Java Basic Knowledge Hardening Collection Framework note 27:arraylist collection exercises to remove duplicate string elements from the ArrayList collection

1. Remove duplicate string elements from the ArrayList collection (same string content)

Analysis:

(1) Creating a Collection Object

(2) Adding multiple string elements (containing duplicates)

(3) Create a new collection

(4) Iterate through the old collection to get each element

(5) Take an element to the new set and look for it.

Have: ignore it

No: Add to new collection

(6) Traversing a new collection

2. Case code:

1  Packagecn.itcast_04;2 3 Importjava.util.ArrayList;4 ImportJava.util.Iterator;5 6 /*7 * ArrayList removes duplicate values of strings in the collection (the contents of the string are the same)8  * 9 * Analysis:Ten * A: Create A Collection Object One * B: Add multiple string elements (containing the same content) A * C: Create a new collection - * D: Traverse old collection, get each element - * E: Take this element to the new collection to find out, see if there is the * have: ignore it - * No: Add to new collection - * F: Traverse new Collection -  */ +  Public classArraylistdemo { -      Public Static voidMain (string[] args) { +         //To create a collection object AArrayList array =NewArrayList (); at  -         //add multiple string elements (containing the same content) -Array.add ("Hello"); -Array.add ("World"); -Array.add ("Java"); -Array.add ("World"); inArray.add ("Java"); -Array.add ("World"); toArray.add ("World"); +Array.add ("World"); -Array.add ("World"); theArray.add ("Java"); *Array.add ("World"); $ Panax Notoginseng         //Create a new collection -ArrayList NewArray =NewArrayList (); the  +         //iterate through the old collection, get each element AIterator it =array.iterator (); the          while(It.hasnext ()) { +String s =(String) It.next (); -  $             //take this element to the new collection and look for it. $             if(!Newarray.contains (s)) { - Newarray.add (s); -             } the         } - Wuyi         //Traverse a new collection the          for(intx = 0; x < Newarray.size (); X + +) { -String s =(String) newarray.get (x); Wu System.out.println (s); -         } About     } $}

The results are as follows:

Java Basic Knowledge Hardening Collection Framework note 27:arraylist collection exercises to remove duplicate string elements from the ArrayList collection