J2SE5.0 norm programming

J2SE5.0 norm programming

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This chapter is mainly referred to the Sun company documentation.

C programmers are definitely unfamiliar with the model, especially when STL is very difficult, C # 2.0 will also achieve the function of the model programming. Java also does not have to show weakness, and also introduces the new language characteristics of the model programming.

1. A simple model example

Before, you may have encountered this code:

List list = new linkedList (); list.add ("MAS)); List.add (" Princeton "); List.Add (" Berkeley); string name = (String) list.iterator.next () ;

Note that the third line needs to force conversion. Use the model:

List list = new linkedList (); list.add ("MAS)); List.Add (" Princeton); List.Add ("Berkeley); string name = list.iterator. NEXT ();

Here, List is declared into a String type list. List is a model interface with a type of parameters. The type parameters in this example are string.

2. Define simple model

See the implementation of List and Iterator interfaces in J2SE5.0:

Public interface list {void add (e x); item item ();} public interface iterator {e next (); boolean hasnext ();}

We are more familiar with the code, but increasing angle brackets. The contents of the spare brackets define the form of the interface List and Iterator. Type parameters can be used in a model declaration, such as classes, and interface statements.

Once the model is declared, you can use it. List is used in the example above. Here is the use of string is the argument, instead of the meticulum E. If List is used, use the argument with the argument EGER.

Regardless of List or list , their classes have only one. Consider the following code:

List list1 = new limitedList (); list list2 = new linkedList (); system.out.println (list1.getclass () == List2.getClass ());

The output is TRUE.

In general, the form type parameters are uppercase, try to use a single letter, and many container classes use E as parameters.

3. Fan and inheritance

Consider the following code, do you think it will be wrong?

String s = "smallnest@163.com"; Object O = S:

Of course, the String class inherits the Object class, which will not be wrong. But what about the following code?

List s = new linkedlist (); list