We Keep Coding

How to return 2 values from one method and use both values in one class?

I'm trying out this code from Microsoft, however I wanted to combine the 2 features they made. One is analyzing image and one is detecting celebrities. However, I'm having a hard time on how will I return 2 values from one function.
Here is the process method...
private String process() throws VisionServiceException, IOException {
Gson gson = new Gson();
String model = "celebrities";
ByteArrayOutputStream output = new ByteArrayOutputStream();
bitmapPicture.compress(Bitmap.CompressFormat.JPEG, 100, output);
ByteArrayInputStream inputStream = new ByteArrayInputStream(output.toByteArray());
AnalysisResult v = this.client.describe(inputStream, 1);
AnalysisInDomainResult m = this.client.analyzeImageInDomain(inputStream,model);
String result = gson.toJson(v);
String result2 = gson.toJson(m);
Log.d("result", result);
return result, result2;
}
And combine the 2 results with this method...
#Override
protected void onPostExecute(String data) {
super.onPostExecute(data);
mEditText.setText("");
if (e != null) {
mEditText.setText("Error: " + e.getMessage());
this.e = null;
} else {
Gson gson = new Gson();
AnalysisResult result = gson.fromJson(data, AnalysisResult.class);
//pang detect ng peymus...
AnalysisInDomainResult result2 = gson.fromJson(data, AnalysisInDomainResult.class);
//decode the returned result
JsonArray detectedCelebs = result2.result.get("celebrities").getAsJsonArray();
if(result2.result != null){
mEditText.append("Celebrities detected: "+detectedCelebs.size()+"\n");
for(JsonElement celebElement: detectedCelebs) {
JsonObject celeb = celebElement.getAsJsonObject();
mEditText.append("Name: "+celeb.get("name").getAsString() +", score" +
celeb.get("confidence").getAsString() +"\n");
}
}else {
for (Caption caption: result.description.captions) {
mEditText.append("Your seeing " + caption.text + ", confidence: " + caption.confidence + "\n");
}
mEditText.append("\n");
}
/* for (String tag: result.description.tags) {
mEditText.append("Tag: " + tag + "\n");
}
mEditText.append("\n");
mEditText.append("\n--- Raw Data ---\n\n");
mEditText.append(data);*/
mEditText.setSelection(0);
}
}
Thanks in advance!

you can use. the parameter are two objects so can you can put everything
final Pair<String, String> pair = Pair.create("1", "2");
String a = pair.first;
String b = pair.second;

Simply use Bundle
Bundle bundle = new Bundle();
bundle.putString("key_one", "your_first_value");
bundle.putString("key_two", "your_second_value");
return bundle;
You can add multiple values with different types in Bundle.In this case your method's return type should be Bundle.

or AbstractMap#SimpleEntry (or as of Java-9 Map#entry)
You can always return two values via Arrays.asList(one, two) also

How to get an Enum value from a Multimap

Here is my enum:
public enum StaffRanks {
HELPER("helpers"),
MODERATOR("moderators"),
ADMINISTRATOR("administrators"),
DEVELOPER("developers"),
OWNER("owners");
private String name;
StaffRanks(String name) {
this.setName(name);
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
}
This is how I create my Multimap:
public static Multimap<String, StaffRanks> staffMembers;
public static void fetchPlayerRanks() {
JsonParser parser = new JsonParser();
try {
Object obj = parser.parse(new FileReader(".\\Data\\staff_list.json"));
JsonObject staffList = (JsonObject) obj;
Type listType = new TypeToken<List<String>>() {
}.getType();
staffMembers = ArrayListMultimap.create();
for (StaffRanks rank : StaffRanks.values()) {
staffMembers.put(new Gson().fromJson(staffList.get(rank.getName()), listType), rank);
}
} catch (Exception e) {
e.printStackTrace();
}
}
And this is how I want to use it:
int index = 39550;
for (String player : allStaffNames) {
onlineStatus = "#red#Offline";
if (onlineStaff.contains(PlayerHandler.getPlayer(player))) {
onlineStatus = "#gre#Online";
}
if (staffMembers.containsKey(player)) {
playerClient.getPA().sendFrame126("[" + staffMembers.get(player).getName() + "]#cya#" + Misc.formatPlayerName(player) + ": ", index);
}
playerClient.getPA().sendFrame126(onlineStatus, index - 1);
index += 2;
}
Now, the question is: how I can get the name from the enum inside the Multimap?
Here is what I tried. But, it didn't work.
staffMembers.get(player).getName()
Here is what the Staff_list.json file looks like:
{
"owners":['chuck'],
"developers":['tyrant','stan'],
"serverManagers":['logical'],
"staffManagers":['bench press', 'bench press2'],
"communityManagers":['cleave'],
"administrators":['zeven', 'reavers', 'redaeran', 'stuart'],
"moderators":['searwen', 'potentials', 'maud', 'lickylicky'],
"helpers":['megafun12', 'rhysj', 'vaping', 'punch']
}

