I want to write a json file in java, but it doesn't work, I get this warning:
I want to know how to do this, because I am going to convert a cfg file that is tabbed to json.
Type safety: The method add(Object) belongs to the raw type ArrayList. References to generic type ArrayList<E> should be parameterized
and I have this code:
package json;
import java.io.File;
import java.io.FileWriter;
import java.io.IOException;
import org.json.simple.JSONArray;
import org.json.simple.JSONObject;
public class JsonWriter {
public static void main(String[] args) {
JSONObject countryObj = new JSONObject();
countryObj.put("Name", "India");
countryObj.put("Population", new Integer(1000000));
JSONArray listOfStates = new JSONArray();
listOfStates.add("Madhya Pradesh");
listOfStates.add("Maharastra");
listOfStates.add("Rajasthan");
countryObj.put("States", listOfStates);
try {
// Writing to a file
File file=new File("JsonFile.json");
file.createNewFile();
FileWriter fileWriter = new FileWriter(file);
System.out.println("Writing JSON object to file");
System.out.println("-----------------------");
System.out.print(countryObj);
fileWriter.write(countryObj.toJSONString());
fileWriter.flush();
fileWriter.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
I would suggest that you just make a simple ArrayList with your objects, and then serialize them into JSON with a serializer (Using the Jacksoin library in the example below). It would look something like this:
First, define your model in a class (Made without incapsulations for readability):
public class Country{
public String name;
public Integer population;
public List<String> states;
}
Then you can go ahead and create it, and populate the list:
import java.io.File;
import java.io.IOException;
import org.codehaus.jackson.JsonGenerationException;
import org.codehaus.jackson.map.JsonMappingException;
import org.codehaus.jackson.map.ObjectMapper;
public class JsonWriter {
public static void main(String[] args) {
Country countryObj = new Country();
countryObj.name = "India";
countryObj.population = 1000000;
List<String> listOfStates = new ArrayList<String>();
listOfStates.add("Madhya Pradesh");
listOfStates.add("Maharastra");
listOfStates.add("Rajasthan");
countryObj.states = listOfStates ;
ObjectMapper mapper = new ObjectMapper();
try {
// Writing to a file
mapper.writeValue(new File("c:\\country.json"), countryObj );
} catch (IOException e) {
e.printStackTrace();
}
}
}
Related
I'm trying a simple test where the code appends a few json entries, however it is getting overwritten each time (the json file will only have 1 entry in it after running). I know I need to somehow create an array in JSON using '[]', but how would I go about doing that? Also, is there a better way to be doing this? I've been searching around and every library seems clunky with lots of user written code. Thanks
public class REEEE {
private static Staff createStaff() {
Staff staff = new Staff();
staff.setName("mkyong");
staff.setAge(38);
staff.setPosition(new String[] { "Founder", "CTO", "Writer" });
Map<String, Double> salary = new HashMap() {
{
put("2010", 10000.69);
}
};
staff.setSalary(salary);
staff.setSkills(Arrays.asList("java", "python", "node", "kotlin"));
return staff;
}
public static void main(String[] args) throws IOException {
ObjectMapper mapper = new ObjectMapper();
File file = new File("src//j.json");
for(int i = 0; i < 4; i++) {
Staff staff = createStaff();
try {
// Java objects to JSON file
mapper.writeValue(file, staff);
// Java objects to JSON string - compact-print
String jsonString = mapper.writeValueAsString(staff);
} catch (IOException e) {
e.printStackTrace();
}
}
}
}
You can add staff in List and then write the list to file as below,
List<Staff> staffList = new LinkedList<>()
for(int i = 0; i < 4; i++) {
Staff staff = createStaff();
staffList.add(staff);
}
mapper.writeValue(file, staffList);
Hope it helps.
