Java how to store data

How do I store this data in Java?

To add them to your dictionary, you can first verify if your id has already been read (using the method)- in which case you just append the word to the list corresponding to that id — or, if this is not the case, you create a new list with this word: Then whenever you want to retrieve your list of strings for a certain id you can simply use dictionary.get(id); You can find more information on HashMaps on the Java documentation Question: Since hashing is required where value needs to be retrieved from a large set of data. Question: I am trying to one user id and store multiple values like firstname , lastname, city etc. but at same time again store same user id and same value gate so how to store only one time not store duplicate record any one please help me and give me more details please friend .

How do I store this data in Java?

I want a dictionary of values. The keys are all strings. Each key corresponds with some sort of list of strings. How do I make a list of strings for each key and update that accordingly? I’ll explain:

I have a loop that is reading lines of a word list. The words are then converted into a string code and set as keys in the dictionary. Here is an example of the string code/word relationship.

However, my program keeps looping through the word list and eventually will run into a word with the same code as «the», but maybe a different word, lets say «cat». So I want the list to look like:

How do I get it to make an arraylist for every key that I can then add to on the fly when needed? My end goal is to be able to print out the list of words in that list for a called code (.get())

You can make a HashMap . In your case HashMap> works fine.

Like it has already been said, a MultiMap seems to be what you need. Guava that was already suggested and it’s a good option. There is also and implementation from commons-collections you can use.

From commons-collections documentation:

 MultiValuedMap map = new MultiValuedHashMap(); map.put(key, "A"); map.put(key, "B"); map.put(key, "C"); Collection coll = map.get(key); // returns ["A", "B", "C"] 

You can always implement your own MultiMap if you don’t want to use an external library. Use a HashMap> to store your values and wrap it with your own put, get and whatever other methods you see fit.

It sounds like you want a Multimap from the Guava library.

You can also go the route of using a Map> , but then you will need to manually handle the case where the list is null (probably just allocate a new list in that case).

You can use a HashMap that links each id to a list of strings:

Map> dictionary = new HashMap>(); 

Now let’s say you read two Strings: id and word . To add them to your dictionary, you can first verify if your id has already been read (using the containsKey() method)- in which case you just append the word to the list corresponding to that id — or, if this is not the case, you create a new list with this word:

//If the list already exists. if(dictionary.containsKey(id)) < Listappended = dictionary.get(id); appended.add(word); //We add a new word to our current list dictionary.remove(id); //We update the map by first removing the old list dictionary.put(id, appended); //and then appending the new one > else < //Otherwise we create a new list for that id ListnewList = new ArrayList(); newList.add(word); dictionary.put(id, newList); > 

Then whenever you want to retrieve your list of strings for a certain id you can simply use dictionary.get(id);

You can find more information on HashMaps on the Java documentation

Collections — How do I create a dictionary in java similar to the python, The result is an immutable Map> , unlike Python, where the result is mutable. Printed, it looks like this, where order

Implementing Dictionaries using the Map Interface in Java

105 Java — The Dictionary Class

What is the best way to keep key,value pair in java collection apart from Hashmap?

Since hashing is required where value needs to be retrieved from a large set of data. But sometimes this is also possible that we need such collection that can store key, value pair for minimal data.

Just take a look at the interface Map in the documentation. There you can find other implementations of key-value stores:

All Known Implementing Classes: abstractmap, Attributes, AuthProvider, ConcurrentHashMap, concurrentskiplistmap, EnumMap, HashMap, Hashtable, Headers, IdentityHashMap, LinkedHashMap, PrinterStateReasons, Properties, Provider, RenderingHints, ScriptObjectMirror, SimpleBindings, TabularDataSupport, TreeMap, UIDefaults, WeakHashMap

105 Java — The Dictionary Class, How to use Dictionary Class in Java? how to code java RedSysTech Java scjp Duration: 9:04

One key but multiple values store using java collection?

I am trying to one user id and store multiple values like firstname , lastname, city etc. but at same time again store same user id and same value gate so how to store only one time not store duplicate record any one please help me and give me more details please friend .

you can create a JAVA bean class that consists of all the required data. like :

then you can store that bean against a userId in a collection Map . like :

Map map=new HashMap<>(); map.put("12345",new Data()); 

You should have some Map object something like

then add the user as follows:

 if(null == myMap.get(userId)) myMap.put(userId, custObj); 

Your custom object would be like

 public class CustomObject < private String fname; private String sname; // more fields and getter setters >

Now you can save User with id like this —

user1 = new User(id, firstName, lastName, city . ) userMap.put(1, user1); user2 = new User(id, firstName, lastName, city . ) userMap.put(2, user2); 

How to convert a list collection into a dictionary in Java?, Dictionary; import java.util.Hashtable; public class CollectionDictionary < public static void main(String[] args) < ArrayListlist

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How to store data in objects java

Then change with I hope this is what you meant Edit : Or continue using constructors and do validaing with parameters BEFORE you make new instance of Student Solution 2: It’s not so clear but actually what you want to do is to inizialize a student without adding it to the array until you are sure that fields are correct This approach will keep asking the user the same field until it’s correct.. of course your setters will need to return a boolean that is if validation failed. Solution: You can either use the methods provided to populate the fields of the object one at a time, so if you have an object named employee, that takes in 3 arguments (id, name and salary), you can have something like this: Or else, you can use an ORM Tools, like Hibernate and use it to retrieve objects as shown here P.S.

