I'm developing a j2me application based on codenameone. I implements some codes and Now I wanna add database to my application. After search a lot I found Storage class of codenameone that simplify database concept in mobile application.
In this appliaction I create a class for each entity (like person, city, ...) and add "read" and "write" method to read and write data.
Some entity classes have 2 or more fields. So I must save and read them with Storage class.
How can I do this?
Here is my sample code:
package com.x.database;
import com.codename1.io.Storage;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Hashtable;
import java.util.Iterator;
public class Person {
public Person(){
}
public Person(int pID, String pPersonNumber){
ID = pID;
PersonNumber = pPersonNumber;
}
public static String PERSON = "Person";
private Storage store;
private int ID;
public int getID(){
return ID;
}
public void setID(int pID){
ID = pID;
}
private String PersonNumber;
public String getPersonNumber(){
return PersonNumber;
}
public void setPersonNumber(String pPersonNumber){
PersonNumber = pPersonNumber;
}
public int getLastKeyNumber(){
if(store == null) {
store = Storage.getInstance();
}
Hashtable depHash = (Hashtable)store.readObject(PERSON);
ArrayList<String> keyArray = (ArrayList<String>)depHash.keys();
int i = 0;
for (Iterator<String> it = keyArray.iterator(); it.hasNext();) {
int tmp = Integer.parseInt(it.next());
i = i < tmp ? tmp : i;
}
return i;
}
public void write(Person pPerson){
if(store == null) {
store = Storage.getInstance();
}
if(!store.exists(PERSON)) {
Hashtable depHash = new Hashtable();
try {
depHash.put("0", pPerson);
} catch (IOException ex) {
System.out.println(ex.getMessage());
}
store.writeObject(PERSON, depHash);
}
else {
Hashtable depHash = (Hashtable)store.readObject(PERSON);
ArrayList<Person> depArray = (ArrayList<Person>)depHash.keys();
for (Iterator<Person> it = depArray.iterator(); it.hasNext();) {
Person tmp = it.next();
if(!tmp.getPersonNumber().equals(pPerson)) {
depHash.put(String.valueOf(getLastKeyNumber()), pPerson.getPersonNumber());
store.writeObject(Person depHash);
}
}
}
}
public ArrayList<Person> readAll(){
Storage store = Storage.getInstance();
if(!store.exists(PERSON)) {
Hashtable depHash = (Hashtable)store.readObject(PERSON);
return (ArrayList<Person>)depHash.elements();
}
return new ArrayList<Person>();
}
}
In this code I have an error on write and read object on Storage.
How can I write one object in Storage and read it again?
Thanks in advance.
You can store a Vector or a Hashtable in storage and nest them as deeply as you like e.g.:
Vector v = new Vector();
Hashtable content = new Hashtable();
content.put("A", ...);
content.put("B", ...);
v.addElement(content);
Etc... You can add more hashes and they can contain Strings, numbers or byte arrays.
Alternatively you can implement the Codename One Externalizable interface which allows you to write an arbitrary class to storage. This poses one requirement though, you need to call Util.register in order to register the externalizable class name. There is a sample of this in the tipster demo.
