The first high-level language that I learned was Java. Of course I shortly found that there was a need to know C# too. So, as I started to learn C# I kept a list of the differences between C# and Java (as can m be seen below).
Class
--------
Java: class GMTTime extends Time implements ICloneable{...}
C#: class GMTTime: Time, ICloneable{...}Constructor
-----------
Java: GMTTime(){
this(System.DateTime.Now);
} C#:GMTTime():this(System.DateTime.Now){...}
GMTTime(long millis): base(millis){...}//if base not specified default constructor
//called
Java = C#
---------------------------
Finalizer = destructors //spedifies code that will execute once an object is no
//longer usable
Package = namespace
import = using
StringBuffer = StringBuilder
indexer: allows a class to be accessed as an array
struct: lightweight class, value type instead of reference type (like class)
Method Inheritance
-------------------
class BaseClass{
//virtual is required to allow this method to be overridden by a sub class
virtual long GetTime(){...}
}
class childClass: BaseClass {
//override allows an object to be a base class (BaseClass) but will still use
//this method
override long GetTime(){...}
}
class childClass2: BaseClass {
//new overwrites the method but uses the method of the class that the calling
//object is.
new long GetTme(){...}
}
Java Final
----------
class = sealed //can not be inherited
method = no virtual
variable = const or readonly
Accessibility
-------------
public = visible to all
protected = only derived classes
private = only withen given class
internal = visible only to project/assembly/jar file
protected internal = visible only to project/assembly/jar file and derived classes
default = private
Getters/Setters
---------------
//new C# way...old way used getter and setter methods
class Circle {
private int radius;
public int Radius {
get {return radius;}
set {radius = value;}
}
public int Area {
get { return 3.14 * radius * radius; }
}
}
class otherClass{
Circle c = new Circle();
c.Radius = 3;//Note: no need to call a setter method.
int area = c.Area;//Note no need to call a getter method
}
synchronous = responds immediately
asynchronous = responds when ready to.
How to do events in C#
-----------------------------
1. Manually Trigger Event
//namespace level, also specifies signature for event/handling methods
public delegate void MyEventHandler();
2. Create an Event (requires a delegate)
public event MyEventHandler TriggerIt;//class level
3. Register the event handlers with the event
obj.TriggerIt += new MyEventHandler(obj.method);
4. Manually Trigger Event
obj.TriggerIt();
// Declare the delegate handler for the event:
public delegate void MyEventHandler();//determines signitures of handling methods.
class TestEvent{
// Declare the event implemented by MyEventHandler.
public event MyEventHandler TriggerIt;
public void MyMethod1(){
System.Console.WriteLine("Hello!");
}
public void MyMethod2(){
System.Console.WriteLine("Hello again!");
}
public void MyMethod3(){
System.Console.WriteLine("Good-bye!");
}
static void Main(){
TestEvent myEvent = new TestEvent();
// Subscribe to the event by associating the handlers with the events:
myEvent.TriggerIt += new MyEventHandler(myEvent.MyMethod1);
myEvent.TriggerIt += new MyEventHandler(myEvent.MyMethod2);
myEvent.TriggerIt += new MyEventHandler(myEvent.MyMethod3);
// Trigger the event:
myEvent.TriggerIt();
// Unsuscribe from the the event by removing the handler from the event:
myEvent.TriggerIt -= new MyEventHandler(myEvent.MyMethod2);
System.Console.WriteLine("\"Hello again!\" unsubscribed from the event.");
// Trigger the new event:
myEvent.TriggerIt();
}
}
typeof, GetType, is
----------------------
Type s = typeof(String);
Type s = "my String".GetType();
"my string" is String //returns true
Array
-----
MyArray[column,row]
int[] arr = new int[]{1,2,3);
int[] arr = {1,2,3};
foreach(int i in arr){
Console.WriteLine("Value is {0}",i);
}
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