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[Reprint] Detailed explanation of the relationship between ArrayList, List, LinkedList, and Collection in java
Reprint link: http://www.cnblogs.com/liqiu/p/3302607.html Detailed explanation of the relationship between ArrayList, List, LinkedList, and Collection in java 1. Basic introduction (Set, List, Map) Set (set): The elements in the set are not ordered in a particular way, and there are no duplicate objects. Some of its implementation classes can sort objects in a collection in a specific way. List (list): The elements in the collection are sorted by index position. There can be duplicate objects, allowing objects to be retrieved according to their index position in the collection. Map (mapping): Each element in the collection contains a pair of key objects and value objects. There are no duplicate key objects in the collection, and the value objects can be repeated. Some of its implementation classes can sort key objects in a collection. 2. Basic interfaces and types 1. Iterator interface This interface allows traversing all elements in the collection. There are three methods: public boolean hasNext(): Determine whether there is a next element. public Object next(): Get the next element. Note that the return value is Object and may require type conversion. If there are no more elements available, a NoSuchElementException is thrown. Before using this method, you must first use…
[Reprint] Detailed explanation of the relationship between ArrayList, List, LinkedList, and Collection in java
Reprint link: http://www.cnblogs.com/liqiu/p/3302607.html Detailed explanation of the relationship between ArrayList, List, LinkedList, and Collection in java 1. Basic introduction (Set, List, Map) Set (set): The elements in the set are not ordered in a particular way, and there are no duplicate objects. Some of its implementation classes can sort objects in a collection in a specific way. List (list): The elements in the collection are sorted by index position. There can be duplicate objects, allowing objects to be retrieved according to their index position in the collection. Map (mapping): Each element in the collection contains a pair of key objects and value objects. There are no duplicate key objects in the collection, and the value objects can be repeated. Some of its implementation classes can sort key objects in a collection. 2. Basic interfaces and types 1. Iterator interface This interface allows traversing all elements in the collection. There are three methods: public boolean hasNext(): Determine whether there is a next element. public Object next(): Get the next element. Note that the return value is Object and may require type conversion. If there are no more elements available, a NoSuchElementException is thrown. Before using this method, you must first use…
[Reprint] Detailed explanation of the relationship between ArrayList, List, LinkedList, and Collection in java
Reprint link: http://www.cnblogs.com/liqiu/p/3302607.html Detailed explanation of the relationship between ArrayList, List, LinkedList, and Collection in java 1. Basic introduction (Set, List, Map) Set (set): The elements in the set are not ordered in a particular way, and there are no duplicate objects. Some of its implementation classes can sort objects in a collection in a specific way. List (list): The elements in the collection are sorted by index position. There can be duplicate objects, allowing the object to be retrieved according to the index position of the object in the collection. Map: Each element in the collection contains a pair of key objects and value objects. There are no duplicate key objects in the collection, and the value objects can be repeated. Some of its implementation classes can sort key objects in a collection. 2. Basic interfaces and types 1. Iterator interface This interface allows traversing all elements in the collection. There are three methods: public boolean hasNext(): Determine whether there is a next element. public Object next(): Get the next element. Note that the return value is Object and may require type conversion. If there are no more elements available, a NoSuchElementException is thrown. Before using this method, you…
The differences between basic Java collection classes such as ArrayList, LinkedList, HashMap, and HashTable
Blog from: http://blog.csdn.net/liuxian13183, please indicate the source when reprinting! All Rights Reserved ! ArrayList is a dynamic array with subscripts LinkedList is a doubly linked list, with one pointer pointing to the next one Same points: they both inherit from Collections class and store dynamic data. Differences: The latter has pointers. To add a piece of data, you only need to disconnect one connection and connect the new data respectively Delete a piece of data. The difference is that if the data is in the middle of the array, the latter only needs to find the data, disconnect a connection, and connect the data on both sides; The former requires shifting all subsequent data Modification, for the latter, means deletion + addition; while the latter requires shifting. Search, the former is convenient to search through subscripts, while the latter requires a pointer to point to the next pointer to find data, which is slower. Vector is implemented using an array. In fact, it is the same as ArrayList. The only difference lies in the implementation of synchronization, that is, different threads can share the same data. But it will not lock traversals such as iterator, only common operations such as…
