理解Map-构建关联数组
理解Map
要更深入理解map,学习如何构建关联数组是很有帮助的,以下是简单实现
package org.example.onjava.senior.example03collection.map;
import java.util.Objects;
/**
* @Author Coder_Pans
* @Date 2022/11/21 14:34
* @PackageName:org.example.onjava.senior.example03collection.map
* @ClassName: AssocaiativeArray
* @Description: TODO 实现关联数组
* @Version 1.0
*/
public class AssocaiativeArray<K, V> {
private Object[][] pairs;
private int index;
public AssocaiativeArray(int length) {
pairs = new Object[length][2];
}
public void put(K key, V value) {
if (index >= pairs.length)
throw new ArrayIndexOutOfBoundsException();
pairs[index++] = new Object[]{key, value};
}
@SuppressWarnings("unchecked")
public V get(K key) {
for (int i = 0; i < index; i++)
if (key.equals(pairs[i][0]))
return (V) pairs[i][1];
return null; // Did not find key
}
@Override
public String toString() {
StringBuilder result = new StringBuilder();
for (int i = 0; i < index; i++) {
result.append(pairs[i][0].toString());
result.append(" : ");
result.append(pairs[i][1].toString());
if (i < index - 1)
result.append("\n");
}
return result.toString();
}
public static void main(String[] args) {
AssocaiativeArray<String, String> map =
new AssocaiativeArray<>(6);
map.put("sky", "blue");
map.put("grass", "green");
map.put("ocean", "dancing");
map.put("tree", "tall");
map.put("earth", "brown");
map.put("sun", "warm");
try {
map.put("extra", "object"); // Past the end
} catch (ArrayIndexOutOfBoundsException e) {
System.out.println("Too many objects!");
}
System.out.println(map);
System.out.println(map.get("ocean"));
}
}
关联数组中的基本方法是put和get,但是为了便于显示,我们重写了toString来打印键值对,为了演示其可以工作,我们子啊main中创建了一个由String对组成的AssociativeArray,并打印了生成的映射,之后通过get获取了其中的一个值。
posted on 2022-11-21 15:07 JavaCoderPan 阅读(26) 评论(0) 编辑 收藏 举报