Java dynamic set framework guide
Java dynamic set framework guide
The Java dynamic set framework is an important part of the Java programming language. It provides a set of flexible and efficient data structures for storage and operation data.This article will introduce the concept of the Java dynamic set framework and how to use it to solve common programming problems.
The Java dynamic set framework includes the following main classes: List (list), set (set) and MAP (mapping).These classes are based on interface definitions, so different implementation classes can be selected according to actual needs.
1. List (list):
The list is an orderly collection that can contain duplicate elements.Common implementation classes include ArrayList and LinkedList.ArrayList is a dynamic array that can automatically increase or reduce the capacity as needed.LinkedList is a dual chain list that can efficiently insert and delete the element.The following is an example code to demonstrate how to create and operate an arrayList:
import java.util.ArrayList;
import java.util.List;
public class ArrayListExample {
public static void main(String[] args) {
List<String> fruits = new ArrayList<>();
// Add elements
fruits.add ("Apple");
fruits.add ("Banana");
fruits.add ("Orange");
// Get elements
String firstFruit = fruits.get(0);
System.out.println ("The first fruit is:" + firstfruit);
// Traversing elements
for (String fruit : fruits) {
System.out.println(fruit);
}
// Delete elements
fruits.remove ("Banana");
System.out.println ("" Fruit list after deleted: " + FRUITS);
}
}
2. Collection (set):
Collection is a container that does not allow duplicate elements.Common implementation classes include Hashset and TreeSet.Hashset uses hash tables to store elements, which can quickly find and insert.TreeSet uses red and black trees to store elements, which can be sorted in the natural order of the element.The following is a sample code to demonstrate how to create and operate a hashset:
import java.util.HashSet;
import java.util.Set;
public class HashSetExample {
public static void main(String[] args) {
Set<String> colors = new HashSet<>();
// Add elements
Colors.add ("Red");
colrs.add ("green");
colors.add ("blue");
// Determine whether the element exists
boolean containsRed = colors.contains("红色");
System.out.println ("Whether it contains red:" + containsred);
// Traversing elements
for (String color : colors) {
System.out.println(color);
}
// Delete elements
Colors.remove ("Green");
System.out.println ("The color collection after deleted:" + colors);
}
}
3. Map (MAP):
The mapping is a collection of key value pairs, and each key is associated with a unique value.Common implementation classes include HashMap and TreeMap.HashMap uses the hash table to achieve mapping, which can quickly find and insert.TREEMAP uses red and black trees to store key values pairs, and can be sorted in the natural order of the key.The following is an example code to demonstrate how to create and operate a hashmap:
import java.util.HashMap;
import java.util.Map;
public class HashMapExample {
public static void main(String[] args) {
Map<String, Integer> scores = new HashMap<>();
// Add mapping relationship
scores.put ("Xiaoming", 90);
scores.put ("Little Red", 80);
scores.put ("Xiaogang", 85);
// Get the value
int scoreofxiaoming = scores.get ("Xiaoming");
System.out.println ("Xiaoming's results:" + scoreofxiaoming);
// Traversing key value pair
for (Map.Entry<String, Integer> entry : scores.entrySet()) {
String name = entry.getKey();
int score = entry.getValue();
System.out.println (name + "results are:" + score);
}
// Delete the mapping relationship
scores.remove ("Little Red");
System.out.println ("Deleted transcripts:" + scores);
}
}
The above is a brief introduction and use guide for the Java dynamic set framework.By flexibly using lists, sets, and mapping, we can handle and operate data more conveniently.In actual programming, select a suitable collection class according to specific needs, which can improve the performance and maintenance of the program.
