Develop Reference

Out params not clearing on stored procedure call

My problem is as follows:
My service loops over items that are passed as args. For each item, i make two calls. My first price call gives me 9999 which means nothing was returned. That's fine - that's possible. My stock call works perfectly and i get the correct stock value returned. On the second iteration, my price call returns the same value as the previous stock call.
So, i get 9999 for price, then 150 for stock, then 150 for price. What's throwing me is that the price out parm is 6th, whereas the stock out parm is 8th. No idea how it would retain that value in a different position.
It seems that my jdbctemplate isn't being cleared or it's storing previous out params. Here's the code involved:
MyService.java
#Service
public class MyService extends BaseService implements MyInterface{
protected static final Logger logger = LoggerFactory.getLogger(MyService.class);
#Autowired
private MyDAO myDAO;
public myResponse checkOrder(args...)
{
for(something in args){
// PRICE
// Grab price data
LinkedHashMap<String, Object> priceCallInParams = new LinkedHashMap<String, Object>();
priceCallInParams .put("param1", "param1val");
priceCallInParams .put("param2", "param2val");
priceCallInParams .put("param3", "param3val");
priceCallInParams .put("param4", "param4val");
priceCallInParams .put("param5", "param5val");
LinkedHashMap<String, Object> priceCallOutParams = new LinkedHashMap<String, Object>();
priceCallOutParams .put("price", "0");
logger.debug("Getting data...");
Map<String, Object> priceData = new HashMap<String, Object>();
priceData = myDAO.checkPrice(priceCallInParams , priceCallOutParams );
BigDecimal unitPrice = new BigDecimal(9999);
if (!priceData .get("PRCE").toString().trim().equals("")){
unitPrice = new BigDecimal(priceData.get("PRCE").toString().trim());
}
System.out.println("PRC - "+unitPrice);
// AVAILABLE STOCK
// Grab check stock data
LinkedHashMap<String, Object> checkStockInParms = new LinkedHashMap<String, Object>();
checkStockInParms.put("param1", "param1val");
checkStockInParms.put("param2", "param2val");
checkStockInParms.put("param3", "param3val");
checkStockInParms.put("param4", "param4val");
checkStockInParms.put("param5", "param5val");
checkStockInParms.put("param6", "param6val");
checkStockInParms.put("REQQTY", "123");
LinkedHashMap<String, Object> checkStockOutParms = new LinkedHashMap<String, Object>();
checkStockOutParms .put("AVAILQTY", "0");
checkStockOutParms .put("NEXTDUE"," ");
checkStockOutParms .put("NEXTQTY","0");
logger.debug("Getting data...");
Map<String, Object> checkStockDat = new HashMap<String, Object>();
checkStockDat = myDAO.checkStock(checkStockInParms , checkStockOutParms );
// Output quantity
int AvailQTY = Integer.valueOf(checkStockDat.get("AVAILQTY").toString().trim());
if (reqBIT.getRequestedQuantity()>AvailQTY) {
resBIT.setConfirmedQuantity(AvailQTY);
}
else {
resBIT.setConfirmedQuantity(reqBIT.getRequestedQuantity());
}
}
}
}
MyDAO.java
#Component
public class MyDAO extends BaseDAO{
protected static final Logger logger = LoggerFactory.getLogger(OrderDAO.class);
public Map<String, Object> checkStock(LinkedHashMap<String, Object> inparms, LinkedHashMap<String, Object> outparms){
StringBuilder builtSQL = new StringBuilder();
builtSQL.append("CALL ");
builtSQL.append("checkstock ");
// just generates our param string (?,?,?...)
builtSQL.append(DataUtilities.genParmPlaceholderStringFromTotal(inparms.size()+outparms.size()));
return executeStoredProcedure(builtSQL.toString(), inparms, outparms);
}
public Map<String, Object> checkPrice(LinkedHashMap<String, Object> inparms, LinkedHashMap<String, Object> outparms){
logger.debug("CheckPrcc Initiated");
StringBuilder builtSQL = new StringBuilder();
builtSQL.append("CALL ");
builtSQL.append("checkprice ");
// just generates our param string (?,?,?...)
builtSQL.append(DataUtilities.genParmPlaceholderStringFromTotal(inparms.size()+outparms.size()));
return executeStoredProcedure(builtSQL.toString(), inparms, outparms);
}
}
BaseDAO.java
public class BaseDAO{
#Autowired
protected JdbcTemplate jdbcTemplate;
protected static final Logger logger = LoggerFactory.getLogger(BaseDAO.class);
protected Map<String, Object> executeStoredProcedure(String SQL, LinkedHashMap<String, Object> inParams, LinkedHashMap<String, Object> outParams){
Map<String, Object> result = new HashMap<String, Object>();
List<SqlParameter> declaredParameters = new ArrayList<SqlParameter>();
for (Map.Entry<String, Object> entry : inParams.entrySet()) {
declaredParameters.add(new SqlParameter(entry.getKey().toString(), Types.CHAR));
}
for (Map.Entry<String, Object> entry : outParams.entrySet()) {
declaredParameters.add(new SqlOutParameter(entry.getKey().toString(), Types.CHAR));
}
result = jdbcTemplate.call(new CallableStatementCreator() {
public CallableStatement createCallableStatement(Connection connection)
throws SQLException {
CallableStatement callableStatement = connection.prepareCall(SQL);
int index = 0;
for (Map.Entry<String, Object> entry : inParams.entrySet()) {
index++;
callableStatement.setString(index, entry.getValue().toString());
}
for (Map.Entry<String, Object> entry : outParams.entrySet()) {
index++;
callableStatement.registerOutParameter(index, Types.CHAR);
}
return callableStatement;
}
}, declaredParameters);
return result;
}
}
My service is invoked from my rest controller, which pass the args (if that matters).
I've been racking my brain and can't find any information regarding this issue. I'm new to spring boot and Java. I don't believe i'm doing something too egregious.