Related
I am working on different approaches of cloning of an objects in c# but currently I stuck with the simple one. I have a static class with static variables & I want to make an exact copy of one of my static variable.I have sketched my code structure below:
public static class RULE_SET
{
public static bool IsdataValid;
public static GCBRequest GCBData;
public static T Clone<T>(this T source)
{
try
{
if (!typeof(T).IsSerializable)
{
throw new ArgumentException("The type must be serializable.", "source");
}
if (Object.ReferenceEquals(source, null))
{
return default(T);
}
IFormatter formatter = new BinaryFormatter();
Stream stream = new MemoryStream();
using (stream)
{
formatter.Serialize(stream, source);
stream.Seek(0, SeekOrigin.Begin);
return (T)formatter.Deserialize(stream);
}
}
catch (Exception ee) { return default(T); }
}
}
[XmlRoot(ElementName = "GCBRequest")]
public class GCBRequest
{
[XmlElement(ElementName = "PID")]
public string PID { get; set; }
[XmlElement(ElementName = "AID")]
public string AID { get; set; }
[XmlElement(ElementName = "CID")]
public string CID { get; set; }
}
//code to load the RULE_SET
string strJsonRuleset = "{\r\n \"GCdBINRequest\": {\r\n\"PID\": \"(?s).*#M#20\",\r\n\"AID\": \"(?s).*#O#10\",\r\n\"CID\": \"(?s).*#O#25\"\r\n }\r\n}";
public class RULE_SET_LOCAL
{
public static GCBRequest GCBData;
}
//from other method
RULE_SET_LOCAL objParentRuleSet = new RULE_SET_LOCAL();
objParentRuleSet = JsonConvert.DeserializeObject<RULE_SET_LOCAL>(strJsonRuleset);
RULE_SET.GCBData = objParentRuleSet.GCBData;
//Main Method from which I have to create a clone object
Object objRuleset;
objRuleset = RULE_SET.GCBData.Clone();
if(objRuleset == null)
{
** stuck here**
I don't know why Everytime I got the null object ?
}
// but I have use
objRuleset = RULE_SET.GCBData;
if(objRuleset != null)
{
** Successfully reached **
//But I can't do any operation on this object as it will effect the original one.
}
Guys, Do you have any solution/Suggestion ?
Please help me to understand this , any help will be appreciated.
Thanks.
After searching a lot I got this method :
public static T Clone<T>(this T source)
{
var serialized = JsonConvert.SerializeObject(source);
return JsonConvert.DeserializeObject<T>(serialized);
}
& now I am able to get the clone by calling
object objRuleset = RULE_SET.Clone<GCBRequest>(RULE_SET.GCBData);
I am working with two helper classes (Student, Helper), as well as a main class.
In the Student class, I have the following constructor:
Student(String iName, String iMajor, int iNumber) {
name = iName;
major = iMajor;
number = iNumber;
}
In the Helper class, I declare a HashMap as follows:
HashMap<String, Student> students = new HashMap<String, Student>();
Now, I have written a few method for adding (put) new students into the HashMap construction, as well as a method for retrieving information about a student based on the name.
//Adding new students
Student s1 = new Student("Alex", "Biology", 19);
Student s2 = new Student("Brian", "Chemistry", 20);
Student s3 = new Student("Tom", "Biology", 20);
//etc...
//Get student from name (key)
public Student getFromKey(String key) {
return students.get(key);
}
I am now looking to write a method that finds all students based on either major or number. For instance, the call:
helper.getStudents("Biology");
Should return all the students studying Biology. I imagine the method looking something like:
public Student getStudents(String searchItem) {
for(Students st : students.values()) {
if(searchItem.equals(??)) {
return st;
//Something like this.
However, I can't seem to figure out how to access these values. All the classes have appropriate getter and setter methods, and the program works fine. Any help is highly appreciated!
Assuming this Map exists:
HashMap<String, Student> students = new HashMap<String, Student>();
The following would work:
public Student getStudents(String searchItem) {
for(Map.Entry<String,Student> entry : students.entrySet()) {
Student student = entry.getValue();
//perform conditional logic here
}
Here is a more complete example in case you need it:
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
public class Student {
private String name;
private String major;
private int number;
public Student(String name, String major, int number) {
super();
this.name = name;
this.major = major;
this.number = number;
}
public static void main(String[] args) {
List<String> names = Arrays.asList("Joe", "Jack", "John","James");
List<String> majors = Arrays.asList("English","Math","Geography");
Map<String,Student> students = new HashMap<String,Student>();
for(int i = 0; i < 100; i++){
Collections.shuffle(names);
Collections.shuffle(majors);
students.put(names.get(0) + String.valueOf(i), new Student(names.get(0), majors.get(0), i));
}
List<Student> mathMajors = getStudents(students, "Math");
for(Student student:mathMajors){
System.out.println(student.name);
System.out.println(student.major);
}
}
public static List<Student> getStudents(Map<String,Student> students, String searchToken){
List<Student> results = new ArrayList<Student>();
for(Entry<String,Student> entry:students.entrySet()){
if(entry.getValue().getMajor().equalsIgnoreCase(searchToken)){
results.add(entry.getValue());
}
}
return results;
}
public String getName() {
return this.name;
}
public void setName(String name) {
this.name = name;
}
public String getMajor() {
return this.major;
}
public void setMajor(String major) {
this.major = major;
}
public int getNumber() {
return this.number;
}
public void setNumber(int number) {
this.number = number;
}
}
On Github
I want to create an custom appender using log4j in java programatically which stores the log in memory(Certain size will be defined for e.g. say DEFAULT_SIZE=20) & as soon as memory is full(there are 20 logs in memory) create an json array of those logs and send it to the server. Along with log message i also want information such as (class, file name,line number,method name,level etc.)
