手写实现一个简单的hashmap

package t1;

public class Test<K, V> {

private Entry[] table;
private static final int CAPCITY = 2;

public void put(K k, V v) {
if (table == null) {
init();
}
int hashCode = hash(k);
int index = indexFor(hashCode);

for (Entry entry = table[index]; entry != null; entry = entry.next) {
if (entry.key == k) {
entry.value = v;
break;
}
}

addEntry(k, v, index);
}

private void addEntry(K k, V v, int index) {
Entry newEntry = new Entry(k, v, table[index]);
table[index] = newEntry;
}

private int indexFor(int hashCode) {
return hashCode % table.length;
}

private int hash(K k) {
return k.hashCode();
}

@SuppressWarnings("unchecked")
private void init() {
table = new Test.Entry[CAPCITY];
}

public V get(K k) {
int hashCode = hash(k);
int index = indexFor(hashCode);
for (Entry entry = table[index]; entry != null; entry = entry.next) {
if (entry.key == k) {
return entry.value;
}
}
return null;
}

class Entry {
public K key;
public V value;
public Entry next;

public Entry(K key, V value) {
super();
this.key = key;
this.value = value;
}

public Entry(K key, V value, Test<K, V>.Entry next) {
super();
this.key = key;
this.value = value;
this.next = next;
}

@Override
public String toString() {
return "Entry [key=" + key + ", value=" + value + ", next=" + next + "]";
}

public K getKey() {
return key;
}

public void setKey(K key) {
this.key = key;
}

public V getValue() {
return value;
}

public void setValue(V value) {
this.value = value;
}

public Entry getNext() {
return next;
}

public void setNext(Entry next) {
this.next = next;
}

}

public static void main(String[] args) {
Test<String, String> myHashMap = new Test<>();
myHashMap.put("1", "1v");
myHashMap.put("2", "2v");
myHashMap.put("3", "3v");
myHashMap.put("4", "4v");
myHashMap.put("1", "5v");
System.out.println(myHashMap.get("1"));
}
}

 

输出结果：