Suppose i have a hashMap which includes instances of class Employees and instances of class Customers.
How can i get the employees objects only?
And would it be possible to find the oldest staff by comparing the ages stored in the age fields of the staff objects.
I have a requirement to find the greatest/maximum of the given list of Calendar objects in Java.
i.e., 2013/01/26
2014/03/03
2012/02/27
2014/01/15
So the above list of calendar objects are in Arraylist. I need to get the max/greatest among these. Eventually, the answer should be 2014/03/03
I am currently working on a project where I need to return data from a database over RMI to a client who requests it. Some of the fields in the Data Object can not be seen by the client so I need to create another object to send over the network instead. The method I use is this...
public static SerializableObject createSerializableObjectFromDataObject(DataObject dataObject){
SerializableObject serializableObject = new SerializableObject();
serializableObject.setField(dataObject.getField());
serializableObject.setAnotherField(dataObject.getAnotherField());
return serializableObject;
}
Is there a better way of doing this? I am creating many subclasses DataObject which all require this static method to be implemented and I can't push it into the superclass because each one needs custom behaviour.
In my code I read in a file of states and statecapitals then store them into a hashmap. I then ask the user what the capital is for the random state displayed.The problem I am having is getting the value for the random generated state. When I enter the correct capital for the state, it is still being marked incorrect. Here is my code.
Java Code: try {
Scanner scanner = new Scanner(file);
String[] values;
[code]....
I have two Hasmaps as
Map<String,String> componentValueMap = new HashMap<String,String>();
Map<String,Map<String,String>> componentNameValueMap = new HashMap<String,Map<String,String>>();
I have for loop which are getting values from XML
XML structure as
<Raj>
<user>raj</user>
<password>123</password>
</Raj>
<Dazy>
<user>dazy</user>
<password>123</password>
</Dazy>
Now during first loop it will put user and password in map and after that put map refernce in another map. Same procedure for another values. But during iterating componentNameValueMap , i am getting Raj, Dazy as Key but not getting different values for them. I am getting latest values of Dazy in both Keys.
Because put method of Map<String,String> componentValueMap is replacing values. But I don't to replace them and want to get different values for different keys.
I am trying to retrieve a object from a hashMap not I am not sure what is wrong. I am trying to calculate if a car was speeding. They're 5 cameras and as they pass each camera I can calculate the speed. They key is camera number and I am sending in a Vehicle object.
Now I am trying to retrieve variables from the Vehicle so I can do the calculations. I am getting the error in the loop in void calculateSpeeding(). The loop is only for testing at the moment.
package online.practice.averageSpeed;
import java.util.Arrays;
import java.util.HashMap;
public class Vehicle {
String licensePlates;
[Code] ....
I have a hashmap of the form HashMap <String, Set<String>>I am trying to create a method with one argument. The argument is a key for the hashmap, if it exists it should print out the key and the associated values. I'm falling over at even getting it to print the key, it keeps printing all the keys from within the hashmap as I don't know how to load the argument into it. I have this so far
Java Code:
public void printValue(String club)
{
boolean result = clubMap.containsKey(club);
if (result)
{
String key = clubMap.keySet(club).toString();
System.out.println(key );
[code]....
I am asked in my assignment to make a program that accepts a text file as an example a novel and i have to sort each word as a PERSON or ORGANIZATION or LOCATION or O as in Other , example :
Microsoft/ORGANIZATION ,/O Nelly/PERSON !/O '/O
Now we notice that microsoft is and organitzation and "," is Other and Nelly is a person's name and so on ..
Now I am asked to return the numbers of tags in the text which is 4 in our case because we have (ORGANIZATION,PERSON,LOCATION,OTHER)
My question here is my logic true ? And since i made a map of String,String ; Is there any way that i can get the size of the values in our case the values are the organization etc.. ?
import java.io.File;
import java.io.FileNotFoundException;
import java.util.Collection;
import java.util.Collections;
import java.util.HashMap;
[code].....
