I am trying to take a user entered word or phrase and put the characters in alphabetical order by putting them in a list and sorting the list. Here is my code:
import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;
public class SortAlphabetically {
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
List<Character> alpha = new ArrayList<Character>();
System.out.println("Enter a word or phrase");
StringBuilder input = new StringBuilder(scanner.next());
scanner.close();
for (int i = 0; i < input.length(); i++) {
if (Character.isWhitespace(input.charAt(i))) {
input.deleteCharAt(i);
} else {
alpha.add(input.charAt(i));
}
}
alpha.sort(null);
System.out.println("Input sorted alphabetically: " + alpha);
}
}
However, the input seems to stop being entered into the list after a white space character. For example:
Enter a word or phrase
cba fed
Input sorted alphabetically: [a, b, c]
I tried to fix this with
if (Character.isWhitespace(input.charAt(i))) {
input.deleteCharAt(i);
}
but it doesn't seem to have done anything
scanner.next() reads a single token, so it stops at the first white space.
If you use scanner.nextLine(), it will read the entire line, including the space.
You have to use the scanner.nextLine() to get the entire line with all the white-spaces. In addition, you have a better way to implement the solution in just one line using simple java library functions in java.lang.String. Why waste lines!
System.out.println("Answer"+input.replaceAll( " ", "" ).toCharArray().toList().sort());
Related
I need to create an array of strings from user input and print the first letter of each element. I'm aware that I need to convert the array to a string somehow, but unsure how to accomplish this. I was unsuccessful with Arrays.toString
Following is my code:
import java.util.Scanner;
import java.util.Arrays;
class Main{
public static void main(String[] args){
Scanner inp = new Scanner(System.in);
System.out.println("How many names would you like to enter in this array?: ");
int numName = inp.nextInt();
String nameArray[] = new String[numName];
System.out.println("Enter the names: ");
for(int i = 0; i <= nameArray.length; i++){
nameArray[i] = inp.nextLine();
}
System.out.println(nameArray.charAt(0));
}
}
You need to iterate over every String in the Array and then print the first char. You can do this using charAt() and a loop.
for(String str : nameArray) {
System.out.println(str.charAt(0));
}
Or you can use Arrays.stream():
Arrays.stream(nameArray).forEach(e -> System.out.println(e.charAt(0)));
Also just a few problems with your code:
You are going to enter into this problem, because nextInt() does not consume the newline. Add a blank nextLine() call after nextInt()
You are looping until <= array.length which will cause an indexOutOfBounds error. You need to only loop until less than array.length
Just do another iteration over the "nameArray", and get the first character of each array element, and print it.
For example, you can use for-each:
for(String name : nameArray) {
System.out.println(name.charAt(0));
}
Arrays.stream(nameArray).map(s -> s.charAt(0)).forEach(System.out::println);
**Edit after reviewing Tormod's answer and implementing his advice.
As the title states I'm attempting to print the total number of different words after receiving a file name from command line input. I receive the following message after attempting to compile the program:
Note: Project.java uses unchecked or unsafe operations.
Note: Recompile with -Xlint:unchecked for details.
Here is my code. Any help is greatly appreciated:
import java.lang.*;
import java.util.*;
import java.io.*;
public class Project {
public static void main(String[] args) throws IOException {
File file = new File(args[0]);
Scanner s = new Scanner(file);
HashSet lib = new HashSet<>();
try (Scanner sc = new Scanner(new FileInputStream(file))) {
int count = 0;
while(sc.hasNext()) {
sc.next();
count++;
}
System.out.println("The total number of word in the file is: " + count);
}
while (s.hasNext()) {
String data = s.nextLine();
String[] pieces = data.split("\\s+");
for (int count = 0; count < pieces.length; count++)
{
if(!lib.contains(pieces[count])) {
lib.add(pieces[count]);
}
}
}
System.out.print(lib.size());
}
}
I would implement it using a HashSet Add all the words, and read out the size. If you want to make it case insensitive just manipulate all the words to uppercase or something like that. this uses some memory but...
one problem you got with the algorithm is that you do only have one "words". it only holds the words at the same line. so you only count same words at the same line.
HashSet stores strings by their hash value, and thus stores one word only one time.
construction: HashSet lib = new HashSet<>();
inside the loop: if(!lib.contains(word)){lib.add(word);}
check the word count: lib.size()
for(String s : words) {
if(s.equals(word))
count++;
}
You are comparing the words to an empty String, since it's a word it's always gonna be false.
