listcompare_midlet.java

《J2ME无线移动游戏开发》一书的配套光盘

package ch12;

import javax.microedition.midlet.*;
import javax.microedition.rms.*;

public class ListCompare_MIDlet
    extends MIDlet
    implements RecordComparator {

  private RecordStore rs = null;
  private RecordEnumeration re = null;
  public ListCompare_MIDlet() {
    try {
      rs.deleteRecordStore("test");
      rs = RecordStore.openRecordStore("test", true);
      byte[] data = "firstrecord".getBytes();
      rs.addRecord(data, 0, data.length);
      data = "secondlyrecord".getBytes();
      rs.addRecord(data, 0, data.length);
      data = "thirdrecord".getBytes();
      rs.addRecord(data, 0, data.length);
      data = "fourthrecord".getBytes();
      rs.addRecord(data, 0, data.length);

      re = rs.enumerateRecords(null, this, false);
      System.out.println("按字母字典顺序排列的记录如下：");
      while (re.hasNextElement()) {
        try {
          int j = re.nextRecordId();
          data = rs.getRecord(j);
          System.out.println("记录ID号为" + j + "的记录:" + new String(data));
        }
        catch (Exception e) {
          System.out.println(e.getMessage());
        }
      }
    }
    catch (RecordStoreNotOpenException rsnoe) {
      System.out.println(rsnoe.getMessage());
    }
    catch (InvalidRecordIDException iride) {
      System.out.println(iride.getMessage());
    }
    catch (RecordStoreException rse) {
      System.out.println(rse.getMessage());
    }

  }

  public int compare(byte[] rec1, byte[] rec2) {

    for (int i = 0; (i < rec1.length) && (i < rec2.length); i++) {
      if (rec1[i] < rec2[i]) {
        return Record_Comparator.PRECEDES;
      }
      if (rec1[i] > rec2[i]) {
        return Record_Comparator.FOLLOWS;
      }
    }
    return Record_Comparator.EQUIVALENT;
  }

  public void startApp() {

  }

  public void pauseApp() {
  }

  public void destroyApp(boolean unconditional) {
    try {
      if (rs != null) {
        rs.closeRecordStore();
      }
    }
    catch (RecordStoreException rse) {
      System.out.println(rse.getMessage());
    }
  }
}