Count Number Of Occurrences Of A String In Array List?
Apr 6, 2015
I am trying to count the number of occurrences of a string in an array list. I used the following code:
int count = Collections.frequency(strings, search);
strings is the name of the array list and search is the string that I am trying to count the number of occurrences of. My program compiles correctly, but when I enter the string to search for, I get the following error: "Exception in thread "main" java.lang.NullPointerException at java.util.Collections.frquency(Collections.java:37 18)
Why am I getting this error message and how do I fix it?
the number of occurrences of a specified character in a string...i tried to do the program occurrences in a given string and i tried the code as below.
code:
import java.util.*; public class Occurrence { public static void main(String[] args) { Scanner input = new Scanner(System.in);
//read the file //make the numbers 1 string line //count the number of repetitiveness in the string for the numbers //display four lowest ones
import java.io.*; import java.util.*; public class Lottery2
[Code] ....
when I run it the array gets sorted but how do i keep the data in other words
what it is supposed to do is grab numbers from a file, and give me the lowest 4 numbers back. I know the numbers using the array but how do i pull out the lowest 4 and keep the data true no matter what numbers or how many of them are in the file.
Write a program using a while-loop (and a for-loop) that asks the user to enter a string, and then asks the user to enter a character. The program should count and display the number of times that the specified character appears in the string. (So, you will have two separate program codes, one using a while-loop and the other one using a for-loop.)
Example: Enter a string: "Hello, JAVA is my favorite programming language." Enter a character: e The number of times the specified character appears in the string: 3
I don't even know where to begin I've only got this
import java.util.Scanner; public class letterCounter { public static void main(String [] args) { Scanner sc = new Scanner(System.in); System.out.println("Enter a string"); String myString = sc.nextLine(); System.out.println("Enter a letter"); String letter = sc.nextLine(); } }
I'm trying to write a program that counts the number of times each number in an array occurs. In theory I understand how it work, you take the first element in the array, compare it again the rest of the array and any time it occurs in the array you increment a counter by 1. Then move onto the next element A[1] and so on...
This is what I've done so far :
public static void main(String[] args) { int[] array = {5,6,2,5,2,2,0,1,6}; int count = 0; for(int i = 0; i <array.length; i++) { int val = array[i]; for(int j = i+1; j<array.length; j++)
[Code] .....
I think I'm on the right track as it correctly prints out the frequency of the first 3 elements, but I'm definitely going wrong somewhere as it just doesn't do it right after that!
I have problems getting the right number of times for each number of the array. Here is my code:
public static void main(String[] args) { int[] a = { 3, 13, 5, 9, 13, 6, 9, 13, 2, 3 }; int num = 3; int count = numbers(a, num); for (int i = 0; i < a.length; i++) {
I am attempting to count the unique strings (a.k.a flowers) in the array along with a count of any duplicates. An example is embedded in my code below. I've only pasted the part of the program I am having trouble with. I can't figure out what I am doing incorrectly.
private void displayFlowers(String flowerPack[]) { // TODO: Display only the unique flowers along with a count of any duplicates /* * For example it should say
I have to write some code to take names from the user and then order them in alphabetical order and then print them out which i have managed to do. However, i can't get it to count the characters in the names that the user enters or count the amount of vowels in the names.
This is the code ive written:
import javax.swing.JOptionPane; import java.util.Arrays; String[] names = new String[9]; int i; names[0] = JOptionPane.showInputDialog("Please enter a name"); names[1] = JOptionPane.showInputDialog("Please enter a name");
find whether it is a repetition free number or not. If it is, print the same number(x), else if it has repetitions then print the number of occurrences of the first repetitive digit you encounter.
I have an array with the following characters {'E', 'L','E','P','H','A','N','T','P','O'}
now, I need an array that will store the first array such that only the occurence occurs e.g {'E','L','P','H','A','N','T','O'} Notice that the characters 'E' and 'P' occur twice and as a result were not repeated the second time in the new array.
How would one go about this using the counting elements technique?
I tried this but not sure how to use the counting elements technique.
char [] arr = new char{'E', 'L','E','P','H','A','N','T','P','O'}; char[] bucket = new char[(arr[0] * arr.length)]; for (int i = 0; i < len; i++) bucket[arr[i]]++;
Write a program that removes all the occurrences of a specified string from a text file. For example, invoking java Exercise14_11 John filename removes the string John from the specified file. Your program should get the arguments from the command line.
I have a problem.