Like Tormod said, the best would be to store the words in a HashSet, as it won't keep duplicates. Then just read out its size.
I am attempting to create a method that accepts a string as an input and returns another string that reverses the order of each sentence in the input using Stacks. For example, if the user inputs "hi there. i like red." the outputted string should be "there hi. red like i.". The following program I have created works fine for only one sentence. How could i modify the method to recognize a period, and start the method over again? Currently, if I input "hi there", the output is "there hi", which is just fine. However, if I input "hi there. i like red.", the output is "red. like i there. hi". How can I modify this reverseSentence method to recognize periods and to start over for the next sentence? Any advise or tips will be very helpful.
//Reverses the order of words inside of sentences.
import java.util.*;
import java.util.regex.*;
public class reverse {
//reverses the string using a stack
private static String reverseSentence(String inputString) {
String[] arrString = inputString.trim().split(Pattern.quote(" "));
Stack stack = new Stack();
for(String word : arrString)
{
stack.push(word);
}
StringBuilder builder = new StringBuilder();
while( !stack.isEmpty())
{
builder.append(stack.pop()).append(" ");
}
return builder.toString();
}
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
Stack<String> stack = new Stack<String>();
System.out.printf("Enter a sentence: ");
String sentence = scanner.nextLine();
if (sentence == null || sentence.length() == 0) {
System.out.println("Invalid...");
return;
}
String reverse = reverseSentence(sentence);
System.out.printf("Reversed string using stack is : %s", reverse);
while (!stack.isEmpty()) {
System.out.print(stack.pop() + " ");
}
}
}
Before splitting the input at the space, trim it by period and run the logic inside your method in a for-loop for every sentence / splitted part you got earlier.
In your main-method, instead of calling reverseSentence:
String[] sentences = sentence.trim().split(Pattern.quote("."));
for (String toReverse : sentences) {
System.out.print(reverseSentece(toReverse));
}
I know this is not perfect, but I hope to give an idea of what I mean, because I am typing on my phone.
There are two approaches that come to my mind to achieve this:
First split the string by '.', giving you a list of sentences in the string. Apply your logic to every sentence. Output every reversed sentence separated by a period.
Use your current logic, but before adding any word to stack, check if the word's last character is a period. If it is, this means it is the end of a sentence. Pop the stack till empty and display contents. (This will display the inverted sentence till here) Continue with the next word.
Hope this helps!
Use the string split method.
String[] sentences = sentence.split ("\\."); maybe?
I am in a beginners course but am having difficulty with the approach for the following question: Write a program that asks the user to enter a line of input. The program should then display a line containing only the even numbered words.
For example, if the user entered
I had a dream that Jake ate a blue frog,
The output should be
had dream Jake a frog
I am not sure what method to use to solve this. I began with the following, but I know that will simply return the entire input:
import java.util.Scanner;
public class HW2Q1
{
public static void main(String[] args)
{
Scanner keyboard = new Scanner(System.in);
System.out.println("Enter a sentence");
String sentence = keyboard.next();
System.out.println();
System.out.println(sentence);
}
}
I dont want to give away the answer to the question (for the test, not here), but I suggest you look into
String.Split()
From there you would need to iterate through the results and combine in another string for output. Hope that helps.
While there will be more simpler and easier way to do this, I'll use the basic structure- for loop, if block and a while loop to achieve it. I hope you will be able to crack the code. Try running it and let me know if there is an error.
String newsent;
int i;
//declare these 2 variables
sentence.trim(); //this is important as our program runs on space
for(i=0;i<sentence.length;i++) //to skip the odd words
{
if(sentence.charAt(i)=" " && sentence.charAt(i+1)!=" ") //enters when a space is encountered after every odd word
{
i++;
while(i<sentence.length && sentence.charAt(i)!=" ") //adds the even word to the string newsent letter by letter unless a space is encountered
{
newsent=newsent + sentence.charAt(i);
i++;
}
newsent=newsent+" "; //add space at the end of even word added to the newsent
}
}
System.out.println(newsent.trim());
// removes the extra space at the end and prints newsent
you should use sentence.split(regex) the regular expression is going to describe what separate your worlds , in your case it is white space (' ') so the regex is going to be like this:
regex="[ ]+";
the [ ] means that a space will separate your words the + means that it can be a single or multiple successive white space (ie one space or more)
your code might look like this
Scanner sc= new Scanner(System.in);
String line=sc.nextLine();
String[] chunks=line.split("[ ]+");
String finalresult="";
int l=chunks.length/2;
for(int i=0;i<=l;i++){
finalresult+=chunks[i*2]+" ";//means finalresult= finalresult+chunks[i*2]+" "
}
System.out.println(finalresult);
Since you said you are a beginner, I'm going to try and use simple methods.
