Java Collections Tool Class

1.reverse Inversion
2.shuffle Random Sorting
3.sort Natural Sort
4.sort specifying the Comparer sort
5.swap swap the elements of the subscript position for X and Y
6.max Maximum Value
7.min Minimum value
8.frequency number of calculated elements
9.copy Copy List
10.replaceAll Replace all elements

ImportJava.util.*;/*** Created by Meicai on 2017/11/6.*/ Public classtestcollections { Public Static  voidMain (string[] args) {test10 (); }    /*Reverse Reverse 123*/    Private Static voidtest1 () {List<Integer> numlist= arrays.aslist (123,22,85,44);        Collections.reverse (numlist);    Numlist.foreach (System.out::p rintln); }    /*** Shuffle random sort *22-123*/    Private Static voidtest2 () {List<Integer> numlist= arrays.aslist (123,22,85,44);        Collections.shuffle (numlist);    Numlist.foreach (System.out::p rintln); }    /**3.sort Natural Sort * 123*/    Private Static voidtest3 () {List<Integer> numlist= arrays.aslist (123,22,85,44);        Collections.sort (numlist);    Numlist.foreach (System.out::p rintln); }    /*** Sort Specifies the comparator sort, using anonymous inner class * 123*/    Private Static voidTest4_1 () {List<Integer> numlist= arrays.aslist (123,22,85,44); Collections.sort (Numlist,NewComparator<integer>() {@Override Public intCompare (integer O1, integer o2) {return-O1.compareto (O2);                }                }                );    Numlist.foreach (System.out::p rintln); }    /*** Sort Specifies the comparator sort, using the java8 lambda expression * 123*/    Private Static voidTest4_2 () {List<Integer> numlist= arrays.aslist (123,22,85,44); Collections.sort (Numlist, (T1,T2)->{return-T1.compareto (t2);});    Numlist.foreach (System.out::p rintln); }    /*** Swap swaps the elements with the subscript position x and Y * 123*/    Private Static voidTest5 () {List<Integer> numlist= arrays.aslist (123,22,85,44); Collections.swap (Numlist,1,3);    Numlist.foreach (System.out::p rintln); }    /*** Max * max:123*/    Private Static voidTest6 () {List<Integer> numlist= arrays.aslist (123,22,85,44); Integer Max=Collections.max (numlist); System.out.println ("Max:" +max); }    /*** Frequency Returns the number of each element in the collection *count:2*/    Private Static voidtest7 () {List<Integer> numlist= arrays.aslist (123,22,85,44,22); intCount= Collections.frequency (numlist,22); System.out.println ("Count:" +count); }    /*** Copy exception, error usage *exception in thread ' main ' Java.lang.IndexOutOfBoundsException:Source does not fit in dest */    Private Static voidTest8 () {List<Integer> numlist= arrays.aslist (123,22,85,44,22); List<Integer> numlistcopy=NewArraylist<>();        Collections.copy (numlistcopy,numlist);    Numlistcopy.foreach (System.out::p rintln); }    /**copy Correct use method * 123*/    Private Static voidTest9 () {List<Integer> numlist= arrays.aslist (123,22,85,44,22); List<Integer> Numlistcopy=arrays.aslist (Newinteger[numlist.size ()]);        Collections.copy (numlistcopy,numlist);    Numlistcopy.foreach (System.out::p rintln); }    /*** ReplaceAll Replace all elements * 123 222 222*/    Private Static voidtest10 () {List<Integer> numlist= arrays.aslist (123,22,85,44,22); Collections.replaceall (Numlist,22,222);    Numlist.foreach (System.out::p rintln); }}

Basic Way to use demo

11. Switch from a thread-unsafe list to a thread-safe list

Private Static void test11 () {        List<Integer> numlist= arrays.aslist (123,22,85,44);        List<Integer> synchronizedlist= collections.synchronizedlist (numlist);        Synchronizedlist.foreach (System.out::p rintln);    }

from a thread-unsafe list to a thread-safe list

Use of 12.Enumeration

  /**      * Enumeration Use     * A1     A2     A3     */    privatestatic void test12 () {        enumeration e=new stringtokenizer ("A1-a2-a3", "-");          while (E.hasmoreelements ()) {            System.out.println (e.nextelement ());        }    }

use of enumeration

Java Collections Tool Class