Scala - 1. Setup

Need:
1. JDK 1.8
2. Scala Build Tool (sbt), version 0.13x
3. IDE. Scala IDE for Eclipse or Intellij IDEA


1. JDK 1.8
Install JDK and set PATH of the bin direcotry

Check version: java -version

2. sbt
Install sbt.
Check version: sbt about
Compile and run: sbt
then run

3. Intellij IDEA
Install community edition.
Install Scala plugin.
go to Configure → Project defaults → Project structure and add the JDK
To use it, click Create New Project on the Welcome Screen, then select Scala, and finally SBT Project.

Sorting

Insertion Sort

Selection Sort

Merge Sort

Quick Sort

Bubble Sort

Selenium Learning Notes

Selenium IDE

Working and Handling multiple windows
storeTitle i
openWindow
selectWindow
selectWindow ${i}
close i
close

Selenium Webdriver

java learning part2

input and output

文本界面的输入输出
1. 使用Scanner类
java.util.Scanner
nextInt();
nextDouble();
next();
Scanner scanner = new Scanner(System.in);
int a = scanner.nextInt();
System.out.printf("%d\n", a);

2. use java.io
System.in.read()
System.out.print()

输入一行
BufferedReader in = new BufferedReader(new InputStreamReader( System.in ));
s = in.readLine();
ss = in.readLine();
n = Integer.parseInt( ss );
d = Double.parseDouble( ss );

图形界面的输入输出
文本框 TextField 输入
标签 Label 输出
按钮Button 执行命令
首先需要创建一个Frame

java learning part1

path: 命令所在路径 (javac, java etc.)
classpath: 所要引用的类所在的路径

set path=.;c:\jdk\bin...
set path: 查看当前path

javac -cp libxx.jar xxx.java
java -cp libxx.jar xxx
//临时设一下classpath, 用-cp

使用package时的编译
文件和路径一致
程序中使用package语句
使用import语句
javac -d classes src\edu\uiuc\tds\ui\*.java src\edu\uiuc\tds\util\*.java src\edu\uiuc\tds\*.java
java -cp classes edu.uiuc.tds.PackageTest

运行applet
javac xxx.java
appletViewer xxx.html
applet替代物: Flash, SilverLight, javascript, HTML5

javac 编译
java 运行
javaw 运行图形界面
appletViewer 运行applet程序
jar 打包工具
javadoc 生成文档
javap 查看类信息及反汇编

jar打包
javac A.java
jar cvfm A.jar A.man A.class (c create, v显示详情verbose, m表示生成清单文件, f表示指定文件名
java A.jar
A.man一般命名为MANIFEST.MF

javadoc -d 目录名 xxx.java
/** */

Iterator

Iterator, an interface in java.util for iterating sequence of objects.

public interface Iterator {
    boolean hasNext();
    Object next();
    void remove();                          // The remove() method is optional.
  }

An Iterator is like a bookmark.
 Just as you can have many bookmarks in a book, you can have many Iterators iterating over the same data structure, each one independent of the others.

One Iterator can advance without disturbing other Iterators that are iterating over the same data structure.
The first time next() is called on a newly constructed Iterator, it returns the first item in the sequence. Each subsequent time next() is called, it returns the next item in the sequence.
 After the Iterator has returned every item in the sequence, every subsequent call to next() throws an exception and halts with an error message. (I find this annoying; I would prefer an interface in which next() returns null. The Java library designers disagree.)

To help you avoid triggering an exception, hasNext() returns true if the Iterator has more items to return, or false if it has already returned every item in the sequence. It is usually considered good practice to check hasNext() before calling next(). (In the next lecture we'll learn how to catch exceptions; that will give us an alternative way to prevent our program from crashing when next() throws an exception.)

 There is usually no way to reset an Iterator back to the beginning of the sequence. Instead, you construct a new Iterator.

Most data structures that support Iterators "implement" another interface in
java.util called "Iterable".

public interface Iterable {
    Iterator iterator();
  }

怎么用，一般来说，如果想遍历一个数据结构DS，就call DS.iteratre(); 这个method会constructs and returns DSIterator whose fields are initialized so it is ready to return the first item in DS.

例子:

/* list/SListIterator.java */

package list;
import java.util.*;

public class SListIterator implements Iterator {
  SListNode n;

  public SListIterator(SList l) {
    n = l.head;
  }

  public boolean hasNext() {
    return n != null;
  }

  public Object next() {
    if (n == null) {
      /* We'll learn about throwing exceptions in the next lecture. */
      throw new NoSuchElementException();                       // In java.util
    }
    Object i = n.item;
    n = n.next;
    return i;
  }

  public void remove() {
    /* Doing it the lazy way.  Remove this, motherf! */
    throw new UnsupportedOperationException("Nice try, bozo."); // In java.lang
  }
}

/* list/SList.java */

package list;
import java.util.*;

public class SList implements Iterable {
  SListNode head;
  int size;

  public Iterator iterator() {
    return new SListIterator(this);
  }

  [other methods here]
}

Ruby on Rails

Tools:
 Rake - Create/migrate database, clear web session data.
 WEBrick - Web server for hosting Rails web applications.
 SQLite - A simple database system.
 Rack Middleware - Standardized interface for interaction between web server and web application.

rails new hello_www
cd hello_www
rails server (start a web server)

Under hello_www (Rails root):
app: models, views, and controllers code
bin: helper scripts (bundle, rails, rake)
config: App, database and route configuration
db: database schema and migrations
Gemfile: specify the required gems
lib:
log: application logging directory
pulic: webroot of the application
test: Tests - Agile development