So my program knows where the file is and it can read how many words it has, however, I am trying to compare words to count the occurrences of a word that i will use with a scanner.
The program says i can't convert string to a boolean which i understand but how would i be able to make it happen?
can I get an answer why it runs but doesn't allow me to find the word to look for
thanks
import java.util.*;
import java.io.*;
public class wordOccurence {
public static void main(String[] args) throws IOException {
{
int wordCount=0;
int word =0;
Scanner scan=new Scanner(System.in);
System.out.println("Enter file name");
System.out.println("Enter the word you want to scan");
String fileName=scan.next().trim();
Scanner scr = new Scanner(new File(fileName));
// your code goes here ...
while(scr.nextLine()){
String word1 = scr.next();
if (word1.equals(scr)){
word++;
}
}
System.out.println("Total words = " + word);
}
}
}
At present you are only checking if there is a next line available:
while(scr.hasNextLine()){
but you are not fetching it. Its like you are staying at the same position in the file forever.
To fetch the next line, you can make use of
scanner.nextLine()
Related
Infinite loop using System.in and scanner.hasNext()
While taking input from user and storing it in a list newcomer(like me) generally thinks of using Scanner class for input and check for next input from user with hasNext() method as below. But often forgets the program will keep asking the user to provide input never endingly. What happens is as each time user press enter the hasNext() method thinks another input is generated and loop continues (Keep in mind pressing enter multiple times wont make a difference).
import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;
public class App {
public static void main(String[] args) throws Exception {
Scanner scanner = new Scanner(System.in);
List<String> wordsList = new ArrayList<String>();
while (scanner.hasNextLine())
wordsList.add(scanner.nextLine()); // Keeps asking user for inputs (never ending loop)
scanner.close();
for (String word : wordsList)
System.out.println(word);
}
}
Que. What are the working alternatives for above process which let user dynamically decide number of inputs without mentioning the total inputs anywhere.
Since you require that the user can enter any valid String as input, then you can:
Option 1:
The user can enter the number of entries they are going to give, before they give them. So then you only need to loop for the requested number of times. For example:
import java.util.Scanner;
public class App {
public static void main(String[] args) throws Exception {
Scanner scanner = new Scanner(System.in);
System.out.print("Enter number of entries: ");
String[] wordsArray = new String[scanner.nextInt()];
scanner.nextLine(); //Skip the end of the line which contains the user's number of entries.
for (int i = 0; i < wordsArray.length; ++i) {
System.out.print("Entry " + (i + 1) + ": ");
wordsArray[i] = scanner.nextLine();
}
for (String word : wordsArray)
System.out.println(word);
}
}
Option 2:
If even the user does not know from the beggining how many entries they want, then you can ask them after every entry, like so:
import java.util.ArrayList;
import java.util.Scanner;
public class App {
public static void main(String[] args) throws Exception {
Scanner scanner = new Scanner(System.in);
ArrayList<String> wordsList = new ArrayList<>();
do {
System.out.print("Entry " + (wordsList.size() + 1) + ": ");
wordsList.add(scanner.nextLine());
System.out.print("Enter an empty/blank line to insert another word, or anything else to stop and exit: ");
}
while (scanner.nextLine().trim().equals(""));
for (String word : wordsList)
System.out.println(word);
}
}
I know that this (the second) option may be a bit boring for the user to enter every time if they want to quit or not, but the only thing they have to do in order to quit the program (from the second option) is to type anything which will produce a non empty/blank line. They can simply hit a single ENTER key to continue giving entries.
I'm trying to make a scanner that reads a file and deletes the spaces between each word. I can get this much but I can't get it to where they stay on the same line. I can't get the program to read a line, delete the spaces, and then go to the next line. This is the text from my practice project:
four score and
seven years ago our
fathers brought forth
on this continent
a new
nation
I'm currently only getting the first line
and this is my code:
import java.util.*;
import java.io.*;
public class CollapseSpace {
public static void main (String[] args) throws FileNotFoundException{
Scanner fileInput = new Scanner(new File ("textwithspaces.txt"));
String nextLine = fileInput.nextLine();
Scanner lineInput = new Scanner(nextLine);
while(fileInput.hasNext()){
nextLine = fileInput.nextLine();
while(lineInput.hasNext()){
System.out.print(lineInput.next() + " "); // I tried to add a fileInput.NextLine() to consume the line but it isn't working properly
}
System.out.println();
}
}
}
If you only need to iterate line by line and remove spaces between words then you only need one loop, sample code below should do the trick
public static void main (String[] args) throws FileNotFoundException{
final Scanner fileInput = new Scanner(new File ("src/main/resources/textwithspaces.txt"));
while(fileInput.hasNext()){
final String nextLine = fileInput.nextLine();
// remove all spaces
final String lineWithOutSpaces = nextLine.replaceAll("\\s+","");
System.out.println(lineWithOutSpaces);
}
}
First of all, you shouldn't be using * to import classes. It is generally thought of as "bad practice" since it can interfere with your own classes, also it is not very explicit.
