Develop Reference

Create array with reversed words from user string

I am creating a program in which a user enters a string of words (Ex: I love you), and the program returns an array of the words in the string spelled backwards (Ex: I evol ouy). However, I cannot get my code to properly compile, and tried debugging, but cannot see where the problem is.
I tried to look for similar problems here on Slack, but the problems are found were concerned with rearranging words from a string, (ex: you I love), and I cannot find a problem similar to mine, involving turning string into an Array and then manipulating the array.
Scanner sc = new Scanner(System.in);
System.out.println("Enter a string to see it in reverse: ");
String userEntry = sc.nextLine();
char[] entryToChar = userEntry.toCharArray();
System.out.println(Arrays.toString(entryToChar));
String[] splitInput = userEntry.split(" ");
String reverseWord = "";
int temp;
String[] reverseString = new String[splitInput.length];
for (int i = 0; i < splitInput.length; i++)
{
String word = splitInput[i];
for (int j = word.length()-1; j >= 0; j--)
{
reverseWord = reverseWord + word.charAt(j);
}
for (int k = 0; k < splitInput.length; k++) {
temp = splitInput[i];
splitInput[i] = reverseWord[j];
reverseWord[j] = temp;
}
} System.out.println("Your sttring with words spelled backwards is " + reverseWord[j]);
I am avoiding using the 'StringBuilder' method as I have not yet studied it, and trying to see if I can get the new string using swapping, as in the code below:
temp = splitInput[i];
splitInput[i] = reverseWord[j];
reverseWord[j] = temp;

import java.util.Arrays;
import java.util.Scanner;
public class Main {
public static void main(String[] args) {
String word, reverseWord;
Scanner sc = new Scanner(System.in);
System.out.println("Enter a string to see it in reverse: ");
String userEntry = sc.nextLine();
userEntry: I love you
String[] splitInput = userEntry.split(" ");
splitInput: [I, love, you]
for (int i = 0; i < splitInput.length; i++)
{
word = splitInput[i];
reverseWord = "";
for (int j = word.length()-1; j >= 0; j--)
{
reverseWord = reverseWord + word.charAt(j);
}
splitInput[i] = reverseWord;
}
splitInput: [I, evol, uoy]
System.out.println("Your string with words spelled backwards is: " + String.join(" ", splitInput));
}
}
Your string with words spelled backwards is: I evol uoy

Your code is not getting compiled because tmp variable is declared as int while splitInput[i] is String.
The other problem is variable j is outside its block scope from where you are trying to access.
Make your logic clear before writing code to achieve correct result.

A good Java programmer should know which tools exist in the language and make use of them in her/his design appropriately. I would suggest to use the class StringBuilder, which has a method for reversing the string. Your program could look like this:
while in.hasNext() {
StringBuilder sb = in.next();
sb.reverse();
System.out.println(sb.toString());
}
If you want to write the reverse function yourself for practice then you can simply define a method that takes a string and returns a reversed string and call that method in place of sb.reverse().
Please know that String in Java is an immutable object. You cannot modify it directly. You can have modified copies returned.
StringBuilder on the other hand allows the programmer to modify the object directly as you can see in the code above.

You need to split original string into an array and then reverse each one and insert into the new array, here you can use StringBuilder as good practice.
class Testarray{
public static void main(String args[]){
String str = "I am Engineer";
String[] spArray = str.split(" ");
String farr[] = new String[spArray.length];
for(int i=0;i<spArray.length;i++){
String split = spArray[i];
farr[i]=reverseString(split);
}
for(int i=0;i<farr.length;i++){
System.out.println(farr[i]);
}
}
public static String reverseString(String str){
char ch[]=str.toCharArray();
String rev="";
for(int i=ch.length-1;i>=0;i--){
rev+=ch[i];
}
return rev;
}
}