I have one doubt.In HashMap if keys contains 1,2,3,4 and values are a,b,c,d we can get values using get(key) method like 1 will A,2 will return B and so on. Can we get the keys from values like A will get 1 and also if in key if there is a String like 1,2,3,Z and value is A,B,C,7 Z should get me 7. Here I am not using any generics.
View Replies View RelatedHow get method of HashMap or Hashtable works internally in Java can any body let me know how does it work..
View Replies View RelatedI have a pretty large Hashmap (~250MB). Creating it takes about 50-55 seconds, so I decided to serialize it and save it to a file. Reading from the file takes about 16-17 seconds now.
The only problem is that lookups seems to be slower this way. I always thought that the hashmap is read from the file into the memory, so the performance should be the same compared to the case when I create the hashmap myself, right? Here is the code I am using to read the hashmap into a file:
File file = new File("omaha.ser");
FileInputStream f = new FileInputStream(file);
ObjectInputStream s = new ObjectInputStream(new BufferedInputStream(f));
omahaMap = (HashMap<Long, Integer>) s.readObject();
s.close();
300 million lookups take about 3.1 seconds when I create the hashmap myself, and about 8.5 seconds when I read the hashmap from file.
SO my current code creates a graph with vertices and weighted edges. This data is stored in a hashmap. The key of the hashmap is the vertex and the value is a second hashmap. This second hashmap contains the edges with the vertex it connected to as the key and the weight as the value. My current problem is that when i try to remove vertices they are removed from the key set but they stay in the value(the second hashmap) as the key for that hashmap. IS THERE A WAY TO REMOVE THE VERTEX FROM THE KEYSET OF THE SECOND HASHMAP.
Code is as follows
constructor{
adjacencyMap = new HashMap<V, HashMap<V, Integer>>();
dataMap = new HashSet<V>();
}
removal method{
if(dataMap.contains(vertex)){
[Code]...
my project flow is html,css,js<--->ajax<-->jsp<--->jdbc(.java)<--->mysql. In that jdbc i am returning the records from the database and fill into the resultset. From the resultset i put all records in arraylist and passed to jsp then i am displaying data in the screen.Whether i can use arraylist, hashmap or treetable?
View Replies View RelatedI have a a hashmap in request attribute which is available to jsp file where i have a dropdown. Hashmap kay= value of this dropdown. As and when I select CLT i want to perform some opertation depending on value associated with that key in hashmap.
View Replies View RelatedI have a HashMap returned from the server. There are two conditions
1. HashMap returned with only one set of key value pair or
2. HashMap with multiple set of data key value pairs.
Now in UI I have to display either text box or drop down box depending upon the size of map for that I am using length method
Java Code:
<c:choose>
<c:when test="${fn:length(myDto.mayMapInDto) eq 1}">
display text box
</c:when>
<c:otherwise>
display drop box
</c:otherwise>
</c:choose> mh_sh_highlight_all('java');
I can display drop box by looping but not sure how I can get only one element for text box. Tricky is I can't use key value to access since UI don't know what key will be returned.
So I just want to store a Key in a HashMap which can related to two values. For example, the Key "ABC" related to "Fire" which in turn relates to "Heat".
How can I code this in a HashMap?
I am a C# developer but need to do some java development. The code produces the following error.
import java.util.ArrayList;
import java.util.Collection;
import java.util.HashMap;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;
...
HashMap<String, String > myMap = new HashMap<String, String>(){{
put("a","b");
}};
myMap.put("foo", "bar");
myMap.put("Sna", "foo");
...
Generates this error
C:/FSC/apache-tomcat-6.0.41/webapps/aspen/temp/x2_8656248460570782763/x2_5214718769032742331/StudentExport.java:47: error: <identifier> expected
myMap.put("foo", "bar");
^
What am I missing?
My perfect idea is to have a Hashmap that would increase size each Key & value added, it's almost like a self-increasing array. I mean I could just create a very large Hashmap for me to add objects to anytime I want with a key to be able to find the object. Is this the most efficient way, because I'm trying to make my Object Library compatible with any amount of Objects, however, I know there's a limit to how many values you can have in an array, but it's larger than I'll ever need.
