How would I remove the chars from the data in this file so I could sum up the numbers?
Alice Jones,80,90,100,95,75,85,90,100,90,92
Bob Manfred,98,89,87,89,9,98,7,89,98,78
I want to do this so for every line it will remove all the chars but not ints.
The following code might be useful to you, try running it once,
public static void main(String ar[])
{
String s = "kasdkasd,1,2,3,4,5,6,7,8,9,10";
int sum=0;
String[] spl = s.split(",");
for(int i=0;i<spl.length;i++)
{
try{
int x = Integer.parseInt(spl[i]);
sum = sum + x;
}
catch(NumberFormatException e)
{
System.out.println("error parsing "+spl[i]);
System.out.println("\n the stack of the exception");
e.printStackTrace();
System.out.println("\n");
}
}
System.out.println("The sum of the numbers in the string : "+ sum);
}
even the String of the form "abcd,1,2,3,asdas,12,34,asd" would give you sum of the numbers
You need to split each line into a String array and parse the numbers starting from index 1
String[] arr = line.split(",");
for(int i = 1; i < arr.length; i++) {
int n = Integer.parseInt(arr[i]);
...
try this:
String input = "Name,2,1,3,4,5,10,100";
String[] strings = input.split(",");
int result=0;
for (int i = 1; i < strings.length; i++)
{
result += Integer.parseInt(strings[i]);
}
You can make use of the split method of course, supplying "," as the parameter, but that's not all.
The trick is to put each text file's line into an ArrayList. Once you have that, move forwars the Pseudocode:
1) Put each line of the text file inside an ArrayList
2) For each line, Split to an array by using ","
3) If the Array's size is bigger than 1, it means there are numbers to be summed up, else only the name lies on the array and you should continue to the next line
4) So the size is bigger than 1, iterate thru the strings inside this String[] array generated by the Split function, from 1 to < Size (this will exclude the name string itself)
5) use Integer.parseInt( iterated number as String ) and sum it up
There you go
Number Format Exception would occur if the string is not a number but you are putting each line into an ArrayList and excluding the name so there should be no problem :)
Well, if you know that it's a CSV file, in this exact format, you could read the line, execute string.split(',') and then disregard the first returned string in the array of results. See Evgenly's answer.
Edit: here's the complete program:
class Foo {
static String input = "Name,2,1,3,4,5,10,100";
public static void main(String[] args) {
String[] strings = input.split(",");
int result=0;
for (int i = 1; i < strings.length; i++)
{
result += Integer.parseInt(strings[i]);
}
System.out.println(result);
}
}
(wow, I never wrote a program before that didn't import anything.)
And here's the output:
125
If you're not interesting in parsing the file, but just want to remove the first field; then split it, disregard the first field, and then rejoin the remaining fields.
String[] fields = line.split(',');
StringBuilder sb = new StringBuilder(fields[1]);
for (int i=2; i < fields.length; ++i)
sb.append(',').append(fields[i]);
line = sb.toString();
You could also use a Pattern (regular expression):
line = line.replaceFirst("[^,]*,", "");
Of course, this assumes that the first field contains no commas. If it does, things get more complicated. I assume the commas are escaped somehow.
There are a couple of CsvReader/Writers that might me helpful to you for handling CSV data. Apart from that:
I'm not sure if you are summing up rows? columns? both? in any case create an array of the target sum counters int[] sums(or just one int sum)
Read one row, then process it either using split(a bit heavy, but clear) or by parsing the line into numbers yourself (likely to generate less garbage and work faster).
Add numbers to counters
Continue until end of file
Loading the whole file before starting to process is a not a good idea as you are doing 2 bad things:
Stuffing the file into memory, if it's a large file you'll run out of memory (very bad)
Iterating over the data 2 times instead of one (probably not the end of the world)
Suppose, format of the string is fixed.
