Collections Collection Class Usage methods

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package com.fish.util;import java.util.arraylist;import java.util.collections;/*  Collection of tool classes (collections)   Tell the difference between collection and collections?  1,  collection is the root interface of a singleton collection, and collections is a tool class for manipulating objects.   collections: Common method:   1, a binary search for list: If the set must be ordered.  int binarysearch (List,key);  //must sort the list by the natural order of the Elements  int binarysearch (List,key, Comparator);  //requires that the elements in the list  collection are subclasses of comparable . &NBSP;&NBSP;2, sorts the list collection.  sort (list);  //sorts the list, actually uses the CompareTo method of the object in the list container  sort (list,comaprator);  //sort by the specified comparer   3, the maximum or minimum value for the collection.  max (Collection)  max (collection,comparator)  min (Collection)  min (collection,comparator)   4, reverses the list collection.  reverse (list);   5, you can change the Unsynchronized collection to a synchronized collection.  set synchronizedset (set<t> s)  map synchronizedmap (Map<K,V> m)   List synchronizedlist (list<t> list)  */  public class demo1&nbsP {    public static void main (String[] args)  {         ArrayList<Integer> list = new ArrayList<Integer> ();         list.add (1);         list.add (        list.add) (2);         list.add (;             )    //  sort         collections.sort (list);  &NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;SYSTEM.OUT.PRINTLN ("The index value at which the element is located is:"  + collections.binarysearch (list, 12)); &NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;SYSTEM.OUT.PRINTLN ("Maximum Value:"  + collections.max (list)); &NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;SYSTEM.OUT.PRINTLN ("Minimum Value:"  + collections.min (list));  &Nbsp;      collections.reverse (list);  //Flip no need to sort                  system.out.println ("Elements of the collection:"  +  list);                 List= (arraylist<integer>)  collections.synchronizedlist (list);//Convert list to Thread-safe method      }}

package com.fish.util;import java.util.arraylist;import java.util.collections;import  Java.util.comparator;class person{    string name;    int  age;        public person (String name, int  Age)  {        this.name = name;         this.age = age;    }          @Override     public string tostring ()  {         return  "{name:" +this.name+ "  Age:" +this.age+ "}";     }}class  AgeComparator implements Comparator<Person>{     @Override      public int compare (PERSON&NBSP;O1,&NBSP;PERSON&NBSP;O2)  {        &nbSp;return o1.age-o2.age;    }}    public class demo2  {        public static void main (String[]  args)  {            ArrayList<Person>  list = new ArrayList<Person> ();             list.add (New person ("Dog Doll");             list.add (New person ("Zhang San"));             list.add (New person ("John Doe", 2));                          Collections.sort (List,new agecomparator ());                   &NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;SYSTEM.OUT.PRINTLN ("The index value where the element is located is:" +collections.binarysearch (list, new  person ("Zhang San", (),  new agecomparator ()));                         system.out.println (" Maximum value: "+collections.max (List,new agecomparator ()));             system.out.println ("min:" +collections.min (List,new agecomparator ()));                          collections.reverse (list);  //flipping does not need to be sorted, so incoming comparators are not required              system.out.println ("Elements of the collection:" +list);         }}

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Collections Collection Class Usage methods