Because staffMembers is defined as Multimap<String, StaffRanks>, it means that you should read this as Map<String, Collection<StaffRanks>> with shiny Guava interface for such case (i.e. mapping key to a collection of values). So in your case what you're actually trying to do is:
Collection<StaffRanks> staffRanksForPlayer = staffMembers.get(player);
staffRanksForPlayer.getName(); // BOOM!
If you read / attached an error message, it would be much easier. Anyway, you have two options here:
You're using wrong collection type because you want Map<String, StaffRank> if one player can have only one rank - if so, change collection to Map and you're good.
You have to find a matching rank somehow or use all of them in your code. For example, the latter could be achieved with Java 8:
List<String> staffRanksNamesForPlayer = staffMembers.get(player).stream()
.map(StaffRanks::getName)
.collect(Collectors.toList());
// use list's `toString()` in your code to print its contents
playerClient.getPA().sendFrame126("[" + staffRanksNamesForPlayer.toString()
+ "]#cya#" + Misc.formatPlayerName(player) + ": ", index);
One more thing: generally you want to specify which specific Multimap interface you're using: ListMultimap or SetMultimap.

How do I get a list of all JSON paths to values from a JSON String?

My goal is to read a JSON file and understand the location of all the values, so that when I encounter that same JSON, I can easily read all the values. I am looking for a way to return a list containing all of the paths to each data value, in Jayway JsonPath format.
Example JSON:
{
"shopper": {
"Id": "4973860941232342",
"Context": {
"CollapseOrderItems": false,
"IsTest": false
}
},
"SelfIdentifiersData": {
"SelfIdentifierData": [
{
"SelfIdentifierType": {
"SelfIdentifierType": "111"
}
},
{
"SelfIdentifierType": {
"SelfIdentifierType": "2222"
}
}
]
}
}
Ideally I would like to take that JSON as a String and do something like this:
String json = "{'shopper': {'Id': '4973860941232342', 'Context': {'CollapseOrderItems': false, 'IsTest': false } }, 'SelfIdentifiersData': {'SelfIdentifierData': [{'SelfIdentifierType': {'SelfIdentifierType': '111'} }, {'SelfIdentifierType': {'SelfIdentifierType': '2222'} } ] } }";
Configuration conf = Configuration.defaultConfiguration();
List<String> jsonPaths = JsonPath.using(conf).parse(json).read("$");
for (String path : jsonPaths) {
System.out.println(path);
}
This code would print this, which is the location of all values in the JSON:
$.shopper.Id
$.shopper.Context.CollapseOrderItems
$.shopper.Context.IsTest
$.SelfIdentifiersData[0].SelfIdentifierData.SelfIdentifierType.SelfIdentifierType
$.SelfIdentifiersData[1].SelfIdentifierData.SelfIdentifierType.SelfIdentifierType
Then ideally, I would be able to take that list and parse the same JSON object to get each value present.
//after list is created
Object document = Configuration.defaultConfiguration().jsonProvider().parse(json);
for (String path : jsonPaths) {
Object value = JsonPath.read(document, path);
//do something
}
I am aware that I could get a Map that is a representation of the JSON file, but I am not sure that provides the same ease of access to retrieve all the values. If there is a easy way to do with JSONPath, that would be great, otherwise any other approaches are welcome.

