Fourth chapter Copyonwritearrayset Source code Analysis

Note: Before looking at this article, if the bottom of the copyonwritearraylist is not clear, it is recommended to first look at Copyonwritearraylist source parsing.

Http://www.cnblogs.com/java-zhao/p/5121944.html

1, for Copyonwritearrayset need to master the following points

• Created: Copyonwritearrayset ()
• add element: That is, the Add (E) method
• Delete object: Remove (E) method
• Traversing all objects: iterator (), which is more commonly used in practice is the enhanced for loop to do traversal

Note:

• Copyonwritearrayset (Cannot add duplicate elements) the underlying is copyonwritearraylist (can add repeating elements).
• The set collection does not get or modify or add or remove methods directly by index (eg.get (int index), add (int index,e e), set (int index,e e), remove (int index))

2. Create

Public Copyonwritearrayset ()

How to use:

New Copyonwritearrayset<string> ();

Source:

    Private Final Copyonwritearraylist<e> al; // underlying data structure     Public Copyonwritearrayset () {        new copyonwritearraylist<e>();    }

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Note the point:

• The bottom of Copyonwritearrayset is a copyonwritearraylist.

3. Adding elements

Public boolean Add (E E)

How to use:

Strset.add ("Hello")

Source:

    /**      * Loop through the old array, if there is the same value as E, return false     * If not, to the     last interpolation */ public     Boolean  Add (e e) {        return  al.addifabsent (e);    }

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Copyonwritearraylist's Addifabsent (e e)

     Public Booleanaddifabsent (e e) {FinalReentrantlock lock = This. Lock;        Lock.lock (); Try{object[] elements=GetArray (); intLen =elements.length; Object[] Newelements=NewObject[len + 1];  for(inti = 0; i < Len; ++i) {if(EQ (E, elements[i]))//Loop through it first to see if there's a value that's the same value you want to insert.                    return false;//If there is, return directly                ElseNewelements[i]=Elements[i]; } Newelements[len]= e;//if not, assign a valueSetArray (newelements); return true; } finally{lock.unlock (); }    }

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Note: This together source code is very simple, as long as you read the Copyonwritearraylist source parsing in the Add method can read

Note the point:

• Copyonwritearrayset every time the add has to go through the group, performance is lower than copyonwritearraylist

4. Deleting elements

public boolean remove (Object o)

How to use:

Strset.remove ("Hello")

Source:

    /**      * Call Copyonwritearraylist's remove (Object O) method     */ public     boolean Remove (Object o) {        return  al.remove (o);    }

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5. Traverse all elements

Public iterator<e> Iterator ()

How to use: See the previous chapter "Copyonwritearraylist Source Code Analysis"

Source:

    /**      * Call Copyonwritearraylist's Iterator ()     */public     iterator<e>  Iterator () {        return  al.iterator ();    }

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The remaining source code see the previous chapter "Copyonwritearraylist Source Code Analysis"

Summarize:

• The bottom of Copyonwritearrayset is a copyonwritearraylist.
• Copyonwritearrayset in the add element to iterate through the array, so as not to add duplicate elements of the role, but because to go through the group, the efficiency will be lower than the Copyonwritearraylist add
• The set collection does not get or modify or add or remove methods directly by index (eg.get (int index), add (int index,e e), set (int index,e e), remove (int index))

Fourth chapter Copyonwritearrayset Source code Analysis