Preferences.java

import java.util.*;
import javax.microedition.rms.*;

public class Preferences {

    private String mRecordStoreName;
    private Hashtable mHashtable;

    public Preferences(String recordStoreName)
            throws RecordStoreException {
        mRecordStoreName = recordStoreName;
        mHashtable = new Hashtable();
        load();
    }

    public String get(String key) {
        return (String) mHashtable.get(key);
    }

    public void put(String key, String value) {
        if (value == null) {
            value = "";
        }
        mHashtable.put(key, value);
    }

    private void load() throws RecordStoreException {
        RecordStore rs = null;
        RecordEnumeration re = null;

        try {
            rs = RecordStore.openRecordStore(mRecordStoreName, true);
            re = rs.enumerateRecords(null, null, false);
            while (re.hasNextElement()) {
                byte[] raw = re.nextRecord();
                String pref = new String(raw);
                // Parse out the name.
                int index = pref.indexOf('|');
                String name = pref.substring(0, index);
                String value = pref.substring(index + 1);
                put(name, value);
            }
        } finally {
            if (re != null) {
                re.destroy();
            }
            if (rs != null) {
                rs.closeRecordStore();
            }
        }
    }

    public void save() throws RecordStoreException {
        RecordStore rs = null;
        RecordEnumeration re = null;
        try {
            rs = RecordStore.openRecordStore(mRecordStoreName, true);
            re = rs.enumerateRecords(null, null, false);

            // First remove all records, a little clumsy.
            while (re.hasNextElement()) {
                int id = re.nextRecordId();
                rs.deleteRecord(id);
            }

            // Now save the preferences records.
            Enumeration keys = mHashtable.keys();
            while (keys.hasMoreElements()) {
                String key = (String) keys.nextElement();
                String value = get(key);
                String pref = key + "|" + value;
                byte[] raw = pref.getBytes();
                rs.addRecord(raw, 0, raw.length);
            }
        } finally {
            if (re != null) {
                re.destroy();
            }
            if (rs != null) {
                rs.closeRecordStore();
            }
        }
    }
}