Help is appreciated.!!!
Updated ::
Below is the source code developed by me for the same . Problem which i am facing is i get line number, method name,file name as "?".I dont understand what is the reason.
package com.any.logger;
import java.util.ArrayList;
import org.apache.log4j.AppenderSkeleton;
import org.apache.log4j.spi.LoggingEvent;
public class Log4jAppender extends AppenderSkeleton {
private static final int DEFAULT_BUFFER_SIZE = 20;
private ArrayList<LoggingEvent> buffer;
private int bufferSize;
public Log4jAppender() {
this.bufferSize = Log4jAppender.DEFAULT_BUFFER_SIZE;
this.buffer = new ArrayList<LoggingEvent>();
}
public void close() {
}
public boolean requiresLayout() {
return false;
}
#Override
protected void append(LoggingEvent loggingEvent) {
synchronized (buffer) {
if (buffer.size() >= bufferSize) {
try {
System.out.println("Hello");
Log4jService service = new Log4jService(new ArrayList<LoggingEvent>
(buffer));
System.out.println("Buff >");
service.start();
} catch (Exception e) {
System.err.println("Failed to write logs");
e.printStackTrace();
} finally {
buffer.clear();
}
}
}
buffer.add(loggingEvent);
}
}
package com.any.logger;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Iterator;
import org.apache.log4j.Level;
import org.apache.log4j.spi.LoggingEvent;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
#SuppressWarnings("rawtypes")
public class Log4jService implements Runnable {
private ArrayList<LoggingEvent> buffer;
private Thread t;
private boolean flag;
public Log4jService(ArrayList<LoggingEvent> buffer) {
this.buffer = new ArrayList<LoggingEvent>(buffer);
this.flag = false;
}
public void start() {
if (!flag) {
this.flag = true;
this.t = new Thread(this);
this.t.start();
}
}
public void run() {
if (flag) {
String json = getLogJson(buffer);
}
}
/**
* Method to get the json log
*
* #param logEvents
* arrayList of log events
* #return an String which is json file
* #throws JSONException
*/
private String getLogJson(ArrayList<LoggingEvent> logEvents) {
System.out.println("In getLogJson");
JSONObject logger = new JSONObject();
try {
JSONArray logs = new JSONArray();
String message = "";
String time = "";
String level = "";
String tag = "";
String file = "";
String exceptionName = "";
String exceptionReason = "";
String line = "";
String clas = "";
String method = "";
int index = 0;
SimpleDateFormat formatter=new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
for (Iterator i = logEvents.iterator(); i.hasNext();) {
LoggingEvent logEvent = (LoggingEvent) i.next();
boolean chk=logEvent.locationInformationExists();
System.out.println("Check :: "+chk);
clas=logEvent.getClass().toString();
JSONObject log = new JSONObject();
message = logEvent.getMessage().toString();
time = String.valueOf(formatter.format(logEvent.getTimeStamp()));
level = logEvent.getLevel().toString();
if (chk) {
System.out.println("hello");
file = logEvent.getLocationInformation().getFileName();
line = logEvent.getLocationInformation().getLineNumber();
method = logEvent.getLocationInformation().getMethodName();
}
if (logEvent.getLevel() == Level.ERROR || logEvent.getLevel() ==
Level.FATAL) {
exceptionReason = message;
}
log.put("message", message);
log.put("time", time);
log.put("level", level);
log.put("tag", tag);
log.put("file", file);
log.put("exceptionName", exceptionName);
log.put("exceptionReason", exceptionReason);
log.put("line", line);
log.put("class", clas);
log.put("method", method);
logs.put(index, log);
index++;
}
JSONObject logsObj = new JSONObject();
logsObj.put("logs", logs);
logger.put("log", logsObj);
System.out.println("Logs Array :: " + logsObj);
System.out.println("Logger Object :: " + logger);
} catch (Exception e) {
e.printStackTrace();
}
return logger.toString();
}
}
I would look at the source code for log4j2 and use an existing appender as a template for my custom appender. SocketAppender and TCPSocketManager may be good places to start.