I came up with a solution, sharing in case anyone else is looking for the same thing:
public class JsonParser {
private List<String> pathList;
private String json;
public JsonParser(String json) {
this.json = json;
this.pathList = new ArrayList<String>();
setJsonPaths(json);
}
public List<String> getPathList() {
return this.pathList;
}
private void setJsonPaths(String json) {
this.pathList = new ArrayList<String>();
JSONObject object = new JSONObject(json);
String jsonPath = "$";
if(json != JSONObject.NULL) {
readObject(object, jsonPath);
}
}
private void readObject(JSONObject object, String jsonPath) {
Iterator<String> keysItr = object.keys();
String parentPath = jsonPath;
while(keysItr.hasNext()) {
String key = keysItr.next();
Object value = object.get(key);
jsonPath = parentPath + "." + key;
if(value instanceof JSONArray) {
readArray((JSONArray) value, jsonPath);
}
else if(value instanceof JSONObject) {
readObject((JSONObject) value, jsonPath);
} else { // is a value
this.pathList.add(jsonPath);
}
}
}
private void readArray(JSONArray array, String jsonPath) {
String parentPath = jsonPath;
for(int i = 0; i < array.length(); i++) {
Object value = array.get(i);
jsonPath = parentPath + "[" + i + "]";
if(value instanceof JSONArray) {
readArray((JSONArray) value, jsonPath);
} else if(value instanceof JSONObject) {
readObject((JSONObject) value, jsonPath);
} else { // is a value
this.pathList.add(jsonPath);
}
}
}
}

Refer to this utility : https://github.com/wnameless/json-flattener
Perfect answer to your requirement. Provides Flattened map and Flattened strings for complex json strings.
I am not the author of this but have used it successfully for my usecase.

Jackson read value as string

I have an object with unknown values, say
{
"data": [
{"a":...,
"dont_know_what_else_is_here":....}
]
}
And I just want to store the value of "data" as a string into a variable/database.
How should I read it from the streaming API?

Provided that you have already read this object into JsonNode, you can do it like this:
String content = jsonNode.get("data").textValue();
UPD: since you're using a streaming parser, this example on Jackson usage might help.
UPD: the method name is now textValue() - docs

When we try to fetch data in form of string from JsonNode,we usually use asText, but we should use textValue instead.
asText: Method that will return a valid String representation of the container value, if the node is a value node (method isValueNode() returns true), otherwise empty String.
textValue: Method to use for accessing String values. Does NOT do any conversions for non-String value nodes; for non-String values (ones for which isTextual() returns false) null will be returned. For String values, null is never returned (but empty Strings may be)
So Let's take an example,
JsonNode getJsonData(){
ObjectMapper mapper = new ObjectMapper();
ObjectNode node = mapper.createObjectNode();
node.put("anyParameter",null);
return node;
}
JsonNode node = getJsonData();
json.get("anyParameter").asText() // this will give output as "null"
json.get("").textValue() // this will give output as null

You can get the data in a map according to key value pairs.
Map<String, Object> mp = mapper.readValue(new File("xyz.txt"),new TypeReference<Map<String, Object>>() {});
Now get the value from map:
mp.get("data");

Assuming you've got a parser already and it points to "data" token (e.g. from custom deserializer) you can do the following:
ObjectMapper mapper = new ObjectMapper();
JsonNode treeNode = mapper.readTree(parser);
return treeNode.toString();
This will get you String containing the value of the "data".

