Programmer Group

Java programming foundation penultimate article, thank you for not giving up yourself. This column is temporarily over, and the next step is to fix the algorithm. Zhang Huansheng, editor in chief of the reference book "Fundamentals of Java programming". The content of this book is more suitable for beginners without any foundation. Th ...

catalogue preface 1, Collection collection 1. Collection characteristics and architecture 2.Collection collection overview and basic usage 3. Common methods and traversal of collection 4. Collection case - the collection stores student objects and traverses them 2, List collection 1.List set overview, features and unique methods 2. Con ...

4 thread safety of collections 4.1 set operation Demo (demonstration) NotSafeDemo: import java.util.ArrayList; import java.util.List; import java.util.UUID; /*** Collection thread safety case */ public class NotSafeDemo { /** * Multiple threads modify the collection at the same time */ public static void main(String[] args) { L ...

preface In the last issue, we talked about the Collection Set. It is a single column Set, which is divided into List Set and Set set Set. Today, I will continue to analyze a double column Set, that is, Map. Why is it called a double column Set? Look down and you'll see.   catalogue 1, Map 2, Basic concepts of HashMap   3, Ba ...

Java -- collection, IO stream 1. Set (java.util. *) (1) 1. Overview I. a set is actually a container (carrier) that can store multiple objects; (array is the simplest set); II. The basic data type and java object cannot be stored in the collection, but the memory address of the java object is stored; III. the bottom layer of each diff ...

1. General ArrayList implements the List interface and is a sequential container, that is, the data stored in the elements is in the same order as that put in. null elements are allowed to be put in, and the bottom layer is realized through array. Except that this class does not realize synchronization, the rest are roughly the same as Vec ...

2, Collection class unsafe 2.1ArrayList thread is unsafe 2.1.1 example Single thread public class NotSafeDemo { //Single thread is safe public static void main(String[] args) { List<String> list = Arrays.asList("a", "b", "c"); list.forEach(System.out::println); } } a b c Multithreading public class NotS ...

Double column set: key: value public class MapDDDDemo { public static void main(String[] args) { Map map = new HashMap<Integer,String>(); map.put(1,"Hello"); map.put(2,"world"); map.put(3,"hello"); System.out.println("map Length:"+map.size()); System.out.println("map Include key ...

edition JDK8(JDK1.8) Collection interface source code focus 1. The root interface in the set hierarchy. A set represents a group of objects called its elements. Some sets allow repeated elements, while others do not. Some are ordered and some are disordered. 2. The interface class defines various specifications, including method specification ...

Characteristics of Map interface implementation class Map and Collection exist side by side. Used to save data with mapping relationship: key valueThe key and value in the Map can be data of any reference type and will be encapsulated in the HashMap$Node objectDuplicate key s in Map are not allowed. The reason is the same as HashSet. The sourc ...