I have a nested HashMap (outer_map), which has another HashMap inside of it as a value (inner_map), such implemented as
Map<String, HashMap<String, String>> outer_map = new HashMap<String, HashMap<String, String>>();
Map<String, String> inner_map = new HashMap<String, String>();
The figure below illustrates the whole structures of the maps:
To make the long story short, I need to compare and search values inside the outer_map's vlaue (inner_map) by String Array items, and then produce another String Array to add matched items.
If the String Array has there elements which are the same as one of the inner_map's random (for example; value2, value1, and value7) values, how can I search and compare these items to add to another String Array?
The latest code snippet I tried and I couldn't succeed:
if( !( theStringArray.equals("") ) )
{
while( outer_map.keySet().iterator().hasNext() )
{
for( int i=0; i <= theStringArray.length; i++)
{
// outer_map keys are order as 1,2,3,..,8
theStringArray[i] = outer_map.get(String.valueOf(i+1)).get("key1");
...
}
}
}
EDIT: Map generating function
private void parse(String in) throws IOException
{
reader = new JsonReader(new StringReader(in));
...
int nodeCounter = 1;
while(reader.hasNext())
{
...
String nameAsKey1 = "blabla"; // value1
inner_map.put("name", nameAsKey1);
String surnameAsKey2 = "blabla"; // value2
inner_map.put("surname", surnameAsKey2);
...
outer_map.put(String.valueOf(nodeCounter), (HashMap<String, String>) inner_map);
inner_map = new HashMap<String, String>();
nodeCounter++;
}
}
EDIT: I don't know how I can explain the issue more clearly, but may be this will help to understand about it: Map structure
I assume you have an array of String and a Map of map. Now you want to search the value fields of inner map against the array of String and if make a new string array with matching values.
If that is the case the below program will help you..
import java.util.HashMap;
import java.util.HashSet;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Set;
public class InnerMapSearch {
public static void main(String[] args) {
Map<String, HashMap<String, String>> outer_map = new HashMap<String, HashMap<String, String>>();
Map<String, String> inner_map = new HashMap<String, String>();
String[] searchParams = {"blabla1", "blabla3", "blabla20"};
//Populating the map
int reader = 1;
while (reader < 10) {
String nameAsKey1 = "blabla" + reader; // value1
inner_map.put("name", nameAsKey1);
String surnameAsKey2 = "blabla" + reader; // value2
inner_map.put("surname", surnameAsKey2);
outer_map.put(String.valueOf(reader), (HashMap<String, String>) inner_map);
inner_map = new HashMap<String, String>();
reader++;
}
//Searching
Set<String> searchResults = new HashSet<String>(); // Using set to avoid duplicate
// Iterate over the outer map
for(String key : outer_map.keySet()){
// Iterate through each inner_map value of outer map
for(Entry<String, String> innerEntry : outer_map.get(key).entrySet()){
// Iterate through the list of search params and see if its present in inner_hashmap
for(String searchParam : searchParams){
if(searchParam.equals(innerEntry.getValue())){
// The search parameter is in inner map so adding to result.
searchResults.add(searchParam);
}
}
}
}
// Converting the list to an array.
String[] searchResultsArray = searchResults.toArray(new String[searchResults.size()]);
}
}
Related
I set list on another class
List<DataModel> dataList = new ArrayList<DataModel>();
parsed on class
for(DataModel list : dataList) {
final String[] data = {list.getVar_a(), list.getVar_b()};
System.out.println("out data");
System.out.println(list.getVar_a());
System.out.println(list.getVar_b());
}
this prints data
out data
val_a
val_b
Model Class
class DataModel {
private String var_a, var_b;
//Getter & Setter
}
But now, I use and set map on another class and I'm not implementing a model class because in real case it has too many variables.