String s = "Alice Jones,80,90,100,95,75,85,90,100,90,92";
At first, I would get rid of characters
Matcher matcher = Pattern.compile("(\\d+,)+\\d+").matcher(s);
int sum = 0;
After getting string of integers, separated by a comma, I would split them into array of Strings, parse it into integer value and sum ints:
if (matcher.find()){
for (String ele: matcher.group(0).split(",")){
sum+= Integer.parseInt(ele);
}
}
System.out.println(sum);
Related
This method is supposed to:
Poke through a text file filled with 32 rows of 10 hex strings.
Break them apart using a whitespace in between each as delimiter.
Store the hex strings in an array with 10 indices.
Since I'm simulating memory I then load the array into a simulated Register class.
I've gotten it to this step, but I'm having trouble seeing why this arrayOutOfBounds exception is occurring for the arrayString[] array.
public void setRegister(Register[] r) throws FileNotFoundException{ //pokes through the
//file and extracts hexes
Scanner s = new Scanner("/Users/adpitt/Documents/document.txt"); //macOS path
Register reggie = new Register(); //holding reg
while (s.hasNextLine()) {
String str = s.nextLine(); //slam a line into the string
for(int i = 0; i <= mainMemSize-1; i++){ //iterate through array of registers
for(int j = 0; j <= this.length-1; j++){
String arrayString[] = str.split("\\s+");//smash them to
//pieces, space = delimiter
reggie.reg[j] = arrayString[j];//THIS IS WHERE THE EXCEPTION OCCURS.
//I believe it's in arrayString[j],
//not sure why.
}//complete reggie!
r[i] = reggie;//load reggie into the register array to complete mm
}
}
s.close();
}
Why are you splitting the str in the inner loop? The str value is not changing anywhere inside those for loops. Can you try moving it out of the for loops, and just after String str=s.nextLine();
Also what is this.length? what if this.length-1 is greater than 10 (assuming str.split returns 10 hex strings, as per your initial description)?
I suppose to write a Java program using array and method follows: It reads a sequence of strings, each on a separate line, and stores them in an array, let call it input1, with one string per cell, in the order they were read. The sequence ends with an empty line: one with a String of length 0. Same thing with 2nd sequence.Then prints the 1st sequence and 2nd sequence. And then create an array that contains all of the elements of the above two arrays. Merging is done by alternating between the arrays: that is, the first cell of input1 is copied followed by the first cell of input2. Then the second cell of input1 is copied followed by the second cell of input2. Of course, in general, the two sequences may have different lengths, so after the shorter sequence is finished, all elements of the longer sequence are simply appended to the output array. Finally, prints the merged array with 1 string each line.
import java.util.Scanner;
public class A4 {
public static void readInput(Scanner myScanner, String[] input) {
boolean streamEnded = false;
int index = 0;
while (!streamEnded && myScanner.hasNext()) {
String value = myScanner.nextLine();
if (value.length() == 0) {
streamEnded = true;
input[index] = value;
} else {
input[index] = value;
index++;
}
}
}
public static void main(String[] args) {
int size = 5;
String[] input1 = new String[size];
String[] input2 = new String[size];
String[] store = new String[size*2];
Scanner aScanner = new Scanner(System.in);
readInput(aScanner, input1);
for (int i = 0; i < input1.length; i++) {
System.out.println("input[" + i +"]" + input1[i]);
}
readInput (aScanner, input2);
for (int i = 0; i < input2.length; i++) {
System.out.println("input[" + i +"]" + input2[i]);
}
}
}
i still dont know how to merge those 2 inputs together.Can anyone show me how to do it? Thanks
Declare three arrays for sequence 1, sequence 2 and merged-sequence.
Use a variable whichToUse to store which array to be used and assign array1 to it before the while loop, then store values into array1 on the place of System.out.print, then when first reach value.length()==0 ('=' is not designed for comparing, it's a mistake in your code.), you change the whichToUse point to array2. When the second reach value.length()==0, end the reading loop. One place to be marked, declare streamEnded as a int to count how many times we reach the value.length()==0. Only exit loop while streamEnded==2.