You can have some Entity class for JSON result.
String json = "your_json";
ObjectMapper mapper = new ObjectMapper();
Entity entity = mapper .readValue(json, Entity.class);
// here you can do everything with entity as you wish
// to write Entity value as String when you wish
String text = mapper.writeValueAsString(object);
// to write Entity child's value as String when you wish (let's data contain data part)
String data = mapper.writeValueAsString(object.getData());

Let's say you have a POJO java class called User(Taken from this)
public class User {
public enum Gender { MALE, FEMALE };
public class Name {
private String _first, _last;
public String getFirst() { return _first; }
public String getLast() { return _last; }
public void setFirst(String s) { _first = s; }
public void setLast(String s) { _last = s; }
}
private Gender _gender;
private Name _name;
private boolean _isVerified;
private byte[] _userImage;
public Name getName() { return _name; }
public boolean isVerified() { return _isVerified; }
public Gender getGender() { return _gender; }
public byte[] getUserImage() { return _userImage; }
public void setName(Name n) { _name = n; }
public void setVerified(boolean b) { _isVerified = b; }
public void setGender(Gender g) { _gender = g; }
public void setUserImage(byte[] b) { _userImage = b; }
}
So now you have JSON string which is coming from any place somewhere like web socket or somewhere else.As an example assume this is the string you are getting
String json = "{\n" +
" \"name\" : { \"first\" : \"Joe\", \"last\" : \"Sixpack\" },\n" +
" \"gender\" : \"MALE\",\n" +
" \"verified\" : false,\n" +
" \"userImage\" : \"Rm9vYmFyIQ==\"\n" +
"}";
Now you can convert this JSON string into POJO object just using this piece of code.
ObjectMapper mapper = new ObjectMapper();
User user = mapper .readValue(json, User.class);

I assume you just want to read a sub-tree from input using Streaming API -- but in the end, you need to whole sub-tree as one thing to store in DB (or variable).
So what you probably want to use is JsonParser.readValueAs(MyType.class) -- this will call ObjectMapper (and for it to work, parser has to be created via JsonFactory accessed from ObjectMapper; or you need to call JsonFactory.setCodec(mapper)).
If content is arbitrary, you can read it as Map or JsonNode:
Map<String,Object> map = parser.readValueAs(Map.class);
// or
JsonNode root = parser.readValueAsTree();
as soon as JsonParser is pointing to START_ELEMENT of the JSON Object you want to databind.

If using String data in createParser(data), i use this method to collect string content with streaming api:
if ("data".equals(fieldname))
String strData = getValueAsString(jp);
and
private static String getValueAsString(JsonParser jp)
throws com.fasterxml.jackson.core.JsonParseException, IOException {
JsonToken token = jp.getCurrentToken();
int counter = 0;
long startIndex = jp.getCurrentLocation().getCharOffset();
long endIndex = 0;
if (token == JsonToken.START_OBJECT) {
// JsonLocation location = jp.getCurrentLocation();
// startIndex = location.getCharOffset();
// System.out.println("，location=" + new Gson().toJson(location) +
// ", start=" + startIndex);
counter++;
while (counter > 0) {
token = jp.nextToken();
if (token == JsonToken.START_OBJECT)
counter++;
if (token == JsonToken.END_OBJECT) {
counter--;
endIndex = jp.getCurrentLocation().getCharOffset();
}
}
return data.substring((int) startIndex - 1, (int) endIndex);
} else if (token == JsonToken.START_ARRAY) {
counter++;
while (counter > 0) {
token = jp.nextToken();
if (token == JsonToken.START_ARRAY)
counter++;
if (token == JsonToken.END_ARRAY) {
counter--;
endIndex = jp.getCurrentLocation().getCharOffset();
}
}
return data.substring((int) startIndex - 1, (int) endIndex);
} else {
return jp.getText();
}
}
it works when data source is String. for none string source such as file, using JsonLocation.getByteOffset() instead of JsonLocation.getCharOffset()

Finally figured out the solution from reading the tutorial page.
Just to give others a pointer here:
Switch to using a MappingJSONFactory when creating the parser:
HttpResponse response = client.execute(request);
JsonFactory jfactory = new MappingJsonFactory();
JsonParser parser=jfactory.createJsonParser(response.getEntity().getContent());
Then you can just do
parser.readValueAsTree().toString();
or parse it however you want.

Java toString() using reflection?