There are a few things going on here, and I think in some places you're mixing up between strings and arrays.
Let's try to break this problem down into smaller problems.
First, we need to reverse a single word. Your first inner loop (the one that uses j) does that, so let's extract it into its own method:
public static String reverseWord(String word) {
String reverseWord = "";
for (int j = word.length()-1; j >= 0; j--) {
reverseWord = reverseWord + word.charAt(j);
}
return reverseWord;
}
Although, you should note that concatenating strings like that in a loop isn't great for performance, and using a StringBuilder would probably be faster (although with such a small application, it probably won't be noticeable):
public static String reverseWord(String word) {
StringBuilder reverseWord = new StringBuilder(word.length());
for (int j = word.length()-1; j >= 0; j--) {
reverseWord = reverseWord.append(word.charAt(j));
}
return reverseWord.toString();
}
Once you have that, you can split the input string (like you did), revere each word, and join them back together:
Scanner sc = new Scanner(System.in);
System.out.println("Enter a string to see it in reverse: ");
String userEntry = sc.nextLine();
String[] splitInput = userEntry.split(" ");
for (int i = 0; i < splitInput.length; i++) {
splitInput[i] = reverseWord(splitInput[i]);
}
System.out.println("Your sttring with words spelled backwards is " +
String.join(" ", splitInput));

All you need is to split your original sentence into separate words and use StringBuilder.reverse() to get words in reverse:
public static void main(String... args) {
String str = getSentenceFromConsole();
System.out.println("Your string with words spelled backwards is '" + reversLettersInWords(str) + '\'');
}
private static String getSentenceFromConsole() {
try (Scanner scan = new Scanner(System.in)) {
System.out.print("Enter a string to see it in reverse: ");
return scan.nextLine();
}
}
private static String reversLettersInWords(String str) {
return Arrays.stream(str.split("\\s+"))
.map(word -> new StringBuilder(word).reverse().toString())
.collect(Collectors.joining(" "));
}

i try with your code
Scanner sc = new Scanner(System.in);
System.out.println("Enter a string to see it in reverse: ");
String userEntry = sc.nextLine();
String[] splitInput = userEntry.split(" ");
StringBuilder sb = new StringBuilder();
for (int i = 0; i < splitInput.length; i++) {
String word = splitInput[i];
for (int j = word.length() - 1; j >= 0; j--) {
sb.append(word.charAt(j));
}
sb.append(" ");
}
System.out.println("Your sttring with words spelled backwards is " + sb.toString());
here i remove all access line of code....

String input = "i love you";
StringBuilder input1 = new StringBuilder();
input1.append(input);
input1 = input1.reverse();
System.out.println(input1);
You can use this implementation to try to reverse the string elements in the array.

how to combine or merge two strings in java? [duplicate]

This question already has answers here:
How do I concatenate two strings in Java?
(23 answers)
Closed 5 years ago.
Below is my code I'm expecting the output as "afbgchde" and not "abcdefgh" but ending up with out of index error, Hope there is a better way to get this..Please help..!!
String str1 = "abcde";
//char[] a = str1.toCharArray();
//System.out.println(a);
String str2 = "fgh";
char[] b = str2.toCharArray();
//System.out.println(b);
int i,j=0;
try
{
for(i=0;i<str1.length();i++)
{
char c = str1.charAt(i);
System.out.print(c);
if(j==i)
{
char d = str2.charAt(j);
System.out.print(d);
j++;
}
}
}
catch(Exception e)
{
System.out.println(e);
}

Simple:
char d = str2.charAt(j);
System.out.print(d);
j++;
You are accessing chars in your second string; but you never bother to check if j is still < str2.length().
Meaning: your for-loop for i contains that check; and prevents going beyond the length of str ... but then you forget to do that on your other string! So your merge only works when str and str2 happen to have the same size.
So a solution would more look like:
StringBuilder builder = new StringBuilder();
int j = 0;
for (int i=0; i < str.length(); i++) {
builder.append(str.charAt(i));
if (j < str2.length()) {
builder.append(str2.charAt(j));
j++;
}
}
// if str2 has more chars than str
if (j < str2.length()) {
// append ALL chars starting from index j
builder.append(str2.substring(j));
}
String merged = builder.toString();