Now you have two arrays which contains the values from file. Next step is to merge them. Use a for loop to iterate items in merged-sequence, and use loop-counter%2 to determine which array to read when assign value to merged-sequence items. after any of the array1 and array2 reaches the end, read the other array in the rest of loop.
As looks like you are new to Java, I think write code by yourself is much better than I provide the code to you. If you've any other question, just comment here.
So, I'm in need of help on my homework assignment. Here's the question:
Write a static method, getBigWords, that gets a String parameter and returns an array whose elements are the words in the parameter that contain more than 5 letters. (A word is defined as a contiguous sequence of letters.) So, given a String like "There are 87,000,000 people in Canada", getBigWords would return an array of two elements, "people" and "Canada".
What I have so far:
public static getBigWords(String sentence)
{
String[] a = new String;
String[] split = sentence.split("\\s");
for(int i = 0; i < split.length; i++)
{
if(split[i].length => 5)
{
a.add(split[i]);
}
}
return a;
}
I don't want an answer, just a means to guide me in the right direction. I'm a novice at programming, so it's difficult for me to figure out what exactly I'm doing wrong.
EDIT:
I've now modified my method to:
public static String[] getBigWords(String sentence)
{
ArrayList<String> result = new ArrayList<String>();
String[] split = sentence.split("\\s+");
for(int i = 0; i < split.length; i++)
{
if(split[i].length() > 5)
{
if(split[i].matches("[a-zA-Z]+"))
{
result.add(split[i]);
}
}
}
return result.toArray(new String[0]);
}
It prints out the results I want, but the online software I use to turn in the assignment, still says I'm doing something wrong. More specifically, it states:
Edith de Stance states:
⇒ You might want to use: +=
⇒ You might want to use: ==
⇒ You might want to use: +
not really sure what that means....
The main problem is that you can't have an array that makes itself bigger as you add elements.
You have 2 options:
ArrayList (basically a variable-length array).
Make an array guaranteed to be bigger.
Also, some notes:
The definition of an array needs to look like:
int size = ...; // V- note the square brackets here
String[] a = new String[size];
Arrays don't have an add method, you need to keep track of the index yourself.
You're currently only splitting on spaces, so 87,000,000 will also match. You could validate the string manually to ensure it consists of only letters.
It's >=, not =>.
I believe the function needs to return an array:
public static String[] getBigWords(String sentence)
It actually needs to return something:
return result.toArray(new String[0]);
rather than
return null;
The "You might want to use" suggestions points to that you might have to process the array character by character.
First, try and print out all the elements in your split array. Remember, you do only want you look at words. So, examine if this is the case by printing out each element of the split array inside your for loop. (I'm suspecting you will get a false positive at the moment)
Also, you need to revisit your books on arrays in Java. You can not dynamically add elements to an array. So, you will need a different data structure to be able to use an add() method. An ArrayList of Strings would help you here.
split your string on bases of white space, it will return an array. You can check the length of each word by iterating on that array.
you can split string though this way myString.split("\\s+");
Try this...
public static String[] getBigWords(String sentence)
{
java.util.ArrayList<String> result = new java.util.ArrayList<String>();
String[] split = sentence.split("\\s+");
for(int i = 0; i < split.length; i++)
{
if(split[i].length() > 5)
{
if(split[i].matches("[a-zA-Z]+"))
{
result.add(split[i]);
}
if (split[i].matches("[a-zA-Z]+,"))
{
String temp = "";
for(int j = 0; j < split[i].length(); j++)
{
if((split[i].charAt(j))!=((char)','))
{
temp += split[i].charAt(j);
//System.out.print(split[i].charAt(j) + "|");
}
}
result.add(temp);
}
}
}
return result.toArray(new String[0]);
}
Whet you have done is correct but you can't you add method in array. You should set like a[position]= spilt[i]; if you want to ignore number then check by Float.isNumber() method.