Let's say I'm making a number storage program, and I may need from 3 to 8 numbers to be stored with a key to find them easily using a Hashmap, rarely I may need below 3 or above 8. So is it efficient for me to create a Hashmap that has 10 placeholders? Or can I make this more efficient. Note, my Library is static.
I want to write a method to print the all the names of a phone book. phoneBook is a HashMap<String, String> , that has names as keys and phone numbers as values.
Reading the documentation for both HashMap and Set, I have more or less an idea of how it could be done but I cant put it on code..
public String getName()
{
String[] keys = phoneBook.keySet().toArray();
return keys[0];
}
This is wrong. It doesnt compile saying incompatible types. I was thinking first to manage to succeed to get a key from my phone book and then I change it to print all the keys.
I have some paired values stored as a hashmap in my model, for example sake, we'll say the 'key' is a Manager's ID and the 'value' is the name of their department, so 'betty123' could be a key to a value 'IT', and 'dave345' could be a key for the value 'Finance'. This hashmap is populated from a database. In my form, I have two "Select" dropdown fields, one for "Department" (with fields which match the values in the hashmap), and one for "Manager ID". I want to autopopulate the "Manager ID" field when the "Department" field is changed, based on the values in the Hashmap. I understand that I can't access dynamically elements of the hashmap in a script, so, for example, I can't do this:
var specificDepartment= $("#department");
var managerId = ${departmentHash[specificDepartment]};
$("#manager").val(managerId);
Because this code is dynamic based on the value of "department" at the time it's run, whereas the departmentHash object is generated when the page is loaded.
Is there some other way I can do this? Am I approaching it the wrong way? FWIW, I'm using Spring 4.1.1 and jQuery 1.8. I understand the conceptual block with code I wrote above, but I can't for the life of me think of an obvious solution although I'm sure this is a fairly commonplace problem in web development.
my query is like: "i want to create hashmaps where the inner hashmap contains the key as firstname and value as a Class Student which contains parameters firstname, lastname,etc. I need this hashmap to be accessed by other objects of different classes".
public class Student {
private String FirstName;
private String LastName;
private String EmailAddress;
private String PhoneNumber;
private String Username;
private String Password;
private String EducationalInstitution;
[code]....
As we give the values by Scanner, it should be Stored in Hashmap and how those values can be accessed by other object classes?How does the Logic works? What my next step?
What are the difference between hashmap, linkedlist and arraylist ... when they are used and why?
View Replies View RelatedI have the following hashMap declared:
private HashMap<String, Car> cars = new HashMap<String, Car>();
How can i get an array of String filled with hashMap keys?
I have a file called statecapitals.txt that is read in, I want to store it in either a 2d array or hashmap and select a random state then Ask the user for the name of the capital. Then I want to Let them know if they are correct or not and have a choice to play as many times as they like. When they no longer want to play,I want to let them know how many they got correct and how many incorrect. I am not sure which would be better a hash map or 2d array and dont know where to start with each.
here is what the text file looks like:
Alabama - Montgomery
Alaska - Juneau
Arizona - Phoenix
Arkansas - Little Rock
California - Sacramento
Colorado - Denver
[code]....
Which two method HashMap key object should implement?..
View Replies View RelatedI have a 2D array and the elements are listed as follows:
outlook temperature humidity windy gooutside
sunny hot high false n
overcast hot high false y
....
I need to put these values into a HashMap, where the elements of the first row are the keys and the elements from row 1 to n-1 are the values. What would be the best way to make sure the key and values are matched correctly?
Here is what I have:
String[][] array = new String[numberOfRows][numberOfCols];
HashMap<String, String> map = new HashMap<String, String>();
for(int rows = 0; rows < (numberOfRows * numberOfCols); rows++) {
for(int cols = 0; cols < array[i].length; cols++} {
map.put(array[0][cols], array[rows*cols][col];
}
}
I keep getting the out of bounds error.