How to store the data in a object array, which collected from data base?

You can either use the get methods provided to populate the fields of the object one at a time, so if you have an object named employee, that takes in 3 arguments (id, name and salary), you can have something like this:

List employee = new ArrayList(); while(rs.next())

Or else, you can use an ORM Tools, like Hibernate and use it to retrieve objects as shown here

P.S. The Java code I have provided is more like Pseudo code. I have not tested it.

Load/Store Objects in file in Java, The solution of this problem is that when you are using other objects, let say class A, into a collection like HashMap and want to serialize the HashMap object, then implement the interface Serializable for class A like this: class A implements Serializable < >HashMap hmap; Otherwise …

Java : Storing Data in Array Of Object from JOptionPane Dialog

Don’t use values as constructor parameters.

Use only implicit constructor that will allocate memory. As for set methods, write them like :

public void setName(String name)

In this set methods do your validation code . Your class needs to have private attiributes, which are exact same as your constructor parameters.

Then change line s[i]=new student(i,name,major,gpa); with

s[i] = new Student(); s[i].setNumber(i); s[i].setName(name); s[i].setMajor(major); s[i].setGpa(gpa); 

I hope this is what you meant

Edit : Or continue using constructors and do validaing with parameters BEFORE you make new instance of Student

It’s not so clear but actually what you want to do is to inizialize a student without adding it to the array until you are sure that fields are correct

Student[] s = new Student[5]; String name, major; double gpa; boolean isCorrect = false; Student currentStudent; // in your code there is i = 1, is it intended or mistake? for (int i=0; i isCorrect = false; while (!isCorrect) < major = JOptionPane.showInputDialog("Please Write Major for student n " + i); isCorrect = currentStudent.setMajor(major); if (!isCorrect) JOptionPane.showMessageDialog(null, "Errors in validating major!"); >isCorrect = false while (!isCorrect) < gpa = Double.parseDouble(JOptionPane.showInputDialog("Please Write GPA for student n " +i)); isCorrect = currentStudent.setGPA(gpa); if (!isCorrect) JOptionPane.showMessageDialog(null, "Errors in validating GPA!"); >s[i] = currentStudent; > 

This approach will keep asking the user the same field until it’s correct.. of course your setters will need to return a boolean that is false if validation failed.

Working with JSON Data in Java, JSON Object Encoding in Java: As we discussed above, this json.simple library is used to read/write or encode/decode JSON objects in Java. So let’s see how we can code for encoding part of the JSON object using JSONObject function. Now we create a java file mainEncoding.java and save …

What array to use to store an Object?

This line of steps maybe helpful to you..

In case of Array you can store only one kind of data,

Object[] myObjectArray = Object[NumberOfObjects]; myObjectArray[0] = new Object(); 

If you are talking about the String object, then you can store your String object also.

String[] myStringArray = String[NumberOfObjects]; myStringArray[0] = new String(); or String[] myStringArray = String[NumberOfObjects]; myStringArray[0] = "Your String"; 

Here you can store your string object of Sting without using new operator.

Assuming, you have something like this

the you can store an instance of that class in an array:

MyClass[] myClasses = ; System.out.println(myClasses[0].one); // will print "one" 

There are some different ways to create an array (of Strings) and to set values:

String[] strings = new String[3]; strings[0] = "one"; strings[1] = "two"; strings[2] = "three"; 

String[] strings = new String[]; 

Better way to use List, it is a collection interface. we are not storing objects , we are storing references(Memory addresses) of the objects. and use generics concept give more performance.

 Ex: List references = new ArrayList(); List references = new ArrayList(); 

Storing objects in a database java, Sorted by: 3. You need to override the toString method. public String toString () < StringBuilder sb = new StringBuilder (); sb.append ("Name: "); sb.append (this.name); //rest of fields return sb.toString (); >As a matter of clarity, you are not returning its location in the database. You are getting back the object …

How to store Objects from Database?

You can implement the Comparator interface and use Collections.sort() , a modified mergesort, as shown here.

Maybe you already did that but it’s not so clear in your question:

You can get almost as many instances of your data class (Ideas) but it’s not the same at all with graphic classes. Limit the number of widgets and graphics to 1.

Build your own custom JPanel class, give it a list of Ideas and override the paintComponent method to draw all items in the list.

If your visible area is large, double buffer it.

I disagree with that and not good idea to holding lots of data in local Memory, with idea to simulate, excelent optimalized preprocesor from Sql Engine (most of todays engines), then basically faster as best EndUser PC

and if you have some WHATEVER permisions to the Database, then there are still exist option(s) to loading data from DbEngine to the Embedded database (on Memory), maybe to H2 or maybe JavaDB

How Objects Can an ArrayList Hold in Java?, Data-type of the elements that are to be stored in the ArrayList is either String or Integer type. Second half: Making the same ArrayList with class objects as elements. Syntax: Declaring List. ArrayList names = new ArrayList (); Here represents the data-type of the elements …

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