You need to loop the nextLine method inside your own loop. And also using a replaceAll method of the string would be good.
I have shown an example below:
import java.util.Scanner;
import java.io.File;
import java.io.FileNotFoundException;
class Main {
public static void main(String[] args) throws FileNotFoundException {
// Create an object to represent a text file
File file = new File("textwithspaces.txt");
// Create a scanner with the text file as argument
Scanner scannerWithFile = new Scanner(file);
// Continue as long as it has a next line
do {
// Replace strings
String thisLine = scannerWithFile.nextLine();
// Only print the line out if not empty
if (!thisLine.isEmpty()) {
// Replace all spaces
thisLine = thisLine.replaceAll(" ", "");
// Print
System.out.println(thisLine);
}
} while (scannerWithFile.hasNext());
}
}
I also switched your while loop to a do while loop, this is so you can just instantly go into the loop without having to check for a condition first, it is done before next iteration.
Your biggest problem is that you declared nextLine = fileInput.nextLine(); outside of the loop, and then used that in Scanner lineInput = new Scanner(nextLine); so it becomes the first line of the text, but then never changes.
I also agree with the other comment that says you shouldn't be using *, it's considered bad practice to import broadly like that, as you're importing a whole lot of stuff you won't be using.
I reconstructed your code to make it work.
import java.util.Scanner;
import java.io.File;
import java.io.FileNotFoundException;
public class Main {
public static void main (String[] args) throws FileNotFoundException{
Scanner fileInput = new Scanner(new File ("textwithspaces.txt"));
while(fileInput.hasNext()){
String nextLine = fileInput.nextLine();
Scanner lineInput = new Scanner(nextLine);
while(lineInput.hasNext()){
System.out.print(lineInput.next() + " ");
}
System.out.println();
}
}
}
I am trying to print a line from the listed file, which contains a word stated. But the program does nothing. Can someone help me with the code? Thanks
import java.io.File;
import java.util.ArrayList;
import java.util.Scanner;
public class SearchingArrayLists {
public static void main(String[] args) throws Exception {
ArrayList names = new ArrayList();
Scanner scan = new Scanner(new File("random.txt"));
while (scan.hasNext()){
names.add(scan.next());
}
if (names.contains("legal")){
System.out.println(scan.next());
}
scan.close();
}
}
UPDATE:
Sorry, removed the loop. the file contains random text where the word "legal" is in there. the file was read by the scanner beforehand.
System.out.println(scan.next()); will throw an exception, since you are calling it after you consumed all the input in the while (scan.hasNext()) loop.
But it may not even reach that exception if your names list doesn't contain an exact match to the String "legal".
Scanner scan = new Scanner(new File("random.txt"));
String name = "" ;
while (scan.hasNextLine()){
name = scan.nextLine();
if (name.contains("legal")){
System.out.println(name);
}
}
scan.close();
Try above code , you even don't need list. I have not compiled it , so remove if any syntax error you got.
I'm trying to do some homework for my computer science class and I can't seem to figure this one out. The question is:
Write a program that reads a line of text and then displays the line, but with the first occurrence of hate changed to love.
This sounded like a basic problem, so I went ahead and wrote this up:
import java.util.Scanner;
public class question {
public static void main(String[] args)
{
Scanner keyboard = new Scanner(System.in);
System.out.println("Enter a line of text:");
String text = keyboard.next();
System.out.println("I have rephrased that line to read:");
System.out.println(text.replaceFirst("hate", "love"));
}
}
I expect a string input of "I hate you" to read "I love you", but all it outputs is "I". When it detects the first occurrence of the word I'm trying to replace, it removes the rest of the string, unless it's the first word of the string. For instance, if I just input "hate", it will change it to "love". I've looked at many sites and documentations, and I believe I'm following the correct steps. If anyone could explain what I'm doing wrong here so that it does display the full string with the replaced word, that would be fantastic.
Thank you!
Your mistake was on the keyboard.next() call. This reads the first (space-separated) word. You want to use keyboard.nextLine() instead, as that reads a whole line (which is what your input is in this case).