Jackson was implemented to parse and generate JSON payloads. All extra logic related with adding new element to array and writing back to file you need to implement yourself. It should not be hard to do:
class JsonFileAppender {
private final ObjectMapper jsonMapper;
public JsonFileAppender() {
this.jsonMapper = JsonMapper.builder().build();
}
public void appendToArray(File jsonFile, Object value) throws IOException {
Objects.requireNonNull(jsonFile);
Objects.requireNonNull(value);
if (jsonFile.isDirectory()) {
throw new IllegalArgumentException("File can not be a directory!");
}
JsonNode node = readArrayOrCreateNew(jsonFile);
if (node.isArray()) {
ArrayNode array = (ArrayNode) node;
array.addPOJO(value);
} else {
ArrayNode rootArray = jsonMapper.createArrayNode();
rootArray.add(node);
rootArray.addPOJO(value);
node = rootArray;
}
jsonMapper.writeValue(jsonFile, node);
}
private JsonNode readArrayOrCreateNew(File jsonFile) throws IOException {
if (jsonFile.exists() && jsonFile.length() > 0) {
return jsonMapper.readTree(jsonFile);
}
return jsonMapper.createArrayNode();
}
}
Example usage with some usecases:
import com.fasterxml.jackson.databind.JsonNode;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.json.JsonMapper;
import com.fasterxml.jackson.databind.node.ArrayNode;
import java.io.File;
import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.util.Arrays;
import java.util.Collections;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Objects;
public class JsonPathApp {
public static void main(String[] args) throws Exception {
Path jsonTmpFile = Files.createTempFile("json", "array");
JsonFileAppender jfa = new JsonFileAppender();
// Add POJO
jfa.appendToArray(jsonTmpFile.toFile(), createStaff());
printContent(jsonTmpFile); //1
// Add primitive
jfa.appendToArray(jsonTmpFile.toFile(), "Jackson");
printContent(jsonTmpFile); //2
// Add another array
jfa.appendToArray(jsonTmpFile.toFile(), Arrays.asList("Version: ", 2, 10, 0));
printContent(jsonTmpFile); //3
// Add another object
jfa.appendToArray(jsonTmpFile.toFile(), Collections.singletonMap("simple", "object"));
printContent(jsonTmpFile); //4
}
private static Staff createStaff() {
Staff staff = new Staff();
staff.setName("mkyong");
staff.setAge(38);
staff.setPosition(new String[]{"Founder", "CTO", "Writer"});
Map<String, Double> salary = new HashMap<>();
salary.put("2010", 10000.69);
staff.setSalary(salary);
staff.setSkills(Arrays.asList("java", "python", "node", "kotlin"));
return staff;
}
private static void printContent(Path path) throws IOException {
List<String> lines = Files.readAllLines(path);
System.out.println(String.join("", lines));
}
}
Above code prints 4 lines:
1
[{"name":"mkyong","age":38,"position":["Founder","CTO","Writer"],"salary":{"2010":10000.69},"skills":["java","python","node","kotlin"]}]
2
[{"name":"mkyong","age":38,"position":["Founder","CTO","Writer"],"salary":{"2010":10000.69},"skills":["java","python","node","kotlin"]},"Jackson"]
3
[{"name":"mkyong","age":38,"position":["Founder","CTO","Writer"],"salary":{"2010":10000.69},"skills":["java","python","node","kotlin"]},"Jackson",["Version: ",2,10,0]]
4
[{"name":"mkyong","age":38,"position":["Founder","CTO","Writer"],"salary":{"2010":10000.69},"skills":["java","python","node","kotlin"]},"Jackson",["Version: ",2,10,0],{"simple":"object"}]
Objective : I want to read a WSDL and print the services in the WSDL, complex types and Complex type definitions.
Worked : I've used WSDL4J for reading WSDL and successfully able to print the services and their parameters (complex types). Now I want to read the complex type definitions which is available in XSD. I'm unable to read XSD .Is ther any way to do it ?
