Collection Framework Tool Class collections

* Collections Demo.

* 1, the tool class for manipulating the collection.

* 2, provides a lot of static methods.

 *

* For example , sort the list set, binary search, position substitution.

* Reverse the order of the ordered elements. Reverseorder

* You can also get the maximum and minimum values for the collection.

* The most bull is to turn the Unsynchronized collection into a synchronized set synchronizedxxx

package cn.itcast.p4.collections; import java.util.arraylist;import java.util.collection; import java.util.collections;import java.util.comparator;import java.util.iterator;import  java.util.list; import cn.itcast.p2.comparator.comparatorbylength;      Public class collectionsdemo {    public static void main ( String[] args)  {        sortdemo ();     } &NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;//1, demonstrates sorting in collections, sorting elements in a repeating set, Is the method for list.     public static void sortdemo () {         List<String> list = new ArrayList<String> ();         list.add ("abc");         list.add (" Aaaaaaa ");          list.add ("Hahah");         list.add ("CBA &NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;SYSTEM.OUT.PRINTLN (list);//list set itself ordered, not sorted          //sorting method.         //collections.sort (list);//sorted by dictionary order                   //collections.sort (list,new  comparatorbylength ());//Comparator sort, sort by string length                   //collections.sort (List,collections.reverseorder ());//Sort reversal by dictionary                   //collections.sort ( List,collections.reverseorder (New comparatorbylength ()));//Reverse the sequencing of existing comparators                   //String max = collections.max (list);//Get the final value under the natural sort                   //string max = collections.max (list,new  Comparatorbylength ());//Get the bottom row of the comparator in the last value                   string max = mymax (list);//custom Gets the maximum value in dictionary order,                  //String max =  Mymax (List,new comparatorbylength ());//maximum value obtained by the order of comparators                   system.out.println ("max=" +max);     &NBSP;&NBSP;&NBSP;&NBSP;SYSTEM.OUT.PRINTLN (list);    }         //simulates a Max method. Gets the maximum value in the collection.     public static <T extends Object & Comparable<?  super t>> t mymax (Collection<? extends t> coll) {         iterator<? extends t> it = coll.iterator ();         //defines a variable that records a larger value.         t max = it.next ();         while (It.hasnext ()) {             t temp = it.next ();             if (Temp.compareto (max) >0) {                 max  = temp;             }        }         return max;    }                   public static  String mymax (Collection<string> coll, comparator<string> comp) {     iterator<string> it = coll.iterator ();         //defines a variable that records a larger value.         string max = it.next ();         while (It.hasnext ()) {             string temp = it.next ();             if (Comp.compare (Temp, max) >0) {                 max  = temp;             }        }         return max;    }     } 

Collection Framework Tool Class collections