Develop Reference

Java GSON check data

I'm having trouble with gson:
For example I have this output from website:
[["connected"], ["user1":"Hello"], ["user2":"Hey"], ["disconnected"]]
But I want parse this JSON and output something like this:
connected
user1 says: Hello
user2 says: Hey
disconnected
I quicly wrote this code:
public static void PrintEvents(String id){
String response = Post.getResponse(Server()+"events?id="+id,"");
// response is [["connected"],["user1":"Hello"],["user2":"Hey"],["disconnected"]]
JsonElement parse = (new JsonParser()).parse(response); //found this in internet
int bound = ????????????; // Should be 4
for (int i=1;i<=bound;i++){
String data = ???????????;
if (data == "connected" || data == "disconnected") then {
System.out.println(data);
}else if(?????==2){// to check how many strings there is, if it's ["abc","def"] or ["abc"]
String data2 = ??????????????;
System.out.println(data+" says: "+data2);
}else{
//something else
}
};
}
What should I insert to these parts with question marks to make code work?
I cannot find any way to make it work...
Sorry for my bad English.
EDIT: Changed response to [["connected"], ["user1","Hello"], ["user2","Hey"], ["disconnected"]]. Earlier response was not valid JSON.

The response that you have pasted is not a valid json. paste it in http://www.jsoneditoronline.org/ and see the error.
Please find the below code snippet:
public static void printEvents(String id)
{
String response = "[[\"connected\"] ,[\"user1:Hello\"],[\"user2:Hey\"],[\"disconnected\"]]";
JsonElement parse = (new JsonParser()).parse(response); //found this in internet
int bound = ((JsonArray)parse).size(); // Should be 4
for (int i = 0; i < bound; i++) {
String data = ((JsonArray)parse).get(0).getAsString();
if (data.equals("connected") || data.equals("disconnected")) {
System.out.println(data);
continue;
}
String[] splittedData = data.split(":");
if (splittedData.length
== 2) {// to check how many strings there is, if it's ["abc","def"] or ["abc"]
System.out.println(splittedData[0] + " says: " + splittedData[1]);
}
/*
*else{
* your else logic goes here
* }
* */
}
}
Couple of suggestions:
If you are new to json world, use jackson instead of Gson.
the response is not a good design. Slightly correct json:
{
"firstKey": "connected",
"userResponses": [
{
"user1": "hey"
},
{
"user2": "hi"
}
],
"lastKey": "disconnected"
}
Also try to define pojos , instead of working inline with json.

You need to define a separate class like this:
class MyClass{
String name;
String value;
}
and then:
List<MyClass> myclasses = new Gson().fromJson(response, new TypeToken<List<MyClass>>(){}.getType());
then
for(MyClass myclass: myclasses){
...
}

Find and Delete a Sub-String in Java

I'm trying to find a Java sub-string and then delete it without deleting the rest of the string.
I am taking XML as input and would like to delete a deprecated tag, so for instance:
public class whatever {
public static void main(String[] args) {
String uploadedXML = "<someStuff>Bats!</someStuff> <name></name>";
CharSequence deleteRaise = "<name>";
// If an Addenda exists we continue with the process
if (xml_in.contains(deleteRaise)){
// delete
} else {
// Carry on
}
}
In there I would like to delete the <name> and </name> tags if they are included in the string while leaving <someStuff> and </someStuff>.
I already parsed the XML to a String so there's no problem there. I need to know how to find the specific strings and delete them.

You can use replaceAll(regex, str) to do this. If you're not familiar with regex, the ? just means there can be 0 or 1 occurrences of / in the string, so it covers <name> and </name>
String uploadedXML = "<someStuff>Bats!</someStuff> <name></name>";
String filter = "</?name>";
uploadedXML = uploadedXML.replaceAll(filter, "");
System.out.println(uploadedXML);
<someStuff>Bats!</someStuff>

String uploadedXML = "<someStuff>Bats!</someStuff> <name></name>";
String deleteRaise = "<name>";
String closeName = "</name>"
// If an Addenda exists we continue with the process
if (xml_in.contains(deleteRaise)){
uploadedXML.replace(uploadedXML.substring(uploadedXML.indexOf(deleteRaise),uploadedXML.indexOf(closeName)+1),"");
} else {
// Carry on
}enter code here

