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 RepliesHere is my HashMap and a method for listing all the keys in it
HashMap<String, String> exampleOne = new HashMap<String, String>();
public void allKeys() {
int i;
i =0;
for (String name: exampleOne.keySet())
[Code]....
Now I want to return all values that associated with one key. How do I do this? Or is it possible to other way round? I mean return All keys associated with a value?
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 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 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?
My objective here is to process a HashMap's key's in order. I found SortedSet as a way to do it.
The HashMap is like this:
nobelPrizeWinners = new HashMap<String, PrizeWinner[]>();
// 2009:
nobelPrizeWinners.put(new String ("2009 Physics"), new PrizeWinner[] {new PrizeWinner("Charles K.", "Kao"), new PrizeWinner("Willard S.", "Boyle"), new PrizeWinner("George S.", "Smith")});
[Code] ....
This is the method I am trying to write
public void displayAllYearsAndWinners_2()
{
// Creation of the SortedSet
SortedSet sortedSet = new TreeSet();
[Code] ....
However, the compiler gives me a warning of NobelPrizeWinners.java uses unchecked or unsafe operations. Recompile with -Xlint:unchecked for details.
As I said, my objective here is to process them in order. If this compiler warning cannot be resolved, I am open to other methods of accomplishing my objective.
I'm learning Java using BlueJ, I have made a class that has a HashMap of (String, String) that contains an the make of a car and the model.
I want a method to return a collection of all the keys that satisfy a condition, like if someone wants to find what make a certain model is. I know it requires a loop, just not too sure how to write the loop to satisfy the condition.
I 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.
Currently working on a simple file processing problem, namely, reorder a set of strings (called bid phrases) in terms of the score value associated to them in descending order.
My code outputs everything in ASCENDING order.
How to twist HashMap values around?
import java.io.BufferedReader;
import java.io.FileReader;
import java.io.FileWriter;
[Code].....
I am working on the Kevin Bacon - 6 degrees of bacon problem. I want to take my Array List and use the index and Values that I have saved in it as the Key and Value of a Hashmap. Below is my code.
HashMap<Integer, ArrayList<String>> actors =
new HashMap<Integer, ArrayList<String>>();
ArrayList array = new ArrayList();
try (BufferedReader br = new BufferedReader(
new FileReader("actors.txt"));)
[code]...
saving each one in it's own spot. I want to use the index of each one as the key to find it in the Hashmap....
I need assigning the selected hashmap values into a list and to display the values in a jsf page. The user will select certificates and will be stored in the below list:
private List<String> selectedCertificates = new ArrayList<String>();
The selectedCertificates will have the values ("AA","BB"). Now I will be passing the list into a hashmap in order to get the names and to display them on the jsf page.
My code is below:
Map<String, String> CertificatesNames =
new HashMap<String,String>(selectedCertificates.size());
CertificatesNames.put("AA", "Certificate A");
CertificatesNames.put("BB", "Certificate B");
CertificatesNames.put("CC", "Certificate C");
for(String key1: selectedCertificates) {
System.out.println(CertificatesNames.get(key1));
}
I want to display in my jsf page :
Certificate A
Certificate B
Now my issue is that is how to display all the values of the CertificatesNames.get(key1) in the jsf page as I tried to do the below and it printed all the values when I used the #{mybean.beans} using the :
List beans =
new ArrayList(CertificatesNames.values());
So how to do this?
I am writing a code that tries to figure out the users password by going through every possible key (brute force). Although I think its going to work, it looks EXTREMELY inefficient to me, since its just a huge switch statement for each character -- 94 total, including the shift values. Is there a built in method in the JAVA API that goes through every key or something?
Here is my code for that segment:
public char[] HackingPassword(){
char[] passChars = this.password.toCharArray();//convert the password to char[]
char[] hacking = new char[passChars.length];//make the hacking variable same size as users password
int nextCharValue = 0;//this is used to cycle through the keyboard
//check each letter of hacking to match with password
for(int i = 0; i < passChars.length; i++){
[Code] .....
I am new with java, eclipse, jpa(eclipselink), postgresql, and trying to make a web application. I have two tables:
bids: id, quantity, price
trades: bidid, askid, quantity, price
bidid and askid columns are foreign keys from bids table (id), and they are the primary key for the trades table.
I created the Entities from the Tables (Bid and Trade class) with eclipse and it generated a TradePK class for the primary key.
Trade.java:
@Entity
@Table(name="trades")
public class Trade implements Serializable {
@EmbeddedId
private TradePK id;
[Code] ....
I understand that this is necessary because the primary key is from two column, but as soon I want to persist a Trade back to the database Eclipselink call the column names twice:
INSERT INTO trades (price, quantity, datetime, BIDID, ASKID, bidid, askid) VALUES (?, ?, ?, ?, ?, ?, ?)
So postgres give me back an exception: ERROR: column "bidid" specified more than once
And I don't know why. According to the JPA docs I didn't found any mistake:
Introduction to EclipseLink JPA (ELUG) - Eclipsepedia
Or I just can't see it... or is there a better doc which explains it better?
