Develop Reference

Java - SnakeYaml | Get all keys of a file

First of all, I have been reading a few posts about keys, but none of them asks my question on how to get ALL keys of a yaml file, only on how to get an specific key.
Now, I want to create a file updater, it works, but it only updates the first keys, without the "sub-keys", here is the code:
InputStream resource = getClass().getClassLoader().getResourceAsStream(dir);
Map<String, Object> data = new Yaml().load(resource);
for(String str : data.keySet()) {
DBot.getConsole().log(str);
if(!contains(str)) {
set(str, data.get(str));
}
}
The file looks like this:
Features.Example.StringA
Features.Example.StringB
With points being spaces to make them sub-keys (stack overflow puts them on a single line, sorry)
Now the thing is, the updater will only work if "Features" is deleted, also, the debug will only print "Features", meaning that only the first key is on the key set, how can I get all keys?

I have finally found how to return a Set with every key separated by a ".", Bukkit/Spigot developers might be familiar with this. First of all, you have to create a class like this:
import java.util.HashSet;
import java.util.Map;
import java.util.Set;
public class YamlKeys {
private static Set<String> keys = new HashSet<String>();
private static String path = "";
YamlKeys(Map<?, ?> data) {
getKeysRecursive(data);
}
private void getKeysRecursive(final Map<?, ?> data) {
for(Object key : data.keySet()) {
final Object value = data.get(key);
if(key instanceof String) {
if(path.length() == 0) {
path = (String)key; // If the key is the first on the path, don't include separator.
} else {
path = path+"."+(String)key; // Here is the separator, you can change it.
}
}
if(value instanceof Map) {
getKeysRecursive((Map<?, ?>) value); // A value map has been found, recursing with that value.
} else {
keys.add(path); // No more maps have been found, we can add the path and stop recursing.
if(path.contains(".")) {
path = path.substring(0, path.lastIndexOf(".")); // Removing last key, so if a value contains more than one key, it won't appear again.
}
}
}
path = ""; // This is important, reset the path.
}
Set<String> getKeys() {
return keys;
}
}
Then, to call it and select if you want to get deep keys or "normal" keys, you can create a method like this:
public Set<String> getKeys(boolean deep) {
Map<String, Object> data = new Yaml().load(inStream);
if(!deep) {
return data.keySet();
} else {
return new YamlKeys(data).getKeys();
}
}
To test it, we can use the following code:
new YamlKeys(data).getKeys().stream().forEach(key -> System.out.println(key));
With this file:
FirstKey:
SecondKey:
Enabled: true
Text: "Some text"
AnotherKey:
AValue: true
AnotherTest:
Enabled: false
Value: true
It returns this output:
FirstKey.SecondKey.AnotherKey.AValue
FirstKey.SecondKey.Enabled
FirstKey.SecondKey.Text
Value
AnotherTest.Enabled
Thanks to roby for telling me about recursion.

SnakeYAML is decoding the yaml into a recursive data structure. For example:
public static void main(String[] args) {
String yaml = "a:\n b: \n c: \"string\"";
Map<String, Object> data = new Yaml().load(yaml);
System.out.println(data);
}
prints out:
{a={b={c=string}}}
Which is a Map<String, Map<String, Map<String, String>>>.
To show how you can work with it recursively, here's how you can print out some of that detail.
private static void printMapRecursive(final Map<?, ?> data) {
for(Object key : data.keySet()) {
System.out.println("key " + key + " is type " + key.getClass().getSimpleName());
final Object value = data.get(key);
if(value instanceof Map){
System.out.println("value for " + key + " is a Map - recursing");
printMapRecursive((Map<?, ?>) value);
} else {
System.out.println("value " + value + " for " + key + " is type " + value.getClass());
}
}
}
Which you can call with printMapRecursive(data); and see output:
key a is type String
value for a is a Map - recursing
key b is type String
value for b is a Map - recursing
key c is type String
value string for c is type class java.lang.String
and an example of recursively transforming the keys:
private static Map<?, ?> mutateMapRecursive(final Map<?, ?> data,
Function<String, String> keyFunction) {
Map<Object, Object> result = new HashMap<>();
for (Object key : data.keySet()) {
final Object value = data.get(key);
if(key instanceof String){
key = keyFunction.apply((String) key);
}
if (value instanceof Map) {
result.put(key, mutateMapRecursive((Map<?, ?>) value, keyFunction));
}
else {
result.put(key, value);
}
}
return result;
}
called like:
final Map<?, ?> transformed = mutateMapRecursive(data, (key) -> "prefix_" + key);
System.out.println(transformed);
emits:
{prefix_a={prefix_b={prefix_c=string}}}

How do you initialize the MapScanCursor in Lettuce Redis client library?