Your logic is valid, but you have some syntax issues. If you are not using an IDE like Eclipse that shows you syntax errors, try commenting out lines to pinpoint which ones are syntactically incorrect. I want to also tell you that once an array is created its length cannot change. Hopefully that sets you off in the right directions.
Apart from syntax errors at String array declaration should be like new String[n]
and add method will not be there in Array hence you should use like
a[i] = split[i];
You need to add another condition along with length condition to check that the given word have all letters this can be done in 2 ways
first way is to use Character.isLetter() method and second way is create regular expression
to check string have only letter. google it for regular expression and use matcher to match like the below
Pattern pattern=Pattern.compile();
Matcher matcher=pattern.matcher();
Final point is use another counter (let say j=0) to store output values and increment this counter as and when you store string in the array.
a[j++] = split[i];
I would use a string tokenizer (string tokenizer class in java)
Iterate through each entry and if the string length is more than 4 (or whatever you need) add to the array you are returning.
You said no code, so... (This is like 5 lines of code)
I got a one dimensional array of strings in java, in which i want to change all strings to lowercase, to afterwards compare it to the original array so i can have the program check whether there are no uppercase chars in my strings/array.
i've tried using x.toLowercase but that only works on single strings.
Is there a way for me to convert the whole string to lowercase?
Kind regards,
Brand
arraylist.stream().map(s -> s.toLowerCase()).collect(Collectors.toList())
may help you
If you want a short example, you could do the following
String[] array = ...
String asString = Arrays.toString(array);
if(asString.equals(asString.toLowerCase())
// no upper case characters.
String array[]= {"some values"};
String str= String.join(',',array);
String array_uppercase[]=str.toLowerCase().split(',');
Just two line
String[] array = {"One", "Two"};
for(int i=0;i<array.length;i++){
if(!array[i].equals(array[i].toLowerCase()))
System.out.println("It contains uppercase char");
array[i] = array[i].toLowerCase();
}
for(int i=0;i<array.length;i++)
System.out.println(array[i]);
OUTPUT:
It contains uppercase char
It contains uppercase char
one
two
There's no easy way to invoke a method on every element of a collection in Java; you'd need to manually create a new array of the correct size, walk through the elements in your original array and sequentially add their lowercased analogue to the new array.
However, given what you're specifically trying to do, you don't need to compare the whole array at once to do this, and incur the cost of copying everything. You can simply iterate through the array - if you find an element which is not equal to its lowercase version, you can return false. If you reach the end of the array without finding any such element, you can return true.
This would in fact be more efficient, since:
you get to short-circuit further evaluation if you find an element that does have uppercase characters. (Imagine the case where the first element of a million-string array has an uppercase; you've just saved on a million calls to lowercase()).
You don't have to allocate memory for the whole extra array that you won't be using beyond the comparison.
Even in the best case scenario, your proposed scenario would involve one iteration through the array to get the lowercase versions, then another iteration through the array to implement the equals. Doing both in a single iteration is likely to be more efficient even without the possibility of short-circuiting.
Previously we used (In Java < 8)
String[] x = {"APPLe", "BaLL", "CaT"};
for (int i = 0; i < x.length; i++) {
x[i] = x[i].toLowerCase();
}
Now in Java8 :
x= Arrays.asList(x).stream().map(String::toLowerCase).toArray(String[]::new);
Two steps are needed:
Iterate over the array of Strings
Convert each one to lower case.