I'm getting XSModel as null
import java.util.ArrayList;
import java.util.Collection;
import java.util.List;
import java.util.Map;
import javax.wsdl.BindingOperation;
import javax.wsdl.Definition;
import javax.wsdl.WSDLException;
import javax.wsdl.xml.WSDLReader;
import org.w3c.dom.bootstrap.DOMImplementationRegistry;
import com.ibm.wsdl.BindingImpl;
import com.ibm.wsdl.xml.WSDLReaderImpl;
import com.sun.org.apache.xerces.internal.impl.xs.XSImplementationImpl;
import com.sun.org.apache.xerces.internal.xs.XSLoader;
import com.sun.org.apache.xerces.internal.xs.XSModel;
public class WSDLDetails {
public static void main(String[] args) {
try {
String wsdlURL = "https://abc.xyz.com/webservice/MessagingSevice?WSDL";
String xsdURL = "https://abc.xyz.com/webservice/MessagingSevice?xsd=1";
java.lang.System.setProperty("https.protocols", "TLSv1.2");
getAllBindingOperation(wsdlURL);
readXSD(xsdURL);
} catch (Exception e) {
e.printStackTrace();
}
}
public static List<String> getAllBindingOperation(String wsdlUrl) {
List<BindingOperation> operationList = new ArrayList();
List<String> nameList = new ArrayList();
try {
WSDLReader reader = new WSDLReaderImpl();
reader.setFeature("javax.wsdl.verbose", false);
Definition definition = reader.readWSDL(wsdlUrl.toString());
Map<String, BindingImpl> defMap = definition.getAllBindings();
Collection<BindingImpl> collection = defMap.values();
for (BindingImpl binding : collection) {
operationList.addAll(binding.getBindingOperations());
}
for (BindingOperation operation:operationList) {
nameList.add(operation.getName());
System.out.println("Name :: " + operation.getName());
System.out.println("Request :: " + operation.getBindingInput());
System.out.println("Response :: " + operation.getBindingOutput());
}
} catch (WSDLException e) {
System.out.println("get wsdl operation fail.");
e.printStackTrace();
}
return nameList;
}
public static void readXSD(String xsdURL) {
try {
System.setProperty(DOMImplementationRegistry.PROPERTY, "com.sun.org.apache.xerces.internal.dom.DOMXSImplementationSourceImpl");
DOMImplementationRegistry registry = DOMImplementationRegistry.newInstance();
com.sun.org.apache.xerces.internal.impl.xs.XSImplementationImpl impl = (XSImplementationImpl) registry.getDOMImplementation("XS-Loader");
XSLoader schemaLoader = impl.createXSLoader(null);
XSModel model = schemaLoader.loadURI(xsdURL);
System.out.println(model);
} catch (Exception e) {
e.printStackTrace();
}
}
You can use xsd2java plugin with maven
https://github.com/qaware/xsd2java-gradle-plugin
Here is an example showing how to retrieve the XSModel from an XSD URL, and print the complex types declared therein.
import org.apache.xerces.impl.xs.XMLSchemaLoader;
import org.apache.xerces.impl.xs.XSComplexTypeDecl;
import org.apache.xerces.impl.xs.XSElementDecl;
import org.apache.xerces.xs.XSConstants;
import org.apache.xerces.xs.XSModel;
import org.apache.xerces.xs.XSNamedMap;
import org.apache.xerces.xs.XSTypeDefinition;
public class Test {
public static void main(String[] args) {
try {
String xsdURL = "http://fsharp.github.io/FSharp.Data/data/po.xsd";
XMLSchemaLoader xsLoader = new XMLSchemaLoader();
XSModel xsModel = xsLoader.loadURI(xsdURL);
// print global element declarations
System.out.println("\nGlobal Element Declarations:");
XSNamedMap globalElemDecls = xsModel.getComponents(XSConstants.ELEMENT_DECLARATION);
globalElemDecls.forEach((k,v) -> System.out.println((XSElementDecl) v));
// print global complex type declarations
System.out.println("\nGlobal Complex Type Declarations:");
XSNamedMap globalComplexTypeDecls = xsModel.getComponents(XSTypeDefinition.COMPLEX_TYPE);
globalComplexTypeDecls.forEach((k,v) -> System.out.println((XSComplexTypeDecl) v));
} catch (Exception e) {
e.printStackTrace();
}
}
}
If you got null at xsLoader.loadURI(xsdURL), it is likely there are some flaws in the given XSD file. For example, "White spaces are required between publicId and systemId". You might need to fix these flaws first.