I am trying to do an HSCAN using Lettuce's synchronous commands. The problem is that I can't figure out the correct way of initializing the MapScanCursor. I've had no success with the constructor, and MapScanCursor.INITIAL gives type ScanCursor (no luck casting that to MapScanCursor either).
Here is an example:
RedisClient redisClient = RedisClient.create("redis://" + url + ":" + port);
RedisHashCommands<String, String> redisCommands = redisClient.connect().sync();
List<String> fields = new LinkedList<>();
MapScanCursor<String, String> scanCursor = ?
do {
scanCursor = redisCommands.hscan(key, scanCursor);
fields.addAll(scanCursor.getMap().keySet());
} while (!scanCursor.isFinished());
How should I initialize "scanCursor"?

You have two options:
To answer your question, initialize scanCursor with just hscan(key).
MapScanCursor<String, String> scanCursor = null;
do {
if (scanCursor == null) {
scanCursor = redisCommands.hscan(key);
} else {
scanCursor = redisCommands.hscan(key, scanCursor);
}
fields.addAll(scanCursor.getMap().keySet());
} while (!scanCursor.isFinished());
Alternatively, you can use ScanIterator (see Lettuce 4.4) which is an Iterator and covers the complexity of Redis SCAN usage:
ScanIterator<KeyValue<String, String>> iterator = ScanIterator.hscan(redisCommands, key);
while (iterator.hasNext()) {
KeyValue<String, String> next = iterator.next();
// …
}
Update
Updated the do…while-based approach according to tcfritchman's comment.

Unable to Print matching hashmap keys in Java using Android Studio

I am trying to iterate two hash maps and print the keys that are matching in both of them.Although both of the hash maps have got matching elements it is consistently saying "no match found".
Below posted is my code.
try {
String s = new String(data);
String string = new String(input_bytes);
StringTokenizer stringTokenizer = new StringTokenizer(s);
StringTokenizer input_stringTokenizer = new StringTokenizer(string);
while(stringTokenizer.hasMoreTokens())
{
map.put(stringTokenizer.nextToken(), stringTokenizer.nextToken());
}
while(input_stringTokenizer.hasMoreTokens())
{
input_map.put(input_stringTokenizer.nextToken(),
input_stringTokenizer.nextToken());
}}
catch (Exception e1) {
e1.printStackTrace();
}}
Iterator input1 = map.entrySet().iterator();
Iterator input_2 = input_map.entrySet().iterator();
while (input_2.hasNext() && input1.hasNext()) {
Map.Entry input_val1 = (Map.Entry) input1.next();
Map.Entry input_val2 = (Map.Entry) input_2.next();
String temp = input_val1.getKey().toString().substring(input_val1.getKey().toString().lastIndexOf("\\") + 1);
String temp_2 = input_val2.getKey().toString().substring(input_val2.getKey().toString().lastIndexOf("\\") + 1);
if(temp.equals(temp_2))
{
System.out.println("element matched");
}
else
{
System.out.println("no match found!");
}
}
My input files are "data" and "input_bytes"
The path in these files is the "key" and the hash is the "value" of the hashmap.
For effective matching i have trimmed the path such that it gives me only the element after the last slash.
"temp" variable in the code will print in the following way :
com.example.android.notepad_4.4.2-eng.build.20150616.1901504.apk ﹕
com.facebook.orca_34.0.0.22.2114.apk
com.android.contacts_4.4.2-eng.build.20150616.1901504.apk
com.amazon.venezia_release-13.0003.844.1C_6430003104.apk
com.android.deskclock_3.0.04.apk
com.google.android.apps.photos_1.0.0.943910814.apk
apuslauncher-2.apk
com.android.vending-v5.8.11-80381100-Android-2.3.apk
net.sylark.apkextractor_1.0.54.apk
Here is how my "data" file look like:
C:\Users\rishii\Desktop\input_3\com.amazon.venezia_release-
13.0003.844.1C_6430003104.apk
266796d1b8e2e016753ee3bf1b50e591
C:\Users\rishii\Desktop\input_3\com.android.browser_4.4.2-
eng.build.20150616.1901504.apk
4aa2091b0e21fc655e19d07e2ae20982
C:\Users\rishii\Desktop\input_3\com.android.calculator2_4.4.2-
eng.build.20150616.1901504.apk
85313ccbd39a43952906b70b941d321b
C:\Users\rishii\Desktop\input_3\com.android.calendar_4.4.2-
eng.build.20150616.1901504.apk
3c85cb87f2e134a4157e5f3747e4df1b
Here is my "input_bytes" file looks like:
C:\Users\rishii\Desktop\baal\com.amazon.venezia_release-
13.0003.844.1C_6430003104.apk
266796d1b8e2e016753ee3bf1b50e591
C:\Users\rishii\Desktop\baal\com.android.browser_4.4.2-
eng.build.20150616.1901504.apk
4aa2091b0e21fc655e19d07e2ae20982
C:\Users\rishii\Desktop\baal\com.android.calculator2_4.4.2-
eng.build.20150616.1901504.apk
85313ccbd39a43952906b70b941d321b
C:\Users\rishii\Desktop\baal\com.android.calendar_4.4.2-
eng.build.20150616.1901504.apk
3c85cb87f2e134a4157e5f3747e4df1b
C:\Users\rishii\Desktop\baal\com.android.camera2_2.0.002-
eng.build.ef73894.060315_142358-704.apk
482205cda6991f89fb35311dea668013
If you can see there are some matches in both the files.Any help would be highly appreciated.

