JAVA: Read string letter by letter

Dave!

Hey folks,

This isn't for an assignment or anything... just for... eh... "fun" (I feel very depressed after typing that!)

I'm working on a program and one of the first things I want to do is read in a word with a Scanner. I have that, and now what I wanna do is change the string to an array of strings (with each letter being an element in this array).

I'm sure I could put it into an array no problem, if I'm able to extract each letter one at a time.

Any help? Would the next() method from the Scanner class be used here? I had a look and it's a bit hard to understand.

Cheers folks

Evil Phil

If you have a String could you not just use the ToCharArray() method to get an array of chars?

OMcGovern

String testString = "aaaaa";

for ( int i=0; i<testString.length(); i++)
{
char c = testString.charAt(i);
}

regards,
Owen

marco_polo

DaveMcG wrote: »

Hey folks,

This isn't for an assignment or anything... just for... eh... "fun" (I feel very depressed after typing that!)

I'm working on a program and one of the first things I want to do is read in a word with a Scanner. I have that, and now what I wanna do is change the string to an array of strings (with each letter being an element in this array).

I'm sure I could put it into an array no problem, if I'm able to extract each letter one at a time.

Any help? Would the next() method from the Scanner class be used here? I had a look and it's a bit hard to understand.

Cheers folks

The two suggestion above should work fine. The Scanner.next() method is only used to break up a string into smaller tokens (for example to get each of the words in a sentance). It cannot break up a String into characters as far as I know.

The default delimiter for Scanner is whitespace charachters. For example With the string "Hello there" the first call to Scanner.next() will return a string "Hello" the second call to Scanner.next() will return the string "there". But you would still have to convert these strings to char arrays using one of the methods the lads have described above.

Just as another example if it was a comma seperated list you could also use the Scanner class to break up the list.

File input.txt contains a,b,c,d

Scanner s = new Scanner(new File(input.txt)).useDelimiter(",");
Calling s.next() 4 times will return

a
b
c
d

Dave!

Cheers lads

But those methods give an array of chars.... I could do that with the toCharArray method.... I was looking to break the string into an array of strings, with each letter being an element.

Any ideas?

Probably needlessly messy, but maybe a few loops and the substring() method?

Any others?

Thanks again

Evil Phil

Convert each char in the array to a string maybe?

ianhobo

I was looking to break the string into an array of strings

so you want each letter to be in its own array? with the result being that each letter will be the first and only element in each array?

Evil Phil

No he was looking to break the string (lets call it StringA) into an array of strings with each letter of StringA being an element of that array.

OP, you need to have a read of this about now.

sicruise

String[] newStringArray = new String[yourOriginalString.length()];

for(int i=0;i<yourOriginalString.length();i++){
   newStringArray[i] = yourOriginalString.substring(i,i+1);
}

Somthing like that?? It should work but i didnt test it...

sicruise

OMcGovern wrote: »

String testString = "aaaaa";

for ( int i=0; i<testString.length(); i++)
{
char c = testString.charAt(i);
}

regards,
Owen

Your variable c will only hold the last character after the for loop runs??

Dave!

Cheers sicruise, that did the job

Evil Phil wrote: »

OP, you need to have a read of this about now.

import java.io.*;
import java.util.Scanner;

public class Cypher {

	public static void main(String[] args) 
	{
		Scanner input = new Scanner(System.in);
		System.out.print("Enter keyword: ");

		String keya = input.nextLine();
		String keyb = keya.toUpperCase();

		String[] key = new String[keyb.length()];

		for(int i=0; i < keyb.length(); i++) {
 			key[i] = keyb.substring(i,i+1);
		}

		String[] alphA = {"A", "B", "C", "D", "E", "F", "G", "H", "I", "J", "K", "L", "M", "N", "O", "P", "Q", "R", "S", "T", "U", "V", "W", "X", "Y", "Z"};	//full alphabet

		String temp;
		int count=0;

		for (int i=0; i < alphA.length; i++)
			for (int j=0; j < key.length; j++)
				if(alphA[i] == key[j]) {
					temp = alphA[i];
					for(int k=i; k < alphA.length; k++) {
						alphA[k] = alphA[k-1];
						alphA[count] = temp;
						count++;
					}
				}

		for (int l=0; l < key.length; l++)
			System.out.print(key[l]);

	}
}

...tis not finished

sicruise

DaveMcG wrote: »

Cheers sicruise, that did the job

Glad to hear it

croo

Quote:
Originally Posted by OMcGovern View Post
String testString = "aaaaa";

for ( int i=0; i<testString.length(); i++)
{
char c = testString.charAt(i);
}

regards,
Owen

Your variable c will only hold the last character after the for loop runs??

Actually the variable c won't exist after the loop... will it?
Won't it be outside of the scope?

Dave!

It will hold the last char... first iteration, holds 1st char, second iteration holds 2nd, etc., the last it'll hold the last character, then the loop will end.

Hobbes

1. For loop which feeds it into a vector then convert vector to an array.

2. toCharArray()

3. Use Pattern and Matcher classes to create Regexp to split it up.

Of everything suggested toCharArray is the best.

Hobbes

sicruise wrote: »

String[] newStringArray = new String[yourOriginalString.length()];

for(int i=0;i<yourOriginalString.length();i++){
   newStringArray[i] = yourOriginalString.substring(i,i+1);
}

Somthing like that?? It should work but i didnt test it...

That is a very messy way to do it. Your wasting time with the interaction.

Look into Arrays class.

croo

DaveMcG wrote: »

It will hold the last char... first iteration, holds 1st char, second iteration holds 2nd, etc., the last it'll hold the last character, then the loop will end.

yes that is clear.
my point was since c is define in the for block when the block ends char c will go to garbage ... so after the loop runs c won't exist

sicruise

Hobbes wrote: »

That is a very messy way to do it. Your wasting time with the interaction.

Look into Arrays class.

I hope your instructing him and not me... I wrote it so it would be easy to understand not that it would save vital clock cycles :P

sicruise

croo wrote: »

yes that is clear.
my point was since c is define in the for block when the block ends char c will go to garbage ... so after the loop runs c won't exist

I see your point that it is not accessible outside of this loop but that just makes it even more pointless :P

croo

sicruise wrote: »

I see your point that it is not accessible outside of this loop but that just makes it even more pointless :P

yes indeed... no argument there
my point was meant as a silly (on my behalf) addition in support of your point

Hobbes

sicruise wrote: »

I hope your instructing him and not me... I wrote it so it would be easy to understand not that it would save vital clock cycles :P

Better to learn to do it the correct way first time.

sicruise

Write your more efficient method here without testing it then...