In our situation, this was being caused our i-series. If no data is present to return, the system still returns 10 chars from memory - being the last value it just returned. The solution is to always populate the return value to clear the memory.
Not spring-boot after all!

serialize map of maps to dyanmodb to json

To attribute Map below in a class that i want to save and read from Dyanmodb, using DynamoDBMapper.
Map<String, Map<String, Transition>> twf;
public class Transition {
public String fst;
public Permission pm;
public List<Action> ac;
}
public class Action {
private String mdl;
private String dsc;
private String nm;
// email address or any other data
private Map<String, String> data;
}
i have tried DynamoDBTypeConverted to convert to String, that results in json string that has " escaped as \" and unreadable in dyanmodb. I wanted to store as json
I implemented with understanding that Dyanmodb supports Map, but i still get error :
Exception processing message: not supported; requires #DynamoDBTyped or #DynamoDBTypeConverted
public class TimeSheetWorkFlowConverter implements
DynamoDBTypeConverter<Map<String, Object>, Map<String, Map<String, Transition>>> {
#Override
public Map convert(Map<String, Map<String, Transition>> object) {
// Map obj = mapper.readValue(object, Map.class);
String newJson = null;
Map objectJson = null;
try {
newJson = mapper.writeValueAsString(object);
objectJson = mapper.readValue(newJson, Map.class);
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return objectJson;
}
#SuppressWarnings("unchecked")
#Override
public Map<String, Map<String, Transition>> unconvert(Map<String, Object> object) {
Map<String, Map<String, Transition>> wf = new HashMap<>();
if (object != null && !object.isEmpty())
for (Entry<String, Object> entry : object.entrySet()) {
String key = entry.getKey();
Map<String, Transition> value = mapTransition(entry.getValue());
wf.put(key, value);
}
return wf;
}

populate hashmap from hibernate query

public List<UMRDTO> getDocumentLink(Session session)
{
List<UMRDTO> documentationList = null;
Query query = null;
query = session.createQuery(UMRSQLInt.DOCUMENTATION_LIST);
documentationList = query.list();
return documentationList;
}
Whenever I restart my app all the hashmap are empty and no data is present that in inputed earlier
I need to get the list i.e objectName , objectType and the documentationLink from the above query and then put the data (objectName,documentationLink) in the HashMap if the objectName is Domainname then the data to be put in domainDocumentationMap or if it is combo then in domainComboDocumentationMap
private static Map<String, String> domainDocumentationMap = null;
private static Map<String, String> domainComboDocumentationMap = null;
static
{
domainDocumentationMap = new HashMap<String, String>();
domainComboDocumentationMap = new HashMap<String, String>();
}
public static Map<String, String> getDomainDocumentationMap(){
return domainDocumentationMap;
}
public static void setDomainDocumentationMap(String objectName, String documentationLink) {
MMTUtil.domainDocumentationMap.put(objectName, documentationLink);
}
what query shall i write?