Revised, your code looks like this:
import java.util.Scanner;
public class question {
public static void main(String[] args)
{
Scanner keyboard = new Scanner(System.in);
System.out.println("Enter a line of text:");
String text = keyboard.nextLine();
System.out.println("I have rephrased that line to read:");
System.out.println(text.replaceFirst("hate", "love"));
}
}
Try getting the whole line like this, instead of just the first token:
String text = keyboard.nextLine();
keyboard.next() only reads the next token.
Use keyboard.nextLine() to read the entire line.
In your current code, if you print the contents of text before the replace you will see that only I has been taken as input.
As an alternate answer, build a while loop and look for the word in question:
import java.util.Scanner;
public class question {
public static void main(String[] args)
{
// Start with the word we want to replace
String findStr = "hate";
// and the word we will replace it with
String replaceStr = "love";
// Need a place to put the response
StringBuilder response = new StringBuilder();
Scanner keyboard = new Scanner(System.in);
System.out.println("Enter a line of text:");
System.out.println("<Remember to end the stream with Ctrl-Z>");
String text = null;
while(keyboard.hasNext())
{
// Make sure we have a space between characters
if(text != null)
{
response.append(' ');
}
text = keyboard.next();
if(findStr.compareToIgnoreCase(text)==0)
{
// Found the word so replace it
response.append(replaceStr);
}
else
{
// Otherwise just return what was entered.
response.append(text);
}
}
System.out.println("I have rephrased that line to read:");
System.out.println(response.toString());
}
}
Takes advantage of the Scanner returning one word at a time. The matching will fail if the word is followed by a punctuation mark though. Anyway, this is the answer that popped into my head when I read the question.
Hi I'm in a programming class over the summer and am required to create a program that reads input from a file. The input file includes DNA sequences ATCGAGG etc and the first line in the file states how many pairs of sequences need to be compared. The rest are pairs of sequences. In class we use the Scanner method to input lines from a file, (I read about bufferedReader but we have not covered it in class so not to familiar with it) but am lost on how to write the code on how to compare two lines from the Scanner method simultaneously.
My attempt:
public static void main (String [] args) throws IOException
{
File inFile = new File ("dna.txt");
Scanner sc = new Scanner (inFile);
while (sc.hasNextLine())
{
int pairs = sc.nextLine();
String DNA1 = sc.nextLine();
String DNA2 = sc.nextLine();
comparison(DNA1,DNA2);
}
sc.close();
}
Where the comparison method would take a pair of sequences and output if they had common any common characters. Also how would I proceed to input the next pair, any insight would be helpful.. Just stumped and google confused me even further. Thanks!
EDIT:
Here's the sample input
7
atgcatgcatgc
AtgcgAtgc
GGcaAtt
ggcaatt
GcT
gatt
aaaaaGTCAcccctccccc
GTCAaaaaccccgccccc
aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
gctagtacACCT
gctattacGcct
First why you are doing:
while (sc.hasNextLine())
{
int pairs = sc.nextLine();
While you have pairs only in one line not pairs and two lines of input, but number of lines once? Move reading pairs from that while looop and parse it to int, then it does not matter but you could use it to stop reading lines if you know how many lines are there.
Second:
throws IOException
Might be irrelevant but, really you don't know how to do try catch and let's say skip if you do not care about exceptions?
Comparision, if you read strings then string has method "equals" with which you can compare two strings.
Google will not help you with those problems, you just don't know it all, but if you want to know then search for basic stuff like type in google "string comparision java" and do not think that you can find solution typing "Reading two lines from an input file using Scanner" into google, you have to go step by step and cut problem into smaller pieces, that is the way software devs are doing it.
Ok I have progz that somehow wokrked for me, just finds the lines that have something and then prints them out even if I have part, so it is brute force which is ok for such thing:
import java.io.File;
import java.io.IOException;
import java.util.Scanner;
public class program
{
public static void main (String [] args) throws IOException
{
File inFile = new File ("c:\\dna.txt");
Scanner sc = new Scanner (inFile);
int pairs = Integer.parseInt(sc.nextLine());
for (int i = 0; i< pairs-1; i++)
{
//ok we have 7 pairs so we do not compare everything that is one under another
String DNA1 = sc.nextLine();
String DNA2 = sc.nextLine();
Boolean compareResult = comparison(DNA1,DNA2);
if (compareResult){
System.out.println("found the match in:" + DNA1 + " and " + DNA2) ;
}
}
sc.close();
}
public static Boolean comparison(String dna1, String dna2){
Boolean contains = false;
for (int i = 0; i< dna1.length(); i++)
{
if (dna2.contains(dna1.subSequence(0, i)))
{
contains = true;
break;
}
if (dna2.contains(dna1.subSequence(dna1.length()-i,dna1.length()-1 )))
{
contains = true;
break;
}
}
return contains;
}
}