Key points: Java20java. util. Collections

Java. util. collections collection help class example Program (JUnit demo) sorting @ TestpublicvoidtestSort () {ListIntegerdemoListnewArrayListInteger (Arrays. asList (3, 2, 1); assertEquals (3, demoList. get (0 ). intValue (); publicstaticTextendsComparable

Java. util. collections collection help class example Program (JUnit demo) sorting @ Test public void testSort () {ListInteger demoList = new ArrayListInteger (Arrays. asList (3, 2, 1); assertEquals (3, demoList. get (0 ). intValue (); // public static T extends Comparable

Java. util. Collections collection help class example Program (JUnit demo) sorting

@ Test public void testSort () {List
  
   
DemoList = new ArrayList
   
    
(Arrays. asList (3, 2, 1); assertEquals (3, demoList. get (0). intValue (); // public static
    
     
> Void sort (List
     
      
List) Collections. sort (demoList); assertEquals (1, demoList. get (0). intValue (); // public static void shuffle (List
      List) // random sorting // public static void reverse (List
      List) // Reverse Order}
     
    
   
  

Search

@ Test public void testBinarySearch () {List
   
    
DemoList = new ArrayList
    
     
(Arrays. asList (3, 2, 1); // you must first sort Collections. sort (demoList); assertEquals (1, demoList. get (0 ). intValue (); // Binary Search location // public static
     
      
Int binarySearch (List
      > List, T key) assertEquals (0, Collections. binarySearch (demoList, 1); // public static int indexOfSubList (List
      Source, List
      Target) // public static int lastIndexOfSubList (List
      Source, List
      Target )}
     
    
   

Replacement

@ Test public void testSwap () {List
    
     
DemoList = new ArrayList
     
      
(Arrays. asList (3, 2, 1); // public static void swap (List
      List, int I, int j) Collections. swap (demoList, 0, 2); assertEquals (1, demoList. get (0 ). intValue (); // public static void rotate (List
      List, int distance) // specify the distance rotation // public static
      
       
Boolean replaceAll (List
       
        
List, T oldVal, T newVal) // specifies the replacement}
       
      
     
    

Copy

@ Test public void testCopy () {List
     
      
DemoList = new ArrayList
      
       
(Arrays. asList (3, 2, 1); // public static
       
        
Void copy (List
        Dest, List
        Src) // note that the size of the destination List must be equal to the size List of src at least.
        
         
CopyList = new ArrayList
         
           (Arrays. asList (1, 2, 3); Collections. copy (copyList, demoList); assertEquals (3, copyList. size (); assertEquals (3, copyList. get (0 ). intValue (); copyList. add (4); assertEquals (3, demoList. size ());}
         
        
       
      
     

Comparison

    @Test    public void testCompary() {        List
      
        demoList = new ArrayList
       
        (Arrays.asList(3, 2, 1));        assertEquals(1, Collections.min(demoList).intValue());        assertEquals(3, Collections.max(demoList).intValue());        List
        
          compareList = new ArrayList
         
          (Arrays.asList(5, 6, 7));        //Returns true if the two specified collections have no elements in common        assertTrue(Collections.disjoint(demoList, compareList));    }
         
        
       
      

Create different sets

@ SuppressWarnings ("unused") @ Test public void testCreate () {List
       
        
DemoList = new ArrayList
        
         
(Arrays. asList (3, 2, 1); // empty object size = 0 No add method List
         
          
EmptyList = Collections. emptyList (); // returns an unchangeable list containing only the specified object. List
          
           
SingletonList = Collections. singletonList (1); // return a dynamic security view of the specified list. List
           
             CheckedList = Collections. checkedList (demoList, Integer. class); // return the unchangeable view of the specified list. List
            
              UnmodifiableList = Collections. unmodifiableList (demoList); // return the synchronization (thread-safe) List supported by the specified list. List
             
               SynchronizedList = Collections. synchronizedList (demoList); synchronized (synchronizedList) {Iterator
              
                I = synchronizedList. iterator (); // Must be in synchronized block while (I. hasNext () I. next ();} // map set sortedMap sortedSet}
              
             
            
           
          
         
        
       

Environment jdk1.6 window7 junit4