Java Basic Learning--object container

Use Java to implement Notepad functionality. Start by listing the features that Notepad requires:

1. You can add records (strings);
2. The number of record bars can be obtained;
3. One of the records can be deleted;
4. A record of the specified section may be obtained;
5. You can list all the records.

If this notepad is part of a large program, that is, a top-level program, then the upper-level program may invoke one of the data listed above in this Notepad.

So we call these multi-column functions as the interface for this notepad.

Then calling these interfaces is the public function (method) of this class through Notepad.

But how do you make a record? It is clear that the recorded string cannot be recorded in an array because the length of the array is pre-set. This is a generic class container arraylist<> , this Arraylist is also a class of the system, so when using it to define a new object to come out: private arraylist<string>  Notes = new arraylist<string> (); also declare import java.util.ArrayList;

ArrayList can be arbitrarily stored in the data, unlimited number, which realizes the requirements of Notepad.

Basic operations for Arraylist: arraylist<string> notes

• Notes.add ()
• Notes.size ()
• Notes.remove (Index)
• Notes.get (Index)
• Notes.toarray (string[] a=new string[notes.size ()])

The interface function of Notepad is implemented by the above operation.

1  Packagenotebook;2 3 Importjava.util.ArrayList;4 5  Public classNotebook {6     7     PrivateArraylist<string> notes =NewArraylist<string>();8     9      Public voidAdd (String s) {Ten Notes.add (s); One     } A      -      Public intGetSize () { -         returnnotes.size (); the     } -      -      Public voidRemovenote (intindex) { - Notes.remove (index); +     } -      +      PublicString Getnote (intindex) { A         returnNotes.get (index); at     } -      -      Publicstring[] List () { -String[] A =Newstring[notes.size ()]; - Notes.toarray (a); -         returnA; in     } -      to      Public Static voidMain (string[] args) {//Test +Notebook NB =NewNotebook (); -Nb.add ("Frist"); theNb.add ("Second"); * System.out.println (Nb.getsize ()); $String[] A =nb.list ();Panax Notoginseng          for(String s:a) { - System.out.println (s); the         } +     } A  the}

Notebook.java

Run:

Java Basic Learning--object container