Map<String, Object> mapData = new LinkedHashMap<String, Object>();
when I set data on map, its result from database
Map<String, Object> map = new LinkedHashMap<String, Object>();
msg = (String) cs.getObject(5);
rs = (ResultSet) cs.getObject(4);
ResultSetMetaData rsmd = rs.getMetaData();
int count = rsmd.getColumnCount();
if(rs.next()){
int jml = 0;
do {
Map<String, Object> data = new LinkedHashMap<>();
for (int i = 1; i <= count; i++ ) {
String name = rsmd.getColumnName(i);
data.put(name, rs.getObject(name));
}
map.put(""+jml, data);
jml++;
} while(rs.next());
setStatus(SUCCESS);
setMessage(msg);
} else {
LOG.info(NO_DATA_FOUND);
}
parsed on class
for(Map.Entry<String,Object> list : mapData.entrySet()) {
String key = list.getKey();
Object val = list.getValue();
System.out.println("out data");
System.out.println(key);
System.out.println(val);
}
this prints data
out data
0
{var_a=val_a, var_b=val_b}
I want to get value on object like this
out data
val_a
val_b
Change your Map for loop to:
for(Map.Entry<String,Object> list : mapData.entrySet()) {
DataModel value = (DataModel) list.getValue();
System.out.println("out data");
System.out.println(value.getVar_a());
System.out.println(value.getVar_b());
}
First you have a map of object, and what you really need is a Map of Map.
Here is your reading a map of object.
for(Map.Entry<String,Object> list : mapData.entrySet()) {
String key = list.getKey();
Object val = list.getValue();
System.out.println("out data");
System.out.println(key);
System.out.println(val);
}
What you really need is a map of map as I am showing below.
Map<String, Map<String, Object>> map = new LinkedHashMap<String, Map<String, Object>>()
Now if you read it as map of map, You can have the result that you need.
0 : {a1:v1, a2:v2, etc...},
1 : {a2:v2, a2:v2, etc...},
2 : {a3:v3, a3:v3, etc...}
for(Map.Entry<String,Map<String, Object> list : mapData.entrySet()) {
String key = list.getKey();
System.out.println("out data");
for(Map.Entry<String,Object> innermap : list.getValue().entrySet()) {
//System.out.println(innermap.getKey());
System.out.println(innermap.getValue());
}
}
i have a question using a String with this format in Java(Android):
"{ key1 = value2, key2 = value2 }"
What's the best way to convert this String into Object?
I appreciate any help!
HashMap<String, String> getMap(String rawData) {
HashMap<String, String> map = new HashMap<>();
String[] pairs = rawData.split(","); // split into key-value pairs
for(String pair: pairs) {
pair = pair.trim(); // get rid of extraneous white-space
String[] components = pair.split("=");
String key = components[0].trim();
String value = components[1].trim();
map.put(key, value); // put the pair into the map
}
return map;
}
You can use it like this:
HashMap<String, String> map = getMap("key1 = value1, key2 = value2");
String valueForKey1 = map.get("key1"); // = value1
I have a query string like
"1_timestamp=201612312&1_user=123&2_timestamp=20145333&2_user=5432";
But I want to make them in array like below.
array(
0 => (
timestamp = 201612312,
user = 123,
),
1 => (
timestamp = 201612312,
user = 123,
),
);
I'm sorry to show you php type of array though I'm new to java.
How do I make it something like that?
Thank you
This is the closest structure to what you are doing in php, and if your data has more fields it can be easily added to the Data class:
import java.util.ArrayList;
import java.util.List;
class Data {
int timestamp;
int user;
Data(int ts, int user) {
this.timestamp = ts;
this.user = user;
}
}
public class Test {
public static void main(String[] args) {
List<Data> data = new ArrayList<Data>();
Data d1 = new Data(201612312, 123);
Data d2 = new Data(201612312, 123);
data.add(d1);
data.add(d2);
System.out.println(data.get(1).user);
}
}
You can do it without writing a class. You can use it like this.
Map<String, String> map1 = new HashMap<String, String>();
map1.put("1_timestamp", "201612312");
map1.put("1_user", "123");
Map<String, String> map2 = new HashMap<String, String>();
map2.put("2_timestamp", "20145333");
map2.put("2_user", "5432");
List<Map<String,String> mapList = new ArrayList<Map<String, String>>();
mapList.add(map1);
mapList.add(map2);
for (Map<String, String> map : list) {
for (Map.Entry<String, String> entry : map.entrySet()) {
System.out.println(entry.getKey() + " - " + entry.getValue());
}
}
Okay so I have spent several hours trying to wrap my head around this concept of a HashMap in Java but am just not able to figure it out. I have looked at many tutorials but none seem to address my exact requirement and I cannot get it to work.
I am trying to create an associative multi dimensional array in Java (or something similar) so that I can both save to and retrieve from the array with keys that are Strings.