http://logging.apache.org/log4j/2.0/log4j-core/xref/org/apache/logging/log4j/core/net/TCPSocketManager.html
Currently the buffering is based on the number of bytes, not event count. If you follow the existing appender/manager pattern then in your custom appender manager you will need to have a large enough buffer and flush every 20 events. (Perhaps also flush after some timeout? You may only get 19 events and nothing after that...)
You could also do the buffering in the appender, keep a list of event objects there and only call pass them to the manager to be written after some threshold is reached.
The default Layout for SocketAppender will use java serialization. You'll need to roll your own JasonLayout. The log event object has all the details you mentioned.
I use REST and i was wondering if i can tell jaxb to insert a string field "as-it-is" into the outgoing xml.
Certainly i count unpack it before returning, but i would like to save this step.
#XmlRootElement(name="unnestedResponse")
public class Response{
#Insert annotation here ;-)
private String alreadyXml;
private int otherDate; ...
}
Is there a possability to tell JAXB to just use the String as it is without escapting? I want that the client does not have to parse my response and then parse this field.
greetings,
m
You can use the #XmlAnyElement and specify a DomHandler to keep a portion of the XML document as a String.
Customer
import javax.xml.bind.annotation.*;
#XmlRootElement
public class Customer {
private String bio;
#XmlAnyElement(BioHandler.class)
public String getBio() {
return bio;
}
public void setBio(String bio) {
this.bio = bio;
}
}
BioHandler
import java.io.*;
import javax.xml.bind.ValidationEventHandler;
import javax.xml.bind.annotation.DomHandler;
import javax.xml.transform.Source;
import javax.xml.transform.stream.*;
public class BioHandler implements DomHandler<String, StreamResult> {
private static final String BIO_START_TAG = "<bio>";
private static final String BIO_END_TAG = "</bio>";
private StringWriter xmlWriter = new StringWriter();
public StreamResult createUnmarshaller(ValidationEventHandler errorHandler) {
return new StreamResult(xmlWriter);
}
public String getElement(StreamResult rt) {
String xml = rt.getWriter().toString();
int beginIndex = xml.indexOf(BIO_START_TAG) + BIO_START_TAG.length();
int endIndex = xml.indexOf(BIO_END_TAG);
return xml.substring(beginIndex, endIndex);
}
public Source marshal(String n, ValidationEventHandler errorHandler) {
try {
String xml = BIO_START_TAG + n.trim() + BIO_END_TAG;
StringReader xmlReader = new StringReader(xml);
return new StreamSource(xmlReader);
} catch(Exception e) {
throw new RuntimeException(e);
}
}
}
For More Information
http://blog.bdoughan.com/2011/04/xmlanyelement-and-non-dom-properties.html
Following bdoughan's answer did not work for me as I encountered errors during marshalling when the text contained the '& character (e.g. in URLs or when using HTML entities such as e.g. " ").
I was able to resolve this by changing the custom DomHandler's marshal method to
public Source marshal(String et, ValidationEventHandler veh) {
Node node = new SimpleTextNode(et);
return new DOMSource(node);
}
where SimpleTextNode implements the Node interface as follows:
class SimpleTextNode implements Node {
String nodeValue = "";
#Override
public SimpleTextNode(String nodeValue) {
this.nodeValue = nodeValue;
}
#Override
public short getNodeType() {
return TEXT_NODE;
}
// the remaining methods of the Node interface are not needed during marshalling
// you can just use the code template of your IDE...