Java Hashmap to JavaFX Treeview and Back?

I have a nested HashMap which looks like this:
Map<String,Object> myMap = new HashMap<String,Object>();
This myMap is nested, Like:
String key => String val
String key => String val
String key => Map<String,Object> val
And then that value may contain another similar Map<String,Object>.
I do not expect it to be nested more than 3 levels.
The leafs or last values are always String.
Now I'm trying to make a way to edit this HashMap in a JavaFX GUI.
From what I have learnt so far,
the best way seems like making a editable JavaFX TreeView
and somehow translating the Map to a TreeView and back.
So far I'm thinking
TreeMap<String, Object> treeMap = new TreeMap<String, Object>();
treeMap.putAll(myMap);
And then somehow translating that TreeMap to a JavaFX TreeView.
But I can not figure out how to proceed.
Another headache is that after user edits I need to translate it all back to a HashMap such as the original myMap. Although sorting / sequence is not required.

Create a suitable class to represent the map entry. Since you need to modify the Map, you need to store key and Map in that class.
If you use TextFieldTreeCell as cell type, the StringConverter can be used to modify the source data structure on a edit:
private static TreeItem<MapItem> createTree(Map<String, Object> map) {
TreeItem<MapItem> result = new TreeItem<>();
for (Map.Entry<String, Object> entry : map.entrySet()) {
result.getChildren().add(createTree(map, entry));
}
return result;
}
private static TreeItem<MapItem> createTree(Map<String, Object> map, Map.Entry<String, Object> entry) {
MapItem mi = new MapItem(map, entry.getKey());
TreeItem<MapItem> result = new TreeItem<>(mi);
Object value = entry.getValue();
if (value instanceof Map) {
Map<String, Object> vMap = (Map<String, Object>)value;
// recursive creation of subtrees for map entries
for (Map.Entry<String, Object> e : vMap.entrySet()) {
result.getChildren().add(createTree(vMap, e));
}
} else {
result.getChildren().add(new TreeItem<>(new MapItem(null, value.toString())));
}
return result;
}
private static class MapItem {
private final Map<String, Object> map;
private final String value;
public MapItem(Map<String, Object> map, String value) {
this.map = map;
this.value = value;
}
}
private static class Converter extends StringConverter<MapItem> {
private final TreeCell<MapItem> cell;
public Converter(TreeCell<MapItem> cell) {
this.cell = cell;
}
#Override
public String toString(MapItem object) {
return object == null ? null : object.value;
}
#Override
public MapItem fromString(String string) {
MapItem mi = cell.getItem();
if (mi != null) {
TreeItem<MapItem> item = cell.getTreeItem();
if (item.isLeaf()) {
MapItem parentItem = item.getParent().getValue();
// modify value in parent map
parentItem.map.put(parentItem.value, string);
mi = new MapItem(mi.map, string);
} else if (!mi.map.containsKey(string)) {
// change key of mapping, if there is no mapping for the new key
mi.map.put(string, mi.map.remove(mi.value));
mi = new MapItem(mi.map, string);
}
}
return mi;
}
}
#Override
public void start(Stage primaryStage) {
Map<String, Object> map = new HashMap<>();
map.put("a", "b");
Map<String, Object> inner = new HashMap<>();
map.put("c", inner);
inner.put("d", "e");
Map<String, Object> inner2 = new HashMap<>();
inner.put("f", inner2);
inner2.put("g", "h");
inner2.put("i", "j");
TreeView<MapItem> treeView = new TreeView<>(createTree(map));
treeView.setEditable(true);
treeView.setShowRoot(false);
treeView.setCellFactory(t -> {
TextFieldTreeCell<MapItem> cell = new TextFieldTreeCell<>();
cell.setConverter(new Converter(cell));
return cell;
});
Button btn = new Button("Print Map");
btn.setOnAction((ActionEvent event) -> {
System.out.println(map);
});
VBox root = new VBox(10, btn, treeView);
Scene scene = new Scene(root);
primaryStage.setScene(scene);
primaryStage.show();
}

