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Copy pathLinkedHashMapCustom.java
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192 lines (171 loc) · 5.19 KB
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package Maps;
public class LinkedHashMapCustom<K, V> {
private final int DEFAULT_CAPACITY = 17;
private Entry previous = null;
private final Entry[] bucket = new Entry[DEFAULT_CAPACITY];
private Entry root = null;
private int size = 0;
private class Entry<K, V> {
K key;
V val;
Entry next;
Entry after;
Entry before;
public Entry(K key, V val, Entry next, Entry after, Entry before) {
this.key = key;
this.val = val;
this.next = next;
this.after = after;
this.before = before;
}
}
private int hashCode(K key) {
return key.hashCode() % bucket.length;
}
public boolean put(K key, V val) {
int hash = hashCode(key);
if (root == null) {
root = new Entry<>(key, val, null, null, null);
previous = root;
bucket[hash] = root;
size++;
return true;
}
Entry<K, V> temp = bucket[hash];
if (temp == null) {
bucket[hash] = new Entry<>(key, val, null, null, previous);
previous.after = bucket[hash];
previous = bucket[hash];
size++;
return true;
}
while (temp.next != null) {
if (temp.key.equals(key)) {
temp.val = val;
return true;
}
temp = temp.next;
}
if (temp.key.equals(key)) {
temp.val = val;
return true;
}
temp.next = new Entry<>(key, val, null, null, previous);
previous.after = temp.next;
previous = temp.next;
size++;
return true;
}
public V get(K key) {
int hash = hashCode(key);
if (bucket[hash] == null) {
return null;
}
Entry temp = bucket[hash];
while (temp != null) {
if (temp.key.equals(key)) {
return (V) temp.val;
}
temp = temp.next;
}
return null;
}
public boolean containsKey(K key) {
return get(key) != null;
}
public boolean containsValue(V val) {
Entry temp = root;
while (temp != null) {
if (temp.val.equals(val)) {
return true;
}
temp = temp.after;
}
return false;
}
public V remove(K key) throws Exception {
int hash = hashCode(key);
Entry temp = bucket[hash];
if (temp.key.equals(key)) {
V retval = (V) temp.val;
if (temp == root) {
root = temp.after;
}
if (temp.before != null) {
temp.before.after = temp.after;
}
if (temp.after != null) {
temp.after.before = temp.before;
}
bucket[hash] = temp.next;
size--;
return retval;
} else {
while (temp.next != null) {
if (temp.next.key.equals(key)) {
break;
}
temp = temp.next;
}
if (temp != null) {
Entry delete = temp.next;
if (delete == null) {
// you can remove exception if you dont want and replace it it return
throw new Exception("No such element exception");
//return;
}
if (delete.before != null) {
delete.before.after = delete.after != null ? delete.after : null;
}
if (delete.after != null) {
delete.after.before = delete.before != null ? delete.before : null;
}
temp.next = temp.next.next;
size--;
return (V) delete.val;
}
return null;
}
}
public V getOrDefault(K key, V defaultValue) {
V value = get(key);
if (value == null) {
return defaultValue;
}
return value;
}
public void clear() {
root = null;
previous = null;
for (int i = 0; i < bucket.length; i++) {
bucket[i] = null;
}
}
@Override
public String toString() {
Entry<K, V> temp = root;
StringBuilder builder = new StringBuilder("{");
while (temp != null) {
builder.append(temp.key + "=" + temp.val + ",");
temp = temp.after;
}
if(builder.length()==1) builder.append(" ");
String t = builder.substring(0, builder.length() - 1);
return new StringBuilder(t).append("}").toString();
}
public int size() {
return size;
}
public Object[] toKeyArray() {
Object[] t = new Object[size()];
int j = 0;
Entry temp = root;
while (temp != null) {
t[j++] = temp.key;
temp = temp.after;
}
return t;
}
}
// check out the structure of LinkedHashMap image to understand more better
//https://lh4.googleusercontent.com/5M89iub9wNrKR-jmctcmLtGIHiy0lbqL5Oz18AvQyuHdFXGDC4qKgCVZO73WPujj3qqquh_WXlKp7zem4vCfEynJzcN-t0a_wa_mSxDO62G2C-YgEvUhQRBdXdWvpBIhDDM0BxE