Parsing XML with StAX with non-unique tag paths, design suggestions

I need to parse a large XML file (probably going to use StAX in Java) and output it into a delimited text file and I have a couple of design questions. First here is an example of the XML
<demographic>
<value>001</value>
<question>Name?</question>
<value>Bob</value>
<question>Last Name?</question>
<value>Smith</value>
<followUpQuestions>
<question>Middle Init.</question>
<value>J</value>
</followUpQuestions>
</demographic>
this would need to be outputted (in the delimited output file) as
001~Bob~Smith~J
so here are my questions:
How can I distinguish between all the different "value" tags, since the tag names are not unique. Currently I tried to resolve this by having 'state' variables that turn on once they pass question-text such as "Name?", however this approach doesnt really work for the first value since I have to check to make sure the 'name' and 'lastName' states are off to ensure I'm getting the first value.
Everytime the client changes the text of the questions (which happens) I have to change the code and recompile it. Is there anyway to avoid this? Maybe save the questions-text in a text file that the program reads in?
Can this be scalable? I need to extract over 100 values and the XML files are usually about 2 gigs large.
Thank you, in advance, for your help (from a Java and XML newbie)!!
UPDATE: here is my attempt to code the solution, can someone please help to streamline? There has to be a less messy way to do this:
import javax.xml.stream.XMLInputFactory;
import javax.xml.stream.XMLStreamConstants;
import javax.xml.stream.XMLStreamException;
import javax.xml.stream.XMLStreamReader;
import java.io.*;
class TestJavaForStackOverflow{
boolean nameState = false,
lastNameState = false,
middleInitState = false;
String name = "",
lastName = "",
middleInit = "",
value = "";
public void parse() throws IOException, XMLStreamException{
XMLInputFactory factory = XMLInputFactory.newInstance();
XMLStreamReader streamReader = factory.createXMLStreamReader(
new FileReader("/n04/data/revmgmt/anthony/scripts/Java_Programs/TestJavaForStackOverflow.xml"));
while(streamReader.hasNext()){
streamReader.next();
if(streamReader.getEventType() == XMLStreamReader.START_ELEMENT){
if("demographic".equals(streamReader.getLocalName())){
parseDemographicInformation(streamReader);
}
}
}
System.out.println(value + "~" + name + "~" + lastName + "~" + middleInit);
}
public void parseDemographicInformation(XMLStreamReader streamReader) throws XMLStreamException {
while(streamReader.hasNext()){
streamReader.next();
if(streamReader.getEventType() == XMLStreamReader.END_ELEMENT){
if("demographic".equals(streamReader.getLocalName())){
return;
}
}
else if(streamReader.getEventType() == XMLStreamReader.START_ELEMENT){
if("question".equals(streamReader.getLocalName())){
streamReader.next();
if("Name?".equals(streamReader.getText())){
nameState = true;
}
else if("Last Name?".equals(streamReader.getText())){
lastNameState = true;
}
else if("Middle Init.".equals(streamReader.getText())){
middleInitState = true;
}
}
else if("value".equals(streamReader.getLocalName())){
streamReader.next();
if(nameState){
name = streamReader.getText();
nameState = false;
}
else if (lastNameState){
lastName = streamReader.getText();
lastNameState = false;
}
else if (middleInitState){
middleInit = streamReader.getText();
middleInitState = false;
}
else {
value = streamReader.getText();
}
}
}
}
}
public static void main(String[] args){
TestJavaForStackOverflow t = new TestJavaForStackOverflow();
try{t.parse();}
catch(IOException e1){}
catch(XMLStreamException e2){}
}
}

I think the flags are not very scalable if you have a lot of different questions to parse, and neither are the global variables to hold the results... if you have 100 questions then you'll need 100 variables, and when they change over time it will be a bear to keep them up to date. I would use a map structure to hold the result, and another one to hold the correspondence between each question text and the corresponding field you are trying to capture (this is not actual Java, just an approximation):
public Map parseDemographicInformation(XmlStream xml, Map questionMap) {
Map record = new Map();
String field = "id";
while((elem = xml.getNextElement())) {
if(elem.tagName == "question") {
field = questionMap[elem.value];
} else if(elem.tagName == "value") {
record[field] = elem.value;
}
}
return record;
}
Then you have something like this to output the result:
String[] fieldsToOutput = { "id", "firstName", "lastName" }; // ideally read this from a file too so it can be changed dynamically
// ...
for(int i=0; i < fieldsToOutput.length; i++){
if(i > 0)
System.out.print("~");
System.out.print(record[fieldsToOutput[i]]);
}
System.out.println();