You could use the indexOf() method to find the indices of spaces. Then, using a while loop for the length of the sentence, go through the sentence adding every even word. To determine an even word, create an integer and add 1 to it for every iteration of the while loop. Use (integer you made)%2==0 to determine whether you are on an even or odd iteration. Concatenate the word on every even iteration (using an if statement).
If you get something like Index out of range -1, manipulate the input string by adding a space to the end.
Remember to structure the loop such that, regardless of the whether it is an even or odd iteration, the counter increases by 1.
You could alternatively remove the odd words instead of concatenation the even words, but that would be more difficult.
Not sure how you want to handle things like multiple spaces between words or weird non-alphabetically characters in the entry but this should take care of the main use case:
import java.util.Scanner;
public class HW2Q1 {
public static void main(String[] args)
{
System.out.println("Enter a sentence");
// get input and convert it to a list
Scanner keyboard = new Scanner(System.in);
String sentence = keyboard.nextLine();
String[] sentenceList = sentence.split(" ");
// iterate through the list and write elements with odd indices to a String
String returnVal = new String();
for (int i = 1; i < sentenceList.length; i+=2) {
returnVal += sentenceList[i] + " ";
}
// print the string to the console, and remove trailing whitespace.
System.out.println(returnVal.trim());
}
}
The sentence String is expected to be a bunch of words separated by spaces, e.g. “Now is the time”.
showWords job is to output the words of the sentence one per line.
It is my homework, and I am trying, as you can see from the code below. I can not figure out how to and which loop to use to output word by word... please help.
import java.util.Scanner;
public class test {
public static void main(String[] args) {
Scanner in = new Scanner(System.in);
System.out.println("Enter the sentence");
String sentence = in.nextLine();
showWords(sentence);
}
public static void showWords(String sentence) {
int space = sentence.indexOf(" ");
sentence = sentence.substring(0,space) + "\n" + sentence.substring(space+1);
System.out.println(sentence);
}
}
You're on the right path. Your showWords method works for the first word, you just have to have it done until there are no words.
Loop through them, preferably with a while loop. If you use the while loop, think about when you need it to stop, which would be when there are no more words.
To do this, you can either keep an index of the last word and search from there(until there are no more), or delete the last word until the sentence string is empty.
Since this is a homework question, I will not give you the exact code but I want you to look at the method split in the String-class. And then I would recommend a for-loop.
Another alternative is to replace in your String until there are no more spaces left (this can be done both with a loop and without a loop, depending on how you do it)
Using regex you could use a one-liner:
System.out.println(sentence.replaceAll("\\s+", "\n"));
with the added benefit that multiple spaces won't leave blank lines as output.
If you need a simpler String methods approach you could use split() as
String[] split = sentence.split(" ");
StringBuilder sb = new StringBuilder();
for (String word : split) {
if (word.length() > 0) { // eliminate blank lines
sb.append(word).append("\n");
}
}
System.out.println(sb);
If you need an even more bare bones approach (down to String indexes) and more on the lines of your own code; you would need to wrap your code inside a loop and tweak it a bit.
int space, word = 0;
StringBuilder sb = new StringBuilder();
while ((space = sentence.indexOf(" ", word)) != -1) {
if (space != word) { // eliminate consecutive spaces
sb.append(sentence.substring(word, space)).append("\n");
}
word = space + 1;
}
// append the last word
sb.append(sentence.substring(word));
System.out.println(sb);
Java's String class has a replace method which you should look into. That'll make this homework pretty easy.
String.replace
Update
Use the split method of the String class to split the input string on the space character delimiter so you end up with a String array of words.
Then loop through that array using a modified for loop to print each item of the array.
import java.util.Scanner;
public class Test {
public static void main(String[] args) {
Scanner in = new Scanner(System.in);
System.out.println("Enter the sentence");
String sentence = in.nextLine();
showWords(sentence);
}
public static void showWords(String sentence) {
String[] words = sentence.split(' ');
for(String word : words) {
System.out.println(word);
}
}
}