CareerCup

class Entry<K, V> {
K key;
V val;

public K getKey() {
return key;
}

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

public V getVal() {
return val;
}

public void setVal(V val) {
this.val = val;
}

@Override
public int hashCode() {
int prime = 13;
int mul = 11;
if (key != null) {
int hashCode = prime * mul + key.hashCode();
return hashCode;
}
return 0;
}

@Override
public boolean equals(Object o) {
if (this == o) {
return true;
}
if (o == null || this.getClass().getName() != o.getClass().getName()) {
return false;
}
Entry e = (Entry) o;
if (this.key == e.key) {
return true;
}
return false;
}
}

public class HashMapImpl<K, V> {
private float loadfactor = 0.75f;
private int capacity = 100;
private int size = 0;
private Entry<K, V> table[] = new Entry[capacity];

private int Hashing(int hashCode) {
int location = hashCode % capacity;
System.out.println("Location:"+location);
return location;
}

public int size() {
// TODO Auto-generated method stub
return this.size;
}

public boolean isEmpty() {
if(this.size == 0) {
return true;
}
return false;
}

public boolean containsKey(Object key) {
if(key == null) {
if(table[0].getKey() == null) {
return true;
}
}
int location = Hashing(key.hashCode());
Entry e = null;
try {
e = table[location];
}catch(NullPointerException ex) {

}
if(e!= null && e.getKey() == key) {
return true;
}
return false;
}

public boolean containsValue(Object value) {
for(int i=0; i<table.length;i++) {
if(table[i] != null && table[i].getVal() == value) {
return true;
}
}
return false;
}

public V get(K key) {
V ret = null;
if(key == null) {
Entry<K, V> e = null;
try{
e = table[0];
}catch(NullPointerException ex) {

}
if(e != null) {
return (V) e.getVal();
}
} else {
int location = Hashing(key.hashCode());
Entry<K, V> e = null;
try{
e = table[location];
}catch(NullPointerException ex) {

}
if(e!= null && e.getKey() == key) {
return (V)e.getVal();
}
}
return ret;
}

public V put(K key, V val) {
V ret = null;
if (key == null) {
ret = putForNullKey(val);
return ret;
} else {
int location = Hashing(key.hashCode());
if(location >= capacity) {
System.out.println("Rehashing required");
return null;
}
Entry<K, V> e = null;
try{
e = table[location];
}catch(NullPointerException ex) {

}
if (e!= null && e.getKey() == key) {
ret = (V) e.getVal();
} else {
Entry<K, V> eNew = new Entry<K,V>();
eNew.setKey(key);
eNew.setVal(val);
table[location] = eNew;
size++;
}
}
return ret;
}

private V putForNullKey(V val) {
Entry<K, V> e = null;
try {
e = table[0];
}catch(NullPointerException ex) {

}
V ret = null;
if (e != null && e.getKey() == null) {
ret = (V) e.getVal();
e.setVal(val);
return ret;
} else {
Entry<K, V> eNew = new Entry<K,V>();
eNew.setKey(null);
eNew.setVal(val);
table[0] = eNew;
size++;
}
return ret;
}

public V remove(K key) {
int location = Hashing(key.hashCode());
V ret = null;
if(table[location].getKey() == key) {
for(int i=location; i<table.length;i++) {
table[i] = table[i+1];
}
}
return ret;
}

public static void main(String[] args) {
HashMapImpl<Integer, String> hashMap = new HashMapImpl<Integer, String>();
hashMap.put(10, "Apple");
hashMap.put(1, "Orange");
hashMap.put(79, "Grape");
System.out.println("Val at 79 "+hashMap.get(79));
System.out.println("Val at 1 "+hashMap.get(1));
System.out.println("Val at 10 "+hashMap.get(10));
System.out.println("Val at 2 "+hashMap.get(2));
hashMap.put(null, "Pear");
System.out.println("Val at null "+hashMap.get(null));
System.out.println("Hashmap has key at null:"+hashMap.containsKey(null));
System.out.println("Hashmap has value at null:"+hashMap.containsValue("Pear"));
System.out.println("Size of Map:"+hashMap.size());
}


}