...
}
PS: I would have loved to leave this as a comment to bdoughan's answer, but unfortunately I have way too little reputation :-(
I want to store many details (like name, email, country) of the particular person using the same key in hashtable or hashmap in java?
hashMap.put(1, "Programmer");
hashMap.put(2, "IDM");
hashMap.put(3,"Admin");
hashMap.put(4,"HR");
In the above example, the 1st argument is a key and 2nd argument is a value, how can i add more values to the same key?
You can achieve what you're talking about using a map in each location of your map, but it's a little messy.
Map<String, Map> people = new HashMap<String, Map>();
HashMap<String, String> person1 = new HashMap<String, String>();
person1.put("name", "Jones");
person1.put("email", "jones#jones.com");
//etc.
people.put("key", person1);
//...
people.get("key").get("name");
It sounds like what you might really want, though, is to define a Person class that has multiple properties:
class Person
{
private String name;
private String email;
public String getName()
{
return name;
}
public void setName(String name)
{
this.name = name;
}
//plus getters and setters for other properties
}
Map<String, Person> people = new HashMap<String, Person>();
person1 = new Person();
person1.setName("Jones");
people.put("key", person1);
//...
people.get("key").getName();
That's the best I can do without any information about why you're trying to store values in this way. Add more detail to your question if this is barking up the wrong tree.
I think what you are asking
let us assume you we want to store String page, int service in the key and an integer in the value.
Create a class PageService with the required variables and define your HashMap as
Hashmap hmap = .....
Inside pageService, what you need to do is override the equals() and hashcode() methods. Since when hashmap is comparing it checks for hashcode and equals.
Generating hashcode and equals is very easy in IDEs. For example in eclipse go to Source -> generate hashcode() and equals()
public class PageService {
private String page;
private int service;
public PageService(String page, int service) {
super();
this.page = page;
this.service = service;
}
public String getPage() {
return page;
}
public void setPage(String page) {
this.page = page;
}
public int getService() {
return service;
}
public void setService(int service) {
this.service = service;
}
#Override
public int hashCode() {
final int prime = 31;
int result = 1;
result = prime * result + ((page == null) ? 0 : page.hashCode());
result = prime * result + service;
return result;
}
#Override
public boolean equals(Object obj) {
if (this == obj)
return true;
if (obj == null)
return false;
if (getClass() != obj.getClass())
return false;
PageService other = (PageService) obj;
if (page == null) {
if (other.getPage() != null)
return false;
} else if (!page.equals(other.getPage()))
return false;
if (service != other.getService())
return false;
return true;
}
}
The following class is very generic. You can nest ad infinitum. Obviously you can add additional fields and change the types for the HashMap. Also note that the tabbing in the toString method should be smarter. The print out is flat.
import java.util.Collections;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
public class HierarchicalMap
{
private String key;
private String descriptor;
private Map<String,HierarchicalMap>values=new HashMap<String,HierarchicalMap>();
public String getKey()
{
return key;
}
public void setKey(String key)
{
this.key = key;
}
public void addToSubMap(String key, HierarchicalMap subMap)
{
values.put(key, subMap);
}
public String getDescriptor()
{
return descriptor;
}
public void setDescriptor(String descriptor)
{
this.descriptor = descriptor;
}
public HierarchicalMap getFromSubMap(String key)
{
return values.get(key);
}
public Map<String,HierarchicalMap> getUnmodifiableSubMap()
{
return Collections.unmodifiableMap(values);
}
public String toString()
{
StringBuffer sb = new StringBuffer();
sb.append("HierarchicalMap: ");
sb.append(key);
sb.append(" | ");
sb.append(descriptor);
Iterator<String> itr=values.keySet().iterator();
while(itr.hasNext())
{
String key= itr.next();
HierarchicalMap subMap=this.getFromSubMap(key);
sb.append("\n\t");
sb.append(subMap.toString());
}
return sb.toString();
}