There is not build-in method that would convert:
either Map directly to TreeView
or TreeMap to TreeView
Moreover, If you see the structure of Map<?,?>, we can see that it is a combination of key, value pair whereas TreeView<?> consists of only value, like that of Collection interface. So It's not possible to insert key, value pair in TreeView. However you can insert only values from Map.
The best you can do is define a new data structure like this:
public class YourCustomDataStructure extends TreeItem<String> {
...
/*
Now you can define methods that will convert `List`s directly to `YourCustomDataStructure`.
You can even define method to convert `Map` values to `YourCustomDataStructure`.
*/
public boolean addAll(Map map) {
//your implementation to convert map to TreeItem
}
public boolean addAll(List list) {
//your implementation to convert list to TreeItem
}
}
Now convert your list or map to YourCustomDataStructure using addAll() method from previous step.
List<Object> list = getListFromSomewhere();
YourCustomDataStructure<String> customList = new YourCustomDataStructure<String>("customList Node");
customList.getChildren().addAll(list);
Now since YourCustomDataStructure extends TreeItem so it's object's can be directly passed to TreeView's constructor and they will be automatically converted to TreeView.
TreeView<String> treeView = new TreeView<String>(customList);
P.S.: I know defining new data structure and all the methods will require lots of efforts at initial level, but once those methods are defined, then it will become too easy to convert TreeView to Map and vice versa.

How do I access nested HashMaps in Java?

I have a HashMap in Java, the contents of which (as you all probably know) can be accessed by
HashMap.get("keyname");
If a have a HashMap inside another HashMap i.e. a nested HashMap, how would i access the contents? Can i do this like this, inline:
HashMap.get("keyname").get("nestedkeyname");
Thank you.

You can do it like you assumed. But your HashMap has to be templated:
Map<String, Map<String, String>> map =
new HashMap<String, Map<String, String>>();
Otherwise you have to do a cast to Map after you retrieve the second map from the first.
Map map = new HashMap();
((Map)map.get( "keyname" )).get( "nestedkeyname" );

You can get the nested value by repeating .get(), but with deeply nested maps you have to do a lot of casting into Map. An easier way is to use a generic method for getting a nested value.
Implementation
public static <T> T getNestedValue(Map map, String... keys) {
Object value = map;
for (String key : keys) {
value = ((Map) value).get(key);
}
return (T) value;
}
Usage
// Map contents with string and even a list:
{
"data": {
"vehicles": {
"list": [
{
"registration": {
"owner": {
"id": "3643619"
}
}
}
]
}
}
}
List<Map> list = getNestedValue(mapContents, "data", "vehicles", "list");
Map first = list.get(0);
String id = getNestedValue(first, "registration", "owner", "id");

Yes.
See:
public static void main(String args[]) {
HashMap<String, HashMap<String, Object>> map = new HashMap<String, HashMap<String,Object>>();
map.put("key", new HashMap<String, Object>());
map.get("key").put("key2", "val2");
System.out.println(map.get("key").get("key2"));
}

If you plan on constructing HashMaps with variable depth, use a recursive data structure.
Below is an implementation providing a sample interface:
class NestedMap<K, V> {
private final HashMap<K, NestedMap> child;
private V value;
public NestedMap() {
child = new HashMap<>();
value = null;
}
public boolean hasChild(K k) {
return this.child.containsKey(k);
}
public NestedMap<K, V> getChild(K k) {
return this.child.get(k);
}
public void makeChild(K k) {
this.child.put(k, new NestedMap());
}
public V getValue() {
return value;
}
public void setValue(V v) {
value = v;
}
}
and example usage:
class NestedMapIllustration {
public static void main(String[] args) {
NestedMap<Character, String> m = new NestedMap<>();
m.makeChild('f');
m.getChild('f').makeChild('o');
m.getChild('f').getChild('o').makeChild('o');
m.getChild('f').getChild('o').getChild('o').setValue("bar");
System.out.println(
"nested element at 'f' -> 'o' -> 'o' is " +
m.getChild('f').getChild('o').getChild('o').getValue());
}
}

As others have said you can do this but you should define the map with generics like so:
Map<String, Map<String, String>> map = new HashMap<String, Map<String,String>>();
However, if you just blindly run the following:
map.get("keyname").get("nestedkeyname");
you will get a null pointer exception whenever keyname is not in the map and your program will crash. You really should add the following check:
String valueFromMap = null;
if(map.containsKey("keyname")){
valueFromMap = map.get("keyname").get("nestedkeyname");
}

Yes, if you use the proper generic type signature for the outer hashmap.
HashMap<String, HashMap<String, Foo>> hm = new HashMap<String, HashMap<String, Foobar>>();
// populate the map
hm.get("keyname").get("nestedkeyname");
If you're not using generics, you'd have to do a cast to convert the object retrieved from the outer hash map to a HashMap (or at least a Map) before you could call its get() method. But you should be using generics ;-)

