更新记录存储j2me中的记录

Question

我想知道j2me中用于更新记录存储中记录的方法。谢谢....

Answer 1

只需使用 RecordStore.setRecord()

Answer 2

在这里尝试这个

Preferences preferences  = new Preferences("ChatAppPref");
preferences.put("login", "y");
preferences.save();
String pIsLogin  = preferences.get("login");

Preferences 类

package com.util;
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();
    }
  }
}