I have a problem with huge JSON file (1GB) which contains an array of JSON objects but all of them are in one line. So it looks like...
[{JsonObject1},{JsonObject1},{JsonObject1},...,{JsonObject999999}]
I'm not able to save the content into the memory so I wanted to do this using streaming. I know how to stream line by line but if I have everything in one line only how can I stream JSON object one after another from this one line array?
I tried to browse the internet but I couldn't find anything :(
Using google gson, you can whip up something that operates lazily:
Maintained as a Gist here:
<script src="https://gist.github.com/smac89/bdcb9b08fcdf9d055150824d57ab3513.js"></script>
import com.google.gson.Gson;
import com.google.gson.stream.JsonReader;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.lang.reflect.Type;
import java.net.URL;
import java.util.Iterator;
import java.util.Spliterators;
import java.util.stream.Stream;
import java.util.stream.StreamSupport;
public class ReadJsonFile {
private static final class JsonIterator<T> implements Iterator<T> {
private final Gson gson;
private final Type objectType;
private final JsonReader reader;
private JsonIterator(JsonReader reader, Gson gson, Type objectType) {
this.gson = gson;
this.objectType = objectType;
this.reader = reader;
}
#Override
public boolean hasNext() {
try {
return reader.hasNext();
} catch (IOException ioe) {
return false;
}
}
#Override
public T next() {
return gson.fromJson(reader, objectType);
}
}
public static <J> Stream<J> readJsonFromFile(Gson gson, URL jsonFile, Type type) throws IOException {
JsonReader reader = new JsonReader(
new BufferedReader(new InputStreamReader(jsonFile.openStream())));
reader.beginArray();
if (!reader.hasNext()) {
return Stream.empty();
}
return StreamSupport.stream(Spliterators.spliteratorUnknownSize(
new JsonIterator<J>(reader, gson, type), 0), false).onClose(() -> {
try {
reader.close();
} catch (IOException ioe) {
}
});
}
}
data.json
<script src="https://gist.github.com/smac89/15fc3bffa4f965d18587eec2db4972dd.js"></script>
I am trying to parse a json file with JSONParse and am getting this error, with the error occurring in beginning of the following json:
Unexpected token COLON(:) at position 11.
{"276716878": {
"followers": [
2435018580,
1664252310,
372262434
],
"following": [
16211434,
945440959,
130682467,
264257750,
900526363,
318231688,
40335029,
64044676
]
}}
I also wrote the json file with the following:
FileWriter out = new FileWriter(JSON_FILE);
out.write(json.toString(1));
out.flush();
out.close();
There could be some format error in the json string you passed. Validate your json string. The below sample code works fine.
import java.io.FileWriter;
import java.io.IOException;
import java.util.logging.Level;
import java.util.logging.Logger;
import org.json.JSONException;
import org.json.JSONObject;
public class Test {
private static final Logger logger = Logger.getLogger(Test.class.getName());
private static final String JSON_FILE = "/home/visruth/Desktop/Visruth.txt";
public static void main(String[] args) {
String jsonText = "{\"215876567\": { \"followers\": [ 2464054938, 772677937]}}";
try (
FileWriter out = new FileWriter(JSON_FILE);
) {
JSONObject json = new JSONObject(jsonText);
int indentFactor = 1;
String prettyprintedJSON = json.toString(indentFactor);
System.out.println(prettyprintedJSON);
out.write(prettyprintedJSON);
} catch (JSONException e) {
logger.log(Level.SEVERE, e.getMessage());
} catch (IOException e) {
logger.severe(e.getMessage());
}
}
}
Assign your json text in jsonText variable and try.
I think you are referring classes from different apis for this purpose. Just use only one api.