Java basic collection framework (1)–Collection, List, LinkedList, HashSet
Collection frame diagram: Collection interface: [java] view plaincopy import java.util.*; /* Collection defines the common functions of the collection framework. 1, add add(e); addAll(collection); 2, delete remove(e); removeAll(collection); clear(); 3, judge. contains(e); isEmpty(); 4, get iterator(); size(); 5, get the intersection. retainAll(); 6, collection variable array. toArray(); 1. The parameter type of the add method is Object. to receive any type of object. 2. All objects stored in the collection are references (addresses) What is an iterator? In fact, it is a way to remove elements from a collection. It’s like the clip in the doll game machine. The iterator is a retrieval method and will directly access the elements in the collection. So the iterator is described in the form of an inner class. Obtain the object of the inner class through the iterator() method of the container. */ class CollectionDemo { public static voidComplex elements. */ class HashSetTest { public static void sop(Object obj) { System.out.println(obj); } public static void main(String[] args) { HashSet hs = new HashSet(); hs.add(new Person(“a1” ,11)); hs.add(new Person(“a2”,12)); hs.add(new Person(“a3” ,13)); // hs.add(new Person(“a2”,12)); // hs.add(new Person(“a4”,14)); //sop(“a1:”+hs.contains(new Person(“a2”,12))); // hs.remove(new Person(“a4”,13)); Iterator it = hs.iterator(); while(it.hasNext()) Person p = (Person)it.next(); sop(p.getName()+“::”+p.getAge());…
[Reprint] Detailed explanation of the relationship between ArrayList, List, LinkedList, and Collection in java
Reprint link: http://www.cnblogs.com/liqiu/p/3302607.html Detailed explanation of the relationship between ArrayList, List, LinkedList, and Collection in java 1. Basic introduction (Set, List, Map) Set (set): The elements in the set are not ordered in a particular way, and there are no duplicate objects. Some of its implementation classes can sort objects in a collection in a specific way. List (list): The elements in the collection are sorted by index position. There can be duplicate objects, allowing the object to be retrieved according to the index position of the object in the collection. Map: Each element in the collection contains a pair of key objects and value objects. There are no duplicate key objects in the collection, and the value objects can be repeated. Some of its implementation classes can sort key objects in a collection. 2. Basic interfaces and types 1. Iterator interface This interface allows traversing all elements in the collection. There are three methods: public boolean hasNext(): Determine whether there is a next element. public Object next(): Get the next element. Note that the return value is Object and may require type conversion. If there are no more elements available, a NoSuchElementException is thrown. Before using this method, you…
Comparison and summary of ArrayList, Vector, LinkedList, HashMap, HashTable, and HashSet in Java
1. The parent class of all collections is the Collection interface 2.Set List Map difference A In the Set, the order of elements cannot be added, so the elements in the Set cannot be repeated B In the List, there is an index Number，is similar to an array，the elements in it can be repeated，the order of addition can be remembered C In Map：each item has a key value Pair composition (key, value) 3.iteratorInterface(Iterator,Traverser): This interface is also Java Members of the collection framework，This interface is mainly used for traversal(iterative access)CollectionElements MainlyUse three methods: A boolean hasNext()：Returns true if the iterated collection elements have not been traversed yet， B Object next()：returns the next element in the collection element,Cursor. The element returned by the next method. 4. Differences in the use of Vector and ArrayList – All in the Vector class The methods are all thread synchronized – it will be safe for multiple…
Detailed explanation of javaArrayList, LinkedList, HashSet, HashMap, Hashtable, Collection, and Collections
1.ArrayList ArrayList is the implementation class of the List interface – a variable-sized array – the capacity will automatically expand as the number of elements increases – ;The default initial capacity value is 10，You can also specify the initial capacity yourself The data structure used：array（Linear table：array, linked list, Queue, stackNonlinear table：Binary tree, heap, graph, etc.） Advantages of ArrayList：Fast query speedDisadvantages of ArrayList ： Adding and deleting elements is slow The reason for fast query speed： The bottom layer of ArrayList is implemented by array ，Query based on subscript& #xff0c; No need to compare. The query method is “first address” Number of bytes ，So very fast； The reason for slow addition and deletion： Addition and deletion will bring about the movement of elements，Increasing data will Moving backward ，Deleting data will move forward，So it affects efficiency Applicable scenarios： If the application has more random access to data, use ArrayList Better 2. LinkedList LinkedList is also an implementation class of the List interface. It has similar functions to ArrayList, but LinkedList has several new functions, such as addFirst() , addLast(), getFirst(), getLast(), etc. Data structure ： Two-way linked list Linked storage ， is not stored continuously in memory& #xff0c; Each element storage includes…