How to replace words with Parallel arrays

Hello i am new to this forum. I am fairly new to Java. I am trying to convert USA to UK words so that when i input a sentence containing any of the USA words, the output will be will be the sentence but replaced with UK words. This is my attempt:
import javax.swing.JOptionPane;
public class PArraystest
{
public static void main(String [] arg)
{
String[] wordUSA = {"Cell", "Elevator", "Fries", "Gasoline", "Faucet"};
String[] wordUK = {"Mobile", "Lift", "Chips", "Petrol", "Tap"};
String changeUK = "";
String sent;
sent = JOptionPane.showInputDialog("What name do you want to search for?");
for (int i = 0; i < wordUSA.length; i++)
{
if (sent.contains(wordUSA[i]))
{
sent.replace((wordUK)[i],(wordUSA)[i]);
//break;
}
}
//if (changeUK.equals(""))
//System.out.println(" was not found.");
//else
System.out.println(sent);
}
}

Two things:
You need to use assign the string returned from replace to sent again, or sent will be unchanged`.
The replace method is public String replace(char oldChar, char newChar), so the oldChar US word should come first, followed by the UK word.
This is the correct line: sent = sent.replace(wordUSA[i],wordUK[i]);

The replace method returns a new String with the replaced text:
//sent.replace((wordUK)[i],(wordUSA)[i]);
sent = sent.replace((wordUK)[i],(wordUSA)[i]);

Two problems:
First, you should assign the replaced string back to sent.
Second, you should use replaceAll instead of replace.

There's a whole framework of functionality devoted to this in Java called internationalizaion (i18n)
While the sample below is primarily for generation origianlly I thought I'd point it out because you could probably devise how to run it in reverse as well.
Here's a snippet that shows the proper way to go about this:
http://docs.oracle.com/javase/tutorial/i18n/intro/after.html
(all code below is theirs and not my own)
Note that to run this you'll need the resource files from the site or the versions I have provided below from the site
import java.util.*;
public class I18NSample {
static public void main(String[] args) {
String language;
String country;
if (args.length != 2) {
language = new String("en");
country = new String("US");
} else {
language = new String(args[0]);
country = new String(args[1]);
}
Locale currentLocale;
ResourceBundle messages;
currentLocale = new Locale(language, country);
messages = ResourceBundle.getBundle("MessagesBundle", currentLocale);
System.out.println(messages.getString("greetings"));
System.out.println(messages.getString("inquiry"));
System.out.println(messages.getString("farewell"));
}
}
MessagesBundle.properties:
greetings = Hello.
farewell = Goodbye.
inquiry = How are you?
MessagesBundle_en_US.properties:
greetings = Hello.
farewell = Goodbye.
inquiry = How are you?
MessagesBundle_fr_FR.properties:
greetings = Bonjour.
farewell = Au revoir.
inquiry = Comment allez-vous?

How to combine 2 java methods into one efficiently

I'm trying to create a validate java class that receives 4 inputs from an object passed as 1 from the requester. The class needs to convert float inputs to string and evaluate each input to meet a certain format and then throw exceptions complete with error message and code when it fails.
What I have is in two methods and would like to know if there is a better way to combine these two classes into one validate method for the main class to call. I don't seem to be able to get around using the pattern/matcher concept to insure the inputs are formatted correctly. Any help you can give would be very much appreciated.
public class Validator {
private static final String MoneyPattern ="^\\d{1,7}(\\.\\d{1,2})$" ;
private static final String PercentagePattern = "^\\d{1,3}\\.\\d{1,2}$";
private static final String CalendarYearPattern = "^20[1-9][0-9]$";
private int errorcode = 0;
private String errormessage = null;
public Validator(MyInput input){
}
private boolean verifyInput(){
String Percentage = ((Float) input.getPercentage().toString();
String Income = ((Float) input.getIncome().toString();
String PublicPlan = ((Float) input.getPublicPlan().toString();
String Year = ((Float) input.getYear();
try {
if (!doesMatch(Income, MoneyPattern)) {
errormessage = errormessage + "income,";
}
if (!doesMatch(PublicPlan, MoneyPattern)) {
errormessage = errormessage + "insurance plan,";
}
if (!doesMatch(Percentage, PercentagePattern)) {
errormessage = errormessage + "Percentage Plan,";
}
if (!doesMatch(Year, CalendarYearPattern)) {
errormessage = errormessage + "Year,";
}
} catch (Exception e){
errorcode = 111;
errormessage = e.getMessage();
}
}
private boolean doesMatch(String s, String pattern) throws Exception{
try {
Pattern p = Pattern.compile(pattern);
Matcher m = p.matcher(s);
if (!s.equals("")){
if(m.find()){
return true;
} else {
return false;
}
}else {
return false;
}
} catch (PatternSyntaxException pse){
errorcode = 111;
errormessage = pse.getMessage();
}
}
}