This is how I would do it in PHP and explains it best what I am trying to do:
//loop one - assign the names
myArray['en']['name'] = "english name";
myArray['fr']['name'] = "french name";
myArray['es']['name'] = "spanish name";
//loop two - assign the description
myArray['en']['desc'] = "english description";
myArray['fr']['desc'] = "french description";
myArray['es']['desc'] = "spanish description";
//loop three - assign the keywords
myArray['en']['keys'] = "english keywords";
myArray['fr']['keys'] = "french keywords";
myArray['es']['keys'] = "spanish keywords";
//later on in the code be able to retrive any value similar to this
english_name = myArray['en']['name'];
french_name = myArray['fr']['name'];
spanish_name = myArray['es']['name'];
This is what I tried in Java but it is not working:
HashMap<String, HashMap<String, String>> myArray = new HashMap<String, HashMap<String, String>>();
myArray.put("en" , put("name", "english name")); //gives me "cannot find symbol" at second put
myArray.put("en" , ("name", "english name")); //gives me "')' expected" after second comma
So I am sure its something simple that I am missing but please point it out because this is very frustrating!
Thanks
EDIT:
So here is some working code on how I implemented the answer I accepted:
import java.util.*;
HashMap<String, HashMap<String, String>> finalArray = new HashMap<String, HashMap<String, String>>();
String[] langArray = {"en","fr","de","no","es"};
//Initialize each language key ahead of time
for(String lang : langArray) { // foreach lang in langArray
if (!finalArray.containsKey(lang)) {
finalArray.put(lang, new HashMap<String, String>());
}
}
//loop one - assign names
for(String lang : langArray) {
String theName = lang + " name"; //go get the name from somewhere
finalArray.get(lang).put("name", theName);
}
//loop two - assign description
for(String lang : langArray) {
String theDesc = lang + " description"; //go get the description from somewhere
finalArray.get(lang).put("desc", theDesc);
}
//loop three - assign keywords
for(String lang : langArray) {
String theKeys = lang + " keywords"; //go get the keywords from somewhere
finalArray.get(lang).put("keys", theKeys);
}
//display output
for(String lang : langArray) {
System.out.println("LANGUAGE: " + lang);
System.out.println(finalArray.get(lang).get("name"));
System.out.println(finalArray.get(lang).get("desc"));
System.out.println(finalArray.get(lang).get("keys"));
}
//example to retrieve/get values
String english_name = finalArray.get("en").get("name");
String french_desc = finalArray.get("fr").get("desc");
HashMap<String, HashMap<String, String>> myArray = new HashMap<String, HashMap<String, String>>();
if (!myArray.containsKey("en")) {
myArray.put("en", new HashMap<String, String>());
}
myArray.get("en").put("name", "english name");
In Java you have to be explicit about when you are creating an object. In this case first we check if there is already a HashMap object stored in our outer HashMap under the key "en". If not, we create an empty one.
Now to put a new value into it we have to first get it from the outer HashMap, then put the new value.
HashMap<String, HashMap<String, String>> myArray = new HashMap<String, HashMap<String, String>>();
HashMap<String, String> value = new HashMap<String, String>();
value.put("name", "English name");
value.put("desc", "English description");
value.put("keys", "English keywords");
myArray.put("en" , value);
value = new HashMap<String, String>();
value.put("name", "French name");
value.put("desc", "French description");
value.put("keys", "French keywords");
myArray.put("fr" , value);
Unfortunately, there's no concise syntax for constructing populated maps in Java. You'll have to write it out long-hand. A separate helper method can make it a little simpler:
HashMap<String, String> makeMap(String name, String desc, String keys) {
HashMap<String, String> map = new HashMap<>();
// Before Java 7, above must be: new HashMap<String, String>();
map.put("name", name);
map.put("desc", desc);
map.put("keys", keys);
}
Then:
HashMap<String, HashMap<String, String>> myArray = new HashMap<>();
myArray.put("en",
makeMap("english name", "english description", "english keywords"));
// etc.