you can convert the array of strings to single string and then convert it into lower case and please follow the sample code below
public class Test {
public static void main(String[] args) {
String s[]={"firsT ","seCond ","THird "};
String str = " ";
for (int i = 0; i < s.length; i++) {
str = str + s[i];
}
System.out.println(str.toLowerCase());
}
}
import java.util.*;
public class WhatEver {
public static void main(String[] args) {
List <String> list = new ArrayList();
String[] x = {"APPLe", "BaLL", "CaT"};
for (String a : x) {
list.add(a.toLowerCase);
}
x = list.toArray(new String[list.size()]);
}
}
The following code may help you
package stringtoupercasearray;
import java.util.Scanner;
/**
*
* #author ROBI
*/
public class StringToUperCaseArray {
/**
* #param args the command line arguments
*/
public static void main(String[] args) {
int size;
String result = null;
System.out.println("Please enter the size of the array: ");
Scanner r=new Scanner(System.in);
size=r.nextInt();
String[] s=new String[size];
System.out.println("Please enter the sritngs:");
for(int i=0;i<s.length;i++){
s[i]=r.next();
}
System.out.print("The given sritngs are:");
for (String item : s) {
//s[i]=r.nextLine();
System.out.print(item+"\n");
}
System.out.println("After converting to uppercase the string is:");
for (String item : s) {
result = item.toUpperCase();
System.out.println(result);
}
}
}
You can do it with a single line of code. Just copy and paste the following snippet, without any looping at all.
String[] strArray = {"item1 Iteme1.1", "item2", "item3", "item4", "etc"}//This line is not part of the single line (=D).
String strArrayLowerCase[] = Arrays.toString(strArray).substring(1)
.replace("]", "").toLowerCase().split(",");
Happy String Life. =D
I'm wondering how I could grab each nth lines from a String, say each 100, with the lines in the String being seperated with a '\n'.
This is probably a simple thing to do but I really can't think of how to do it, so does anybody have a solution?
Thanks much,
Alex.
UPDATE:
Sorry I didn't explain my question very well.
Basically, imagine there's a 350 line file. I want to grab the start and end of each 100 line chunk. Pretending each line is 10 characters long, I'd finish with a 2 seperate arrays (containing start and end indexes) like this:
(Lines 0-100) 0-1000
(Lines 100-200) 1000-2000
(Lines 200-300) 2000-3000
(Lines 300-350) 3000-3500
So then if I wanted to mess around with say the second set of 100 lines (100-200) I have the regions for them.
You can split the string into an array using split() and then just get the indexes you want, like so:
String[] strings = myString.split("\n");
int nth = 100;
for(int i = nth; i < strings.length; i + nth) {
System.out.println(strings[i]);
}
String newLine = System.getProperty("line.separator");
String lines[] = text.split(newLine);
Where text is string with your whole text.
Now to get nth line, do e.g.:
System.out.println(lines[nth - 1]); // Minus one, because arrays in Java are zero-indexed
One approach is to create a StringReader from the string, wrap it in a BufferedReader and use that to read lines. Alternatively, you could just split on \n to get the lines, of course...
String[] allLines = text.split("\n");
List<String> selectedLines = new ArrayList<String>();
for (int i = 0; i < allLines.length; i += 100)
{
selectedLines.add(allLines[i]);
}
This is simpler code than using a BufferedReader, but it does mean having the complete split string in memory (as well as the original, at least temporarily, of course). It's also less flexible in terms of being adapted to reading lines from other sources such as a file. But if it's all you need, it's pretty straightforward :)
EDIT: If the start indexes are needed too, it becomes slightly more complicated... but not too bad. You probably want to encapsulate the "start and line" in a single class, but for the sake of brevity:
String[] allLines = text.split("\n");
List<String> selectedLines = new ArrayList<String>();
List<Integer> selectedIndexes = new ArrayList<Integer>();
int index = 0;
for (int i = 0; i < allLines.length; i++)
{
if (i % 100 == 0)
{
selectedLines.add(allLines[i]);
selectedIndexes.add(index);
}
index += allLines[i].length + 1; // Add 1 for the trailing "\n"
}
Of course given the start index and the line, you can get the end index just by adding the line length :)