HashMap Keys To String Array
Dec 21, 2014I 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?
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HashMap / How To Get Size Of Value And NOT The Keys
Apr 5, 2014I 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].....
Getting Keys From Values In Hashmap
Feb 9, 2014I 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 To Print Out All Keys Currently Stored In A HashMap
Jul 4, 2014I 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.
HashMap - Return Multiple Keys -OR- Values
Dec 13, 2014Here 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?
Compiler Warnings When Using SortedSet To Process HashMap Keys In Order
Feb 16, 2015My 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.
Convert JSON String To HashMap In Java
Sep 9, 2014How can I convert JSON string to HashMap. My JSON string is like
{
"AvailableDeliveries": {
"500": {
"code": "INOFFICE",
"desc": "In Office",
"id": 500,
[code]....
I looked on other examples which have collection of object but I have this extra top level object "AvailableDeliveries" not sure how to handle that level.
How To Use Regex As A Key In Hashmap To Match Given String With Key In Java
Apr 3, 2014I have a table which contains list of regular expression and its corresponding value.I have to fetch those value and put it HASHMAP where regex as key.I have to compare the each key with the given string(input) and If matches I have to get the corresponding Value for the regex.
View Replies View RelatedHashMap - Turning String Into Integer And Storing Accordingly
Oct 2, 2014When learning HashMaps in C++ I had to create the whole algorithm. In the code I created I could simply place a string into the method and it would store the names for me by turning the string into a integer and storing is accordingly. If there was a collision it would grow linearly at that location.
//play with Hash Tables
void getNames(String names) {
HashMap<String, Integer> map = new HashMap<String, Integer>();
map.put(names,22);
}
How can I do this in Java. I read about them and look at examples and they all for the most part look like this.
How To Store A File In Hashmap Or 2D Array
Sep 25, 2014I 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]....
Putting Values From 2D Array To HashMap
Apr 9, 2014I 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.
Going Through All The Keys On Keyboard One At A Time
Jul 14, 2014I 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] .....
JPA Primary Key From Two Foreign Keys
Oct 22, 2010I 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?
Accepting String And String Array In Just ONE Method?
Mar 18, 2014Code a Java method that accepts a String array and a String. The method should return true if the string can be found as an element of the array and false otherwise. Test your method by calling it from the main method which supplies its two parameters (no user input required). Use an array initialiser list to initialise the array you pass. Test thoroughly.
public class test {
public static void main(String[] args) {
Printhelloworld();
String[] verbs = {"go", "do", "some", "homework"};
printArrays(verbs);
[Code] .....
How To Compare String To Each Element Of String Array
Mar 28, 2014How do I compare a String to each element of a string array?
For example:
int headscount = 0;
if (coins[i].equals("heads")){
headscount++;
System.out.println("b" + headscount);
}
This doesn't give me the right value because the IDE says that equals() is an incompatible type. I also tried changing the "heads" to an variable, but the results remains the same.
I would prefer using an Array!
String Split Method To String Array
Sep 21, 2014So I'm creating a class which when given three inputs uses them as sides of a triangle and tells ther user what type of triangle it is, or if the input is invalid, tells them why it is invalid. I'm readin the input as a string and then trying to split it into a string array, from there checking to see if it has 3 elements.. in which the data is good at that point, and then converting them to ints and checking to see if they're negative ansd finally checking to see if they can work as sides of a triangle ie a+b >c, a+c >b , b+c >a.
I'm trying to split it into an array of strings but am getting an error, and can't seem to figure out why as this should be working from what I've read of the string.split method online.
import java.util.*;
public class TriangleTest{
private int sideA;
private int sideB;
private int sideC;
public static void main(String[] args){
TriangleTest triangle = new TriangleTest("3 4 5");
[Code] ....
The output reads [Ljava.lang.String;@15db9742
Cannot Assign Cloned String Array To Generic Type Array
Jun 21, 2014I have the following code in which I am looping through the rows of one array (composed of Strings) and copying it to another array. I am using .clone() to achieve this and it seems work as it changes the memory location of the rows themselves. I did notice that the String objects are still pointing to the same location in memory in both arrays but I won't worry about that for now, at the moment I just want to understand why the array I am cloning is not successfully assigning to the other array.
This is the incorrect line: ar[r] = maze[r].clone();
My code:
private String[][] maze = {{"*","*","*"," ","*","*","*","*","*","*"},
{"*"," ", "*"," "," "," ","*"," ","*","*"},
{"*"," ","*","*","*"," ","*"," ","*","*"},
{"*"," "," "," "," "," "," "," "," ","*"},
{"*","*","*","*","*"," ","*","*","*","*"},
{"*","*","*","*","*"," ","*","*","*","*"}};
//private String[][] mazeCopy = copyMaze(new String[6][10]);
private <T> T[][] copyMaze(T[][] ar){
for (int r = 0; r < ar.length; r++){
ar[r] = maze[r].clone();
}
return ar;
}
My compiler says: Required: T[]. Found: java.lang.String[]
Since ar[r] is an array and .clone() also returns an array why is this line incorrect.
JSF :: SQL Database - CRUD With Foreign Keys
Aug 12, 2014I 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...
Hashmaps - Selecting Keys / Values
Apr 22, 2014I'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.
How To Identify Up Down Left And Right Keys With Keylistener
Apr 9, 2014I Want to identify up, down, left and right keys with the keylistener() WHATE NAME DO I IDENTIFY IT WITH
View Replies View RelatedConvert 2D Array To String Using ToString To Print Array
Apr 19, 2015Trying to convert 2D array to String using toString() to be able to print the array but when I try to use it I just get the memory location
public class Forest
{
private int h;
private int w;
private double p = 0.7;
private int[][] f;
Forest(int w, int h)
[code]....
To Decrypt Data - File Containing Keys Is Not Being Read
Aug 27, 2014I 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] ....
Binary Search Trees Theory - Sequence Of Keys?
Mar 15, 2014Suppose 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?
How To Make Moving Character By Alternating Arrow Keys
Aug 3, 2014I'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
Deep Clone Of Entities - Set Primary Keys To Null
Nov 21, 2014I 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.
Swing/AWT/SWT :: Snakes Stopped Moving When Tried Hitting Keys
Mar 28, 2014I'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]....