I prefer creating a custom map that extends HashMap. Then just override get() to add extra logic so that if the map doesnt contain your key. It will a create a new instance of the nested map, add it, then return it.
public class KMap<K, V> extends HashMap<K, V> {
public KMap() {
super();
}
#Override
public V get(Object key) {
if (this.containsKey(key)) {
return super.get(key);
} else {
Map<K, V> value = new KMap<K, V>();
super.put((K)key, (V)value);
return (V)value;
}
}
}
Now you can use it like so:
Map<Integer, Map<Integer, Map<String, Object>>> nestedMap = new KMap<Integer, Map<Integer, Map<String, Object>>>();
Map<String, Object> map = (Map<String, Object>) nestedMap.get(1).get(2);
Object obj= new Object();
map.put(someKey, obj);

I came to this StackOverflow page looking for a something ala valueForKeyPath known from objc. I also came by another post - "Key-Value Coding" for Java, but ended up writing my own.
I'm still looking for at better solution than PropertyUtils.getProperty in apache's beanutils library.
Usage
Map<String, Object> json = ...
public String getOptionalFirstName() {
return MyCode.getString(json, "contact", "firstName");
}
Implementation
public static String getString(Object object, String key0, String key1) {
if (key0 == null) {
return null;
}
if (key1 == null) {
return null;
}
if (object instanceof Map == false) {
return null;
}
#SuppressWarnings("unchecked")
Map<Object, Object> map = (Map<Object, Object>)object;
Object object1 = map.get(key0);
if (object1 instanceof Map == false) {
return null;
}
#SuppressWarnings("unchecked")
Map<Object, Object> map1 = (Map<Object, Object>)object1;
Object valueObject = map1.get(key1);
if (valueObject instanceof String == false) {
return null;
}
return (String)valueObject;
}

import java.util.*;
public class MyFirstJava {
public static void main(String[] args)
{
Animal dog = new Animal();
dog.Info("Dog","Breezi","Lab","Chicken liver");
dog.Getname();
Animal dog2= new Animal();
dog2.Info("Dog", "pumpkin", "POM", "Pedigree");
dog2.Getname();
HashMap<String, HashMap<String, Object>> dogs = new HashMap<>();
dogs.put("dog1", new HashMap<>() {{put("Name",dog.name);
put("Food",dog.food);put("Age",3);}});
dogs.put("dog2", new HashMap<>() {{put("Name",dog2.name);
put("Food",dog2.food);put("Age",6);}});
//dogs.get("dog1");
System.out.print(dogs + "\n");
System.out.print(dogs.get("dog1").get("Age"));
}
}

Example Map:
{
"data": {
"userData": {
"location": {
"city": "Banja Luka"
}
}
}
}
Implementation:
public static Object getValueFromMap(final Map<String, Object> map, final String key) {
try {
final String[] tmpKeys = key.split("\\.");
Map<String, Object> currentMap = map;
for (int i = 0; i < tmpKeys.length - 1; i++) {
currentMap = (Map<String, Object>) currentMap.get(tmpKeys[i]);
}
return currentMap.get(tmpKeys[tmpKeys.length - 1]);
} catch (Exception exception) {
return null;
}
}
Usage:
final Map<String, Object> data = new HashMap<>();
final Map<String, Object> userData = new HashMap<>();
final Map<String, Object> location = new HashMap<>();
location.put("city", "Banja Luka");
userData.put("location", location);
data.put("userData", userData);
System.out.println(getValueFromMap(data, "userData.location.city"));
Result:
Banja Luka
Process finished with exit code 0

I hit this discussion while trying to figure out how to get a value from a nested map of unknown depth and it helped me come up with the following solution to my problem. It is overkill for the original question but maybe it will be helpful to someone that finds themselves in a situation where you have less knowledge about the map being searched.
private static Object pullNestedVal(
Map<Object, Object> vmap,
Object ... keys) {
if ((keys.length == 0) || (vmap.size() == 0)) {
return null;
} else if (keys.length == 1) {
return vmap.get(keys[0]);
}
Object stageObj = vmap.get(keys[0]);
if (stageObj instanceof Map) {
Map<Object, Object> smap = (Map<Object, Object>) stageObj;
Object[] skeys = Arrays.copyOfRange(keys, 1, keys.length);
return pullNestedVal(smap, skeys);
} else {
return null;
}
}