Text document is Match.txt Match.txt contains a string: "Open the door John"
I tried to create a new file named doc.txt where to put the text from the Match.txt without John word
//to read from document Scanner output = new Scanner("Match.text"); //to write to document PrintWriter write = new PrintWriter("doc.txt"); //copy from original document String copy = ""; while(output.hasNextLine())
As you notice, each character is seperated by a hyphen (serving as its delimiter). I want to only go through 10 lines in the text, instead of all 20 of them. So, I wrote the program in such a way that I intend to reach into the indices of each character in the text file. Since there are six characters in each line so that means there are 6 indices - and there are 10 lines I only want to go through. So, 6 indices times 10 lines equals 60 indices. Hence, there are only 60 indices I need to go through. In that manner, it's like I have gone through only 10 lines through that way.
It compiled perfectly fine but upon running it, I ran through an error in the black DOS screen that says
"java.lang.ArrayIndexOutofBoundsException: 6 ".
How do I work around that?
The code I wrote is shown below...
import java.io.*; import java.util.*; public class hotandcoldclusterdeterminer_test { public static void main (String args [])throws IOException {
gather sales amount for the week display the total of sales display the average of sale display the highest sale amount display the lowest sale amount
using occurrences determine how many times the amount occurred for the week
make a sales main make a sales data
This is what i have so far but I'm confused on how to start the occurrence and where it would be placed in order to get the information from the array
public class SalesData { private double[] sales; // The sales data /** The constructor copies the elements in an array to the sales array. @param s The array to copy. */ public SalesData(double[] s) {
Im making a simple code to add an array to a List (the code im referring to is <String> )
import java.util.*; public class L5_ArrayListProgram { public static void main(String[] args){ String[] things = {"lasers","ghouls", "food", "dark"}; List<String>list1 = new ArrayList<String>(); for(String x: things) list1.add(x);
My simple question is - what are the <String> ...<String> for? I understand it makes the list1 variable a string, but why is it made like this? do we usualy use <String> when we need to make a variable a String?
Suppose that you have an ArrayList and that it contains String objects. Which declaration of the ArrayList requires that objects retrieved using the get method be cast to Strings before calling a String method?
I. ArrayList a = new ArrayList(); II. ArrayList<Object> a = new ArrayList<Object>; III. ArrayList<String> a = new ArrayList<String>;
A. I only B. II only C. III only D. I and II only E. I, II, and III
I know that all of these are ways to declare an Array List, but I am unfamiliar with the last two since I usually just declare my Array Lists with the first option.
Question - Given an specific integer and an array of integers, find and remove all occurrences of the given integer and return an amended array. I solved it. Here is my solution -
I'm trying to generate a random word from the array that I have made including the words by making it corresponding with a randomly generated number. So for example, if the number generated is 0, then the word that the person has to guess would be "AUNT". How would I transfer the randomly generated number from one method into the array method to get the word the person has to guess?
Write a program called Word Guessing Game. Open the file FourLetterWords.txt and write the contents into an array of Strings (the file has 87 words in it). Then use a randomly generated number between 0 and 86 to select a word. The player will then try to guess the word selected by the game. The player is allowed 7 tries, if the player does not guess the word on the 7th try he/she losses. Display the letter of the word as they are guessed in the correct order, you will also display the incorrect letters. The game is over when:
- The player completes the word, or guesses the whole word correctly. - The player does not guess the word in seven tries. The player must also be allowed to terminate the game. The game must have at least 5 classes: - Main Class - Class to return a random integer between 0 and 86. - Class to return a populated array of 87, 4 letter words. - Class to return a character that the player enters from the keyboard. - Class to display both the correctly guessed letters and the incorrect letters.
My code (it is not complete, my attempt to do what I am trying to do is obviously not working.)
import java.util.Scanner; public class WordGuessingGame { public static void main(String[] args) { final int NUMBER_OF_WORDS = 87; RandomWordGenerator.random(NUMBER_OF_WORDS);
I'm having a hard time with this problem, this is what I have, but I can not use two integers, I have to use one integer and a string...
This is the question:
Write a method called printStrings that accepts a String and a number of repetitions as parameters and prints that String the given number of times. For example, the call:
printStrings("abc", 5);
will print the following output: abcabcabcabcabc
This is what I attempted:
public class printStringsproject { public static void printStrings(int abc, int number) { for (int i = 1; i <= number; i++) { System.out.print("abc"); } } public static void main(String[] args) { printStrings(1, 5); } }
So I have 2 args[] one that reads the file name in the same directory and the other that tries to count how many of any letter (maybe even words) in the txt file ....
We have been given an assignment to create a small library, with the following classes Library, Book, Author and Copy. With a given class Biblio which has predefined code and adds the books to the class book in an arraylist in Class Copy.
The UML Domain is attached so you know the flow of the classes Everything is working fine and the generated output is correct.
There is just one method in class Library that is not working, the int method has to count the number of Copy's based on the Class Book (String):
I have to go through the Arraylist in Class Copy and look for a specific book and return the number of copy's.
I have tried multiple steps using a for loop Now I have found a similar post the uses hashset, I have tried below code but the return comes back with 0. (There are 3 copy's)