You would retrieve it with:
english_name = myArray.get("en").get("name");
import java.util.HashMap;
public class Main
{
public static void main(String[] args) {
// Creating array
HashMap<String, HashMap<String, String>> myArray = new HashMap<String, HashMap<String, String>>();
// Setting values
for(int i=0; i<100;i++) {
myArray.put("key1"+i, new HashMap<String, String>());
myArray.get("key1"+i).put("key2"+i, "value"+i);
}
// Getting values
for(int i=0; i<100; i++) {
System.out.println(myArray.get("key1"+i).get("key2"+i));
}
}
}
I really liked the example by "dAv dEv", though he didn't really fill his double array of keys (I added a loop within a loop). I also like TreeMaps better than HashMaps because they aren't as random.
import java.util.Map;
import java.util.TreeMap;
TreeMap<String, TreeMap<String, String>> myArray =
new TreeMap<String, TreeMap<String, String>>();
String[] roles = { "Help Desk", "Administrator", "Super Use", ... };
String[] elements = { "Hydrogen", "Helium", "Lithium", "Beryllium", ... };
// Setting values TODO: read data values from Excel spreadsheet (or wherever)
for(String role : roles) {
myArray.put(role, new TreeMap<String, String>());
for (String elementName : elements) {
String value = Utils.getHumanName("first", true);
myArray.get(role).put(elementName, value);
}
}
// Getting values
for (Map.Entry<String,TreeMap<String,String>> entry1 : myArray.entrySet()) {
String key1 = entry1.getKey();
TreeMap<String,String> value1 = entry1.getValue();
for (Map.Entry<String,String> entry2 : value1.entrySet()) {
String key2 = entry2.getKey();
String value2 = entry2.getValue();
System.out.println("(" + key1 + ", " + key2 + ") = " +
myArray.get(key1).get(key2));
}
}
P.S. I used Utils.getHumanName() as my data generator. You will need to use your own.
String format is (not json format)：
a="0PN5J17HBGZHT7JJ3X82", b="frJIUN8DYpKDtOLCwo/yzg="
I want convert this string to a HashMap:
key a with value 0PN5J17HBGZHT7JJ3X82
key b with value frJIUN8DYpKDtOLCwo/yzg=
Is there a convenient way? Thanks
What I've tried:
Map<String, String> map = new HashMap<String, String>();
String s = "a=\"00PN5J17HBGZHT7JJ3X82\",b=\"frJIUN8DYpKDtOLCwo/yzg=\"";
String []tmp = StringUtils.split(s,',');
for (String v : tmp) {
String[] t = StringUtils.split(v,'=');
map.put(t[0], t[1]);
}
I get this result:
key a with value "0PN5J17HBGZHT7JJ3X82"
key b with value "frJIUN8DYpKDtOLCwo/yzg
for key a, the start and end double quotation marks(") is unwanted; for key b, the start double quotation marks(") is unwanted and the last equals sign(=) is missing.
Sorry for my poor english.
Probably you don't care that it's a HashMap, just a Map, so this will do it, since Properties implements Map:
import java.io.StringReader;
import java.util.*;
public class Strings {
public static void main(String[] args) throws Exception {
String input = "a=\"0PN5J17HBGZHT7JJ3X82\", b=\"frJIUN8DYpKDtOLCwo/yzg=\"";
String propertiesFormat = input.replaceAll(",", "\n");
Properties properties = new Properties();
properties.load(new StringReader(propertiesFormat));
System.out.println(properties);
}
}
Output:
{b="frJIUN8DYpKDtOLCwo/yzg=", a="0PN5J17HBGZHT7JJ3X82"}
If you absolutely need a HashMap, you can construct one with the Properties object as input: new HashMap(properties).
Added few changes in Ryan's code
public static void main(String[] args) throws Exception {
String input = "a=\"0PN5J17HBGZHT7JJ3X82\", b=\"frJIUN8DYpKDtOLCwo/yzg=\"";
input=input.replaceAll("\"", "");
String propertiesFormat = input.replaceAll(",", "\n");
Properties properties = new Properties();
properties.load(new StringReader(propertiesFormat));
Set<Entry<Object, Object>> entrySet = properties.entrySet();
HashMap<String,String > map = new HashMap<String, String>();
for (Iterator<Entry<Object, Object>> it = entrySet.iterator(); it.hasNext();) {
Entry<Object,Object> entry = it.next();
map.put((String)entry.getKey(), (String)entry.getValue());
}
System.out.println(map);
}
Split the String on the Basis of commas (",") and then with with ("=")
String s = "Comma Separated String";
HashMap<String, String> map = new HashMap<String, String>();
String[] arr = s.split(",");
String[] arStr = arr.split("=");
map.put(arr[0], arr[1]);
You can also use the regex as below.
Map<String,String> data = new HashMap<String,String>();
Pattern p = Pattern.compile("[\\{\\}\\=\\, ]++");
String[] split = p.split(text);
for ( int i=0; i+2 <= split.length; i+=2 ){
data.put( split[i], split[i+1] );
}
return data;