com.darwinsys.util.PropertiesMap Maven / Gradle / Ivy
package com.darwinsys.util;
import java.io.BufferedReader;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Set;
/**
* PropertiesMap -- a Map that loads from a Properties file, but unlike
* Properties, preserves the ordering of the original file.
*
* Written mainly as a demonstration of building a simple Map implementation
* from scratch, but useful when order matters and yet you want the
* convenience of Map acccess.
* @author Ian F. Darwin
*/
public class PropertiesMap implements Map {
private List names = new ArrayList();
private List values = new ArrayList();
public void load(String fileName) throws IOException {
if (fileName == null) {
throw new IOException("filename is null!");
}
InputStream is = new FileInputStream(fileName);
BufferedReader rdr = new BufferedReader(
new InputStreamReader(is));
String line;
while ((line = rdr.readLine()) != null) {
int ix = line.indexOf('=');
String name = line.substring(0, ix);
String value = line.substring(ix+1);
names.add(name);
values.add(value);
}
rdr.close();
}
/** Return the number of entries in the Map */
public int size() {
return names.size();
}
/** Return true if the Map is empty */
public boolean isEmpty() {
return names.isEmpty();
}
/** Return true if the given object is contained as a Key */
public boolean containsKey(Object obj) {
return names.contains(obj);
}
/** Return true if the given object is contained as a Value */
public boolean containsValue(Object obj) {
return values.contains(obj);
}
/** Get a given object */
public String get(Object obj) {
int where = names.indexOf(obj);
if (where == -1) {
return null;
}
return values.get(where);
}
/** Add a given object into this Map. */
public String put(String n, String v) {
names.add(n);
values.add(v);
return n;
}
/** Remove a given object */
public String remove(Object obj) {
String o = obj.toString();
int i = values.indexOf(o);
if (i < 0)
throw new IllegalArgumentException("remove(" + obj + ") not found");
names.remove(i);
values.remove(i);
return o;
}
/** Merge all the values from another map into this map. */
@SuppressWarnings("unchecked")
public void putAll(Map map) {
Iterator k = map.entrySet().iterator();
while (k.hasNext()) {
Map.Entry e = k.next();
String key = e.getKey();
String val = e.getValue();
put(key, val);
}
}
/** Discard all object references held in the collection, i.e.,
* reset to its initial state.
*/
public void clear() {
names.clear();
values.clear();
}
/** Return the set of keys */
public java.util.Set keySet() {
return new HashSet(names);
}
/** Return a Collection containing the values */
public java.util.Collection values() {
return values;
}
/** EntrySet (not implemented, returns null) */
public Set> entrySet() {
return null;
}
}