Mega Code Archive
Extends AbstractMap
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/*
Output:
{Virginia=Richmond, Massachusetts=Boston, New York=Albany}
[Virginia, Massachusetts, New York]
[Richmond, Boston, Albany]
* */
import java.io.Serializable;
import java.util.AbstractMap;
import java.util.AbstractSet;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;
public class MainClass {
public static void main (String args[]) {
Map map = new ArrayMap(13);
map.put("Virginia", "Richmond");
map.put("Massachusetts", "Boston");
map.put("New York", "Albany");
System.out.println(map);
System.out.println(map.keySet());
System.out.println(map.values());
}
}
class ArrayMap extends AbstractMap implements Cloneable, Serializable {
static class Entry implements Map.Entry {
protected Object key, value;
public Entry(Object key, Object value) {
this.key = key;
this.value = value;
}
public Object getKey() {
return key;
}
public Object getValue() {
return value;
}
public Object setValue(Object newValue) {
Object oldValue = value;
value = newValue;
return oldValue;
}
public boolean equals(Object o) {
if (!(o instanceof Map.Entry)) {
return false;
}
Map.Entry e = (Map.Entry) o;
return (key == null ? e.getKey() == null : key.equals(e.getKey()))
&& (value == null ? e.getValue() == null : value.equals(e.getValue()));
}
public int hashCode() {
int keyHash = (key == null ? 0 : key.hashCode());
int valueHash = (value == null ? 0 : value.hashCode());
return keyHash ^ valueHash;
}
public String toString() {
return key + "=" + value;
}
}
private Set entries = null;
private ArrayList list;
public ArrayMap() {
list = new ArrayList();
}
public ArrayMap(Map map) {
list = new ArrayList();
putAll(map);
}
public ArrayMap(int initialCapacity) {
list = new ArrayList(initialCapacity);
}
public Set entrySet() {
if (entries == null) {
entries = new AbstractSet() {
public void clear() {
list.clear();
}
public Iterator iterator() {
return list.iterator();
}
public int size() {
return list.size();
}
};
}
return entries;
}
public Object put(Object key, Object value) {
int size = list.size();
Entry entry = null;
int i;
if (key == null) {
for (i = 0; i < size; i++) {
entry = (Entry) (list.get(i));
if (entry.getKey() == null) {
break;
}
}
} else {
for (i = 0; i < size; i++) {
entry = (Entry) (list.get(i));
if (key.equals(entry.getKey())) {
break;
}
}
}
Object oldValue = null;
if (i < size) {
oldValue = entry.getValue();
entry.setValue(value);
} else {
list.add(new Entry(key, value));
}
return oldValue;
}
public Object clone() {
return new ArrayMap(this);
}
}
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