This code is borked from the word "go". You have a constructor into which you pass a MyInput reference, but there's no code in the ctor and no private data member to receive it. It looks like you expect to use input in your doesMatch() method, but it's a NullPointerException waiting to happen.
Your code doesn't follow the Sun Java coding standards; variable names should be lower case.
Why you wouldn't do that input validation in the ctor, when you actually receive the value, is beyond me. Perhaps you really meant to pass it into that verifyInput() method.
I would worry about correctness and readability before concerning myself with efficiency.
I'd have methods like this:
public boolean isValidMoney(String money) { // put the regex here }
public boolean isValidYear(String year) { // the regex here }
I think I'd prefer a real Money class to a String. There's no abstraction whatsoever.
Here's one bit of honesty:
private static final String CalendarYearPattern = "^20[1-9][0-9]$";
I guess you either don't think this code will still be running in the 22nd century or you won't be here to maintain it.

One way of doing this would be with DynamicBeans.
package com.acme.validator;
import java.util.HashMap;
import java.util.Map;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import org.apache.commons.beanutils.PropertyUtils;
public class Validator {
//A simple optimisation of the pattern
private static final Pattern MoneyPattern = Pattern.compile("^\\d{1,7}(\\.\\d{1,2})$");
private static final Pattern PercentagePattern = Pattern.compile("^\\d{1,3}\\.\\d{1,2}$");
private static final Pattern CalendarYearPattern = Pattern.compile("^20[1-9][0-9]$");
public String Validator(MyInput input) {
String errormessage = "";
/*
* Setting these up as Maps.
* Ideally this would be a 'simple bean'
* but that goes beyond the scope of the
* original question
*/
Map<String,Pattern> patternMap = new HashMap<String,Pattern>();
patternMap.put("percentage", PercentagePattern);
patternMap.put("publicPlan", MoneyPattern);
patternMap.put("income", MoneyPattern);
patternMap.put("year", CalendarYearPattern);
Map<String,String> errorMap = new HashMap<String,String>();
errorMap.put("percentage", "Percentage Plan,");
errorMap.put("publicPlan", "insurance plan,");
errorMap.put("income", "income,");
errorMap.put("year", "Year,");
for (String key : patternMap.keySet()) {
try {
String match = ((Float) PropertyUtils.getSimpleProperty(input, key)).toString();
Matcher m = patternMap.get(key).matcher(match);
if ("".equals(match) || !m.find()) {
errormessage = errormessage + errorMap.get(key);
}
} catch (Exception e) {
errormessage = e.getMessage(); //since getMessage() could be null, you need to work out some way of handling this in the response
//don't know the point of the error code so remove this altogether
break; //Assume an exception trumps any validation failure
}
}
return errormessage;
}
}
I've made a few assumptions about the validation rules (for simplicity used 2 maps but you could also use a single map and a bean containing both the Pattern and the Message and even the 'error code' if that is important).
The key 'flaw' in your original setup and what would hamper the solution above, is that you are using 'year' as Float in the input bean.
(new Float(2012)).toString()
The above returns "2012.0". This will always fail your pattern. When you start messing about with the different types of objects potentially in the input bean, you may need to consider ensuring they are String at the time of creating the input bean and not, as is the case here, when they are retrieved.
Good Luck with the rest of your Java experience.