I am trying to work with a SQL database and some JSF pages that were created with/for CRUD. The data comes up just fine but all my foreign keys show the primary key for the key not the data. So instead of having the actual Zone I get the number (my primary key) that matches the Zone.
example:
4717A Cool ReceptionTitle: Gatherer of Cool Companycom.vancowboy.lotor_db.LotroZones[ id=11 ]
The last item should read "All" not "com.vancowboy.lotor_db.LotroZones[ id=11 ]"
This was straight from a tutorial so I can learn this but the FK has got me baffled...
I Want to identify up, down, left and right keys with the keylistener() WHATE NAME DO I IDENTIFY IT WITH
View Replies View RelatedI am developing a java code using netbeans for encryption decryption by RSA algorithm. Swings and file handling play a major role in these code. My encryption code is working nicely but the code for decryption is not since keys file is not being read. That is why variable mod and pri are getting null values and the following error stack is coming. I know where the problem is somewhere in void readkeys() function but cannot solve it.
Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
at java.math.BigInteger.modPow(BigInteger.java:1579)
at rsakeydecryption1.RsaKeyDecryption.decryption(RsaKeyDecryption1.java:167)
at rsakeydecryption1.RsaKeyDecryption.read_output(RsaKeyDecryption1.java:294)
at rsakeydecryption1.RsaKeyDecryption.actionPerformed(RsaKeyDecryption1.java:330)
[Code] .....
My code for decryption is
package rsakeydecryption1;
import java.math.BigInteger;
import java.util.Random;
import java.io.*;
import javax.swing.*;
[Code] ....
Suppose that a certain BST has keys that are integers between 1 and 10, and we search for 5. Which sequence below cannot be the sequence of keys examined?
(a) 10,9,8,7,6,5
(b) 4,10, 8, 6, 5
(c)1,10,2,9,3,8,4,7,6,5
(d) 2,7,3,8,4,5
(e)1,2,10,4,8,5
I've noticed many differences, such as there is only one with an odd number of keys, and one has all integers from 1-10 inside of it, but I can't find any real reason that you wouldn't be able to search it?
I've started creating a simple game in Java, so now I'm stuck. I wanted to make moving character by fast alternating arrow keys, but I don't know how. I can make a boolean variable, which disables moving by pressing the same key again, but the player can just hold the key and character is still moving. I thought about changing position of character when the key is pressed, instead of increasing speed, but then the movement wouldn't be smooth. I think this may sound incomprehensible, so I will add a link to game like an example of what I mean.
Play Mini Sports Challenge game online - Y8.COM
I need to get a clone of a fairly deep object tree. All objects are entities and I need to set the primary keys to null. The root object:
public class Grundentscheidung implements Cloneable {
@OneToMany(cascade = CascadeType.ALL)
@JoinColumns({
@JoinColumn(name = "gesamtentscheidung_dstNr"),
@JoinColumn(name = "gesamtentscheidung_id")
[Code] .....
When I call
Grundentscheidung grundentscheidungClone = grundentscheidung.clone();
grundentscheidungClone contains the whole object tree with all dependencies, but the Tatbestand objects have their primary keys. When I use the debugger I see that Tatbestand.clone() is never called.
Is my code faulty? I would like to avoid to write a large method which sets all primary keys on the object tree to null.
I've visited this great site been following this java tutorial on making the snake game, and as I followed along at added the second player. Right up to the point I got into the resetting if I hit borders or myself or the other player, the snakes stopped moving when i tried hitting keys...problem started up to the point where I added snake2 in the GenerateDefaultSnake method
import java.awt.*;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import java.util.LinkedList;
import java.util.Random;
[code]....
I'm working on a Java 2D game which requires a max of six keys be held down at the same time.
The game is for two players on the same keyboard, playing simultaneously.
However, all three computers I ran the program on only allow a max of three keys held at a time. They all have trouble with reacting to more than three keys being held.
It seems that pressing a new key after three are already held, either cancels some other key-holding or is ignored.
I've been told that this is a hardware issue. Most keyboards can't handle more than three keys held at a time. But a lot of games do require this, and they do not require special gaming-keyboards to run on my computer without problems.
So there has to be a solution that will make the game playable on any standard keyboard.
(I use Key Bindings).
The game's controls:
Player 1
- Rotate sprite and set angle of movement: LEFT arrow
- Rotate sprite and set angle of movement: RIGHT arrow
- Move forward: UP arrow
- Shoot missile: ENTER key
Player 2
- Rotate sprite and set angle of movement: 'A' key
- Rotate sprite and set angle of movement: 'D' key
- Move forward: 'W' key
- Shoot missile: 'T' key
Relevant code:
The Key Bindings part:
Java Code:
// An action for every key-press.
// Each action sets a flag indicating the key is pressed.
leftAction = new AbstractAction(){
public void actionPerformed(ActionEvent e){
keysPressed1[0] = true;
[Code] .....
This is mostly how reacting to key-presses and key-releases works in my program. When a key is pressed or released, a flag is set. The Board class reades the flags every game-loop cycle and reacts accordingly.
As I said, the program doesn't react correctly to more than 3 keys held at a time, probably because of the keyboard. Is there a way to code a solution?
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]....
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.