Here is a demo code which works fine with the given json string in the question.
import java.io.FileWriter;
import org.json.simple.JSONArray;
import org.json.simple.JSONObject;
import org.json.simple.parser.JSONParser;
import org.json.simple.parser.ParseException;
import org.junit.Assert;
import org.junit.Test;
public class TestCase {
private static final String JSON_FILE = "/home/visruth/Desktop/Visruth.txt";
#Test
public void testJSONParser() throws Exception {
JSONParser parser = new JSONParser();
try (
FileWriter out = new FileWriter(JSON_FILE);
) {
String jsonText = "{\"276716878\": { \"followers\": [ 2435018580, 1664252310, 372262434 ], \"following\": [ 16211434, 945440959, 130682467, 264257750, 900526363, 318231688, 40335029, 64044676 ] }}";
Object obj = parser.parse(jsonText);
JSONObject jsonObject = (JSONObject) obj;
JSONObject jsonObject215876567 = (JSONObject)jsonObject.get("276716878");
JSONArray followers = (JSONArray)(jsonObject215876567.get("followers"));
Assert.assertEquals("[2435018580,1664252310,372262434]", followers.toString());
String jsonStringFromJsonObject = jsonObject.toString();// There is no argument as an int
out.write(jsonStringFromJsonObject);
} catch (ParseException e) {
Assert.fail(e.getMessage());
}
}
}
I am trying to take the contents of an ArrayList and put them into an XML file. Does anyone have a quick,clean and easy solution to this rather that having to use streams and handle exceptions?
For more information, Here is the code I have currently I am getting problem with it, one of which its not creating the file.
package ie.wit.io;
import ie.wit.abs.Device;
import ie.wit.abs.Device;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.Serializable;
import java.util.ArrayList;
import java.util.List;
import javax.swing.JOptionPane;
public class FileHandler
{
private FileOutputStream outByteStream;
private ObjectOutputStream OOStream;
private FileInputStream inByteStream;
private ObjectInputStream OIStream;
private File aFile;
public void setUpFile()
{
aFile = new File("data.xml");
}
public boolean isFileEmpty()
{
return (aFile.length() <= 0);
}
public void writeToFile(ArrayList<Device> team)
{
try
{
outByteStream = new FileOutputStream(aFile);
OOStream = new ObjectOutputStream(outByteStream);
OOStream.writeObject(team);
outByteStream.close();
OOStream.close();
}
catch(IOException e)
{
JOptionPane.showMessageDialog(null,"I/O Error" + e + "\nPlease Contact your Administrator :-)");
}
}
currentClass)
public ArrayList<Device> readFromFile()
{
ArrayList<Device> temp = null;
try
{
inByteStream = new FileInputStream(aFile);
OIStream = new ObjectInputStream(inByteStream);
if(!this.isFileEmpty())
temp = (ArrayList<Device>)OIStream.readObject();
inByteStream.close();
OIStream.close();
}
catch(IOException e)
{
JOptionPane.showMessageDialog(null,"I/O Error" + e + "\nPlease Contact your Administrator :-)");
}
catch(Exception e)
{
JOptionPane.showMessageDialog(null,"General Error" + e + "\nPlease Contact your Administrator :-)");
}
return temp;
}
}
There are many libraries to do that task.
Here is what I'm doing so far. Edit as per your requirement.
protected String getDocmentsAsString(List<News> documentsListByIndex) {
if(documentsListByIndex.size()>0){
try {
XStream xstream = new XStream(new JsonHierarchicalStreamDriver());
xstream.setMode(XStream.NO_REFERENCES);
xstream.alias("news", News.class);
return xstream.toXML(documentsListByIndex);
} catch (Exception e) {
e.printStackTrace();
}
}
return null;
}
Im using http://x-stream.github.io/json-tutorial.html
You can use a StringBuilder and generate the XML yourself.. It depends on how many items you want to convert. The fastest way is just pushing out the XML data using a StringBuilder.
I recommend to:
create a XSD
generate JAXB Java classes (e.g. using a Maven Plugin)
create instances of the JAXB Java classes and fill up the data
marshal the JAXB Java classes to XML