Java-15.7 Map (1)-using arrays to simulate the creation of Map

Source: Internet
Author: User

Java-15.7 Map (1)-using arrays to simulate the creation of Map

In this chapter, we will simulate Map using arrays and learn about the creation of Map.

1. What is Map?

Map, a ing table, also called an association array, maintains the association of "key-value.


2. Simulate Map using Arrays


package com.ray.ch15;import java.util.HashSet;import java.util.Set;public class Test
   {public static void main(String[] args) {AssociativeArray
    map = new AssociativeArray
    (2);map.put("one", "1");map.put("two", "2");try {map.put("three", "3");} catch (Exception e) {System.out.println("too many objects");}for (String key : map.getKeySet()) {System.out.println(map.getByKey(key));}}}class AssociativeArray
      {private Object[][] objects;private int index = 0;public AssociativeArray(int count) {objects = new Object[count][2];}public void put(K key, V value) {if (index >= objects.length) {throw new ArrayIndexOutOfBoundsException();}objects[index++] = new Object[] { key, value };}public Set
       getKeySet() {Set
        set = new HashSet
        ();for (int i = 0; i < objects.length; i++) {set.add((K) objects[i][0]);}return set;}@SuppressWarnings("unchecked")public V getByKey(K key) {V v = null;for (int i = 0; i < objects.length; i++) {if (objects[i][0] == key) {v = (V) objects[i][1];}}return v;}}



Too upload objects


The above Code uses arrays to simulate the creation of Map.


(1) The above uses an Object array as the underlying data storage structure

(2) get method through array assignment

(3) Implement the getKeyset and get methods by traversing the Array


The above code is the simplest implementation, without any optimization, and there are various problems. We will end the implementation of java in the future.

Summary: This chapter describes how to use arrays to simulate the creation of map.

This chapter is here. Thank you.


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