LWUIT リストにレコード数を表示する LWUIT アプリがあります。
getRecordData()すべてのレコードを取得するには、すべてのレコードを String 配列として返すというメソッドを使用しますが、問題なく動作します。
しかし、これらのレコードの数をどのように数えますか?
import java.util.*;
import com.sun.lwuit.events.*;
import javax.microedition.midlet.*;
import com.sun.lwuit.*;
import com.sun.lwuit.plaf.*;
import javax.microedition.rms.RecordStore;
import javax.microedition.rms .*;
public class number_of_records extends MIDlet {
private RecordStore recordStore;
// Refresh2( ) method for getting the time now
public String Refresh2()
{
java.util.Calendar calendar = java.util.Calendar.getInstance();
Date myDate = new Date();
calendar.setTime(myDate);
StringBuffer time = new StringBuffer();
time.append(calendar.get(java.util.Calendar.HOUR_OF_DAY)).append(':');
time.append(calendar.get(java.util.Calendar.MINUTE)) ;
// time.append(calendar.get(java.util.Calendar.SECOND));
String tt = time.toString();
return tt;
}
// return all records of recordStore RecordStore
public String [] getRecordData( )
{
String[] str = null;
int counter = 0;
try
{
RecordEnumeration enumeration = recordStore.enumerateRecords(null, null, false);
str = new String[recordStore.getNumRecords()];
while(enumeration.hasNextElement())
{
try
{
str[counter] = (new String(enumeration.nextRecord()));
counter ++;
}
catch(javax.microedition.rms.RecordStoreException e)
{
}
}
}
catch(javax.microedition.rms.RecordStoreNotOpenException e)
{
}
catch(java.lang.NullPointerException n)
{
}
return str;
}
public void startApp()
{
com.sun.lwuit.Display.init(this);
final Button addition = new Button("add a goal");
final com.sun.lwuit.TextField tf = new com.sun.lwuit.TextField();
final com.sun.lwuit.List mylist = new com.sun.lwuit.List();
final Button All = new Button("All Goals");
final com.sun.lwuit.Form ff = new com.sun.lwuit.Form();
final com.sun.lwuit.Form g = new com.sun.lwuit.Form();
ff.getStyle().setBgColor(0X99CCFF);
All.getStyle().setBgColor(0X0066CC);
Style g_style5 = g.getSelectedStyle() ;
g.addComponent(tf);
g.addComponent(addition);
addition.getStyle().setBgColor(0X0066CC);
g.addComponent(All);
g.getStyle().setBgColor(0X99CCFF);
addition.addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent ae)
{
//
String s =tf.getText();
if( s!=null && s.length() > 0)
{
try
{
// Store the time in the String k
String k = Refresh2();
// The record and the time stored in KK String
String kk =tf.getText()+"-"+k;
// Add an item (the kk String) to mylist List.
mylist.addItem(kk);
byte bytestream[] = kk.getBytes() ;
// Add a record to recordStore.
int i = recordStore.addRecord(bytestream, 0, bytestream.length);
}
catch(Exception ex) { }
// Inform the User that he added the a record.
Dialog validDialog = new Dialog(" ");
Style Dialogstyle = validDialog.getSelectedStyle() ;
validDialog.setScrollable(false);
validDialog.getDialogStyle().setBgColor(0x0066CC);
validDialog.setTimeout(1000); // set timeout milliseconds
TextArea textArea = new TextArea("...."); //pass the alert text here
textArea.setFocusable(false);
textArea.setText("A goal has been added"+"" );
validDialog.addComponent(textArea);
validDialog.show(0, 10, 10, 10, true);
}
// Information to user that he/she didn’t add a record
else if((s==null || s.length()<= 0))
{
Dialog validDialo = new Dialog(" ");
validDialo.setScrollable(false);
validDialo.getDialogStyle().setBgColor(0x0066CC);
validDialo.setTimeout(5000); // set timeout milliseconds
TextArea textArea = new TextArea("...."); //pass the alert text here
textArea.setFocusable(false);
textArea.setText("please enter scorer name or number");
validDialo.addComponent(textArea);
validDialo.show(50, 50, 50, 50, true);
}
}
});
/*Action here for displaying all records of recordStore RecordStore in a new form */
All.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent ae) {
try
{
recordStore = RecordStore.openRecordStore("My Record Store", true);
}
catch(Exception ex) {}
try
{
com.sun.lwuit.Label l = new com.sun.lwuit.Label(" Team Goals") ;
ff.addComponent(l);
// Store the records of recordStore in string array
String [] record= getRecordData();
int j1;
String valueToBeInserted2="";
int k=getRecordData().length;
for( j1=0;j1< getRecordData().length;j1++)
{
valueToBeInserted2=valueToBeInserted2 + " " + record[j1];
if(j1==getRecordData().length)
{
mylist.addItem(record[j1]);
int m = getRecordData().length;
// Counting the number of records
String goals =""+getRecordData().length;
/* I tried to use for…loop to count them by length of the recordStore and render it.
This list also should display the number of records on the form.
But it didn’t !!!
*/
mylist.addItem(goals);
}
}
ff.addComponent(mylist);
}
catch(java.lang.IllegalArgumentException e)
{
}
finally
{
ff.show();
}
}
}
);
g.show();
}
public void pauseApp()
{
}
public void destroyApp(boolean unconditional) {
}
}
私はこのコードを書きましたが、NullPointerException at recordStore.enumerateRecords (null, null,true);
そこで、ここで問題だと思います。
助けてください。
myButton.addActionListener( new ActionListener()
{
public void actionPerformed(ActionEvet av)
{
try
{
RecordEnumeration enumeration = recordStore.enumerateRecords (null, null,true);
int o =recordStore.getNumRecords () ;
}
catch(Exception e)
{
}
}
});