Here's a much simpler way to check if they contain the same keys:
public void findSameKeys(Map<String, String> map1, Map<String, String> map2) {
for (String key : map1.keySet()) {
if (map2.containsKey(key)) {
System.out.println("Matching key: " + key);
}
}
}
The containsKey() method is very useful here.

Adding entries to LinkedList inside ConcurrentHashMap not working

I have a ConcurrentHashMap that contains a string as a key and LinkedList as a value. The size of the list should not be more than 5. I am trying to add some elements to the list but when I print out the Map I see only the last added element. Here is my code:
private ConcurrentHashMap<String, LinkedList<Date>> userDisconnectLogs = new ConcurrentHashMap<String, LinkedList<Date>>();
public void addNewDateEntry(String userId, LinkedList<Date> timeStamps) {
if (timeStamps.size() >= 5) {
timeStamps.poll();
timeStamps.add(new Date());
userDisconnectLogs.put(userId, timeStamps);
} else {
timeStamps.add(new Date());
userDisconnectLogs.put(userId, timeStamps);
}
for (Entry<String, LinkedList<Date>> entry : userDisconnectLogs
.entrySet()) {
String key = entry.getKey().toString();
;
LinkedList<Date> value = entry.getValue();
System.out.println("key: " + key + " value: " + value.size());
}
}
Thank you!

Here for hashMap key must be unique. And from this code it seems key is always same so all the time it will overrite the data.

Populate ComboBox with HashMap?

I'm trying populate a combobox of vaadin7 with informations hashmap. I create a class that return a HashMap when I get the return I use a for each to populate this combobox but does show me only numbers and not the keys and values of hashmap.
I'm trying this.
/** states of brasil class */
public class EstadosBrasil {
private static final HashMap<String, String> uf = new HashMap();
/** return all states of brasil */
public static HashMap<String, String> getEstados(){
uf.put("AC", "AC");
uf.put("AL", "AL");
uf.put("AM", "AM");
uf.put("AP", "AP");
uf.put("BA", "BA");
uf.put("CE", "CE");
uf.put("DF", "DF");
uf.put("ES", "ES");
uf.put("FN", "FN");
uf.put("GO", "GO");
uf.put("MA", "MA");
uf.put("MG", "MG");
uf.put("MS", "MS");
uf.put("MT", "MT");
uf.put("PA", "PA");
uf.put("PB", "PB");
uf.put("PE", "PE");
uf.put("PI", "PI");
uf.put("PR", "PR");
uf.put("RJ", "RJ");
uf.put("RN", "RN");
uf.put("RO", "RO");
uf.put("RR", "RR");
uf.put("RS", "RS");
uf.put("SC", "SC");
uf.put("SE", "SE");
uf.put("SP", "SP");
uf.put("TO", "TO");
return uf;
}
}
// my combobox
private ComboBox comboEstado;
comboEstado = new ComboBox("States");
comboEstado.setWidth("100px");
HashMap<String, String> estados = EstadosBrasil.getEstados();
for(Entry<String, String> e : estados.entrySet()){
Object obj = comboEstado.addItem();
comboEstado.setItemCaption(e.getKey(), e.getValue());
comboEstado.setValue(obj);
}
mainLayout.addComponent(comboEstado);
Any idea ?
thanks

Change-
Object obj = comboEstado.addItem();
comboEstado.setItemCaption(e.getKey(), e.getValue());
comboEstado.setValue(obj);
To-
comboEstado.addItem(e.getKey());
comboEstado.setItemCaption(e.getKey(), e.getValue());
If you want both key and value pair to appear, something like this can be done-
comboEstado.setItemCaption(e.getKey(), e.getKey() + " : " + e.getValue());
By the way, I hope you are going to change the values. If both key and value are the same, you can just use a Set.

In the new Vaadin 8 API, there is no addItems method on Combobox.
The code below works:
Map<String, String> map = new HashMap<>();
ComboBox combobox = new ComboBox<>("My Combobox");
combobox.setItems(map);
combobox.setItemCaptionGenerator(new ItemCaptionGenerator() {
#Override
public String apply(Object o) {
HashMap m = (HashMap) o;
return m.keySet().stream().findFirst().get().toString();
}
});