. debugging

double click in the editor at the left of a line to set a breakpoint on that line.

Use “Debug” instead of “Run” to run in the debugger.

3. Eclipse 特性

看自己总结的eclipse快捷键更好一点.

Unit test( 单元测试 )

Unit test 的目的, for each piece of "work" code --a class or a method, pair the work code with some "unit test" code ( 每完成一个类或方法就测试一下 )

这种测试不用是 "exhaustive", 非常完整的测试, 功能实现没问题, 基本数据测试就可以了.

Unit tests are a standard, maintained way to keep tests in parallel with the work code

只要测试一些明显的, 基本的数据就可以了.

Right-click on the class to be tested.

Junit 很流行, new-> JUnit Test case, 比如类名为 Binky, 那么测试的类名为 BinkyTest. (自动生成的)

这个生成是在本 project 内完成的.

Junit 依赖一些类, file: junit.jar 添加的办法: -自动添加-, 当你选择new->Junit Test case时, 如果第一次, eclipse会提示你让你安装 Junit.jar, -手动安装-, properities, –> Java Build Path –> Libraries –> Add Jar button .

测试方法的话, 比如方法名叫 Foo, 那么测试的方法名为 testFoo(), 像下边的

@Test

public void testFoo() {}

Example 1

1. CLASS

 import java.util.*;

 /*
  * Emails class -- unit testing example.
  * Encapsulates some text with email address in it.
  * getUsers() returns a list of the usernames from the text.
  */
 public class Emails {

     // Sets up a new Emails obj with the given text

     public Emails(String text) {
         this.text = text;
     }

     // Returns a list of the usernames found in the text.
     // We'll say that a username is one or more letters, digits,
     // or dots to the left of a @.

     public List<String> getUsers() {
         int pos = 0;
         List<String> users = new ArrayList<String>();

         while (true) {
             int at = text.indexOf('@', pos);
             if (at == -1) break;

             // Look backwards from at
             int back = at - 1;
             while (back >=0 &&
                     (Character.isLetterOrDigit(text.charAt(back)) || text.charAt(back) == '.')) {
                 back--;
             }
             // Now back is before start of username
             String user = text.substring(back+1, at);

             if (user.length() > 0) users.add(user);

             // Advance pos for next time
             pos = at + 1;

         }
         return users;
     }

     /* private values */
     private String text;

 }

CLASS

2. TEST CLASS

 import static org.junit.Assert.assertEquals;

 import java.util.Arrays;
 import java.util.Collections;

 import org.junit.Test;

 /**
  * EmailsTest -- unit tests for the Emails class.
  * @author Ronnie
  *
  */
 public class EmailsTest {

     // Basic use
     @Test
     public void testUsersBasic() {
         Emails emails = new Emails("foo bart@cs.edu xyz marge@ms.com baz");
         assertEquals(Arrays.asList("bart", "marge"), emails.getUsers());
         // Note: Array.asList(...) is a handy way to make list literal.
         // Also note that .equals() works for collections, so the above works.
     }

     // Weird chars -- push on what chars are allowed
     @Test
     public void testUsersChars() {
         Emails emails = new Emails("fo f.ast@cs.edu bar&a.2.c@ms.com");
         assertEquals(Arrays.asList("f.ast", "a.2.c"), emails.getUsers());
     }

     // Hard cases -- push on unusual, edge cases
     @Test
     public void testUsersHard() {
         Emails emails = new Emails("x y@cs 3@ @z@");
         assertEquals(Arrays.asList("y", "3", "z"), emails.getUsers());

         // No emails
         emails = new Emails("no emails here!");
         assertEquals(Collections.emptyList(), emails.getUsers());

         // All @, all the time!
         emails = new Emails("@@@");
         assertEquals(Collections.emptyList(), emails.getUsers());

         // Empty string
         emails = new Emails("");
         assertEquals(Collections.emptyList(), emails.getUsers());

     }

 }

TEST CLASS

Example 2

 public class Myunit {
     public String concatenate(String one, String two) {
         return one + two;
     }
 }

 //========================================

 import static org.junit.Assert.*;

 import org.junit.Test;

 public class MyunitTest {

     @Test
     public void testConcatenate() {
         Myunit myUnit = new Myunit();

         String result = myUnit.concatenate("one", "two");
         assertEquals("onetwo", result);
     }

 }

ALL

以上代码中, Unit Test 目的是测试所有的 public 方法, 在上例中, 只有1个public 方法就是 concatenate, 一般来讲, 每个测试方法对应一个方法, 命名方式为 test该方法名, 例如 testConcatenate, 但是也有几个测试方法对应一个方法的情况, 比如要测试的方法很大. assertEquals 很明显是用来比较的, 比较你要的结果是否和程序得出的结果一直. The asserEquals() method is a statically imported method, which normally resides in the org.junit.Assert class.

用来测试的方法上边有个 @Test 用来注释,表示这个方法是一个 unit test.  注意这样有一个好处就是, 这个方法在eclipse中可以运行(没有 main 方法 ), 如果没有这个@Test标志, 那么这个测试方法将无法运行.