I was writing a toString() for a class in Java the other day by manually writing out each element of the class to a String and it occurred to me that using reflection it might be possible to create a generic toString() method that could work on ALL classes. I.E. it would figure out the field names and values and send them out to a String.
Getting the field names is fairly simple, here is what a co-worker came up with:
public static List initFieldArray(String className) throws ClassNotFoundException {
Class c = Class.forName(className);
Field field[] = c.getFields();
List<String> classFields = new ArrayList(field.length);
for (int i = 0; i < field.length; i++) {
String cf = field[i].toString();
classFields.add(cf.substring(cf.lastIndexOf(".") + 1));
}
return classFields;
}
Using a factory I could reduce the performance overhead by storing the fields once, the first time the toString() is called. However finding the values could be a lot more expensive.
Due to the performance of reflection this may be more hypothetical then practical. But I am interested in the idea of reflection and how I can use it to improve my everyday programming.

Apache commons-lang ReflectionToStringBuilder does this for you.
import org.apache.commons.lang3.builder.ReflectionToStringBuilder
// your code goes here
public String toString() {
return ReflectionToStringBuilder.toString(this);
}

Another option, if you are ok with JSON, is Google's GSON library.
public String toString() {
return new GsonBuilder().setPrettyPrinting().create().toJson(this);
}
It's going to do the reflection for you. This produces a nice, easy to read JSON file. Easy-to-read being relative, non tech folks might find the JSON intimidating.
You could make the GSONBuilder a member variable too, if you don't want to new it up every time.
If you have data that can't be printed (like a stream) or data you just don't want to print, you can just add #Expose tags to the attributes you want to print and then use the following line.
new GsonBuilder()
.setPrettyPrinting()
.excludeFieldsWithoutExposeAnnotation()
.create()
.toJson(this);

W/reflection, as I hadn't been aware of the apache library:
(be aware that if you do this you'll probably need to deal with subobjects and make sure they print properly - in particular, arrays won't show you anything useful)
#Override
public String toString()
{
StringBuilder b = new StringBuilder("[");
for (Field f : getClass().getFields())
{
if (!isStaticField(f))
{
try
{
b.append(f.getName() + "=" + f.get(this) + " ");
} catch (IllegalAccessException e)
{
// pass, don't print
}
}
}
b.append(']');
return b.toString();
}
private boolean isStaticField(Field f)
{
return Modifier.isStatic(f.getModifiers());
}

If you're using Eclipse, you may also have a look at JUtils toString generator, which does it statically (generating the method in your source code).

You can use already implemented libraries, as ReflectionToStringBuilder from Apache commons-lang. As was mentioned.
Or write smt similar by yourself with reflection API.
Here is some example:
class UniversalAnalyzer {
private ArrayList<Object> visited = new ArrayList<Object>();
/**
* Converts an object to a string representation that lists all fields.
* #param obj an object
* #return a string with the object's class name and all field names and
* values
*/
public String toString(Object obj) {
if (obj == null) return "null";
if (visited.contains(obj)) return "...";
visited.add(obj);
Class cl = obj.getClass();
if (cl == String.class) return (String) obj;
if (cl.isArray()) {
String r = cl.getComponentType() + "[]{";
for (int i = 0; i < Array.getLength(obj); i++) {
if (i > 0) r += ",";
Object val = Array.get(obj, i);
if (cl.getComponentType().isPrimitive()) r += val;
else r += toString(val);
}
return r + "}";
}
String r = cl.getName();
// inspect the fields of this class and all superclasses
do {
r += "[";
Field[] fields = cl.getDeclaredFields();
AccessibleObject.setAccessible(fields, true);
// get the names and values of all fields
for (Field f : fields) {
if (!Modifier.isStatic(f.getModifiers())) {
if (!r.endsWith("[")) r += ",";
r += f.getName() + "=";
try {
Class t = f.getType();
Object val = f.get(obj);
if (t.isPrimitive()) r += val;
else r += toString(val);
} catch (Exception e) {
e.printStackTrace();
}
}
}
r += "]";
cl = cl.getSuperclass();
} while (cl != null);
return r;
}
}

Not reflection, but I had a look at generating the toString method (along with equals/hashCode) as a post-compilation step using bytecode manipulation. Results were mixed.

Here is the Netbeans equivalent to Olivier's answer; smart-codegen plugin for Netbeans.