Complete Code for your combiner.
public class StringCombiner {
public static void main(String[] args){
System.out.println(combine("Hello", "World"));
System.out.println(combine("He", "World"));
System.out.println(combine("Hello", "Wo"));
}
public static String combine(String str1, String str2){
StringBuilder output = new StringBuilder();
int i =0;
for(; i< str1.length(); ++i){
output.append(str1.charAt(i));
if(i < str2.length()){
output.append(str2.charAt(i));
}
}
if(i < str2.length()){
for(; i<str2.length(); ++i){
output.append(str2.charAt(i));
}
}
return output.toString();
}
}
Output:
HWeolrllod
HWeorld
HWeollo
Hope this helps.

Okay. Lets try this
String str1 = "abcde";
String str2 = "fgh";
int bigLength = str1.length()>str2.length()?str1.length():str2.length();
for(int i = 0; i<bigLength; i++){
if(i<str1.length())
System.out.print(str1.charAt(i))
if(i<str2.length())
System.out.print(str2.charAt(i))
}
Hope this will work for you.

just use StringBuilder class man
if you want to change a value of a String object
String class is an object that is unchangeable or can't be change when it is initialized
StringBuilder class is the best solution for any String that you want to have a change while the application is running
e.g. add a String or change value of a String or even shorten a String
that is the power of StringBuilder class
`

Removing all the characters from a given string

how can I modify my code so that it removes all the characters in a given string (not just a string) in another string in O(n)? If using other data structures would help, please hint as well.
public static String removeChar(String s, char ch){
StringBuilder sb= new StringBuilder();
char[] charArray= s.toCharArray();
for (int i=0; i<charArray.length; i++){
if (charArray[i]!=ch) {
sb.append(charArray[i]);
}
}
return sb.toString();
}
Is there a faster way for this?
UPDATE: I want to write a new function like removeAllCharsInSecondStringFromFirstString(String S1, String S2)

Rather then iterating each character of the String, you could use String.indexOf(int) and a loop to add each substring between ch intervals. Something like,
public static String removeChar(String s, char ch) {
StringBuilder sb = new StringBuilder();
int p1 = 0, p2 = s.indexOf(ch);
while (p2 > -1) {
sb.append(s.substring(p1, p2));
p1 = p2 + 1;
p2 = s.indexOf(ch, p1);
}
if (p1 < s.length()) {
sb.append(s.substring(p1, s.length()));
}
return sb.toString();
}

With hints and help of dimo I wrote this solution:
public static String removeAllChars(String src, String dst){
HashSet<Character> chars = new HashSet<>();
char[] dstCharArray=dst.toCharArray();
for (int i=0; i<dstCharArray.length; i++){
chars.add(dstCharArray[i]);
}
StringBuilder sb = new StringBuilder();
char[] srcCharArray = src.toCharArray();
for (int i=0; i<srcCharArray.length; i++){
if (!chars.contains(srcCharArray[i])){
sb.append(srcCharArray[i]);
}
}
return sb.toString();
}

If you really want to implement this yourself you can use a Set to contain the collection of characters that you want to strip out. Here's a template to get you started:
public static String removeAllChars(String source, String charsString) {
HashSet<Character> chars = new HashSet<>();
for (int i = 0; i < charsString.length(); i++) {
chars.add(charsString.charAt(i));
}
StringBuilder sb = new StringBuilder();
for (int i = 0; i < source.length(); i++) {
// chars.contains(source.charAt(i)) is O(1)
// use this to determine which chars to exclude
}
return sb.toString();
}

Try to use this.
Remove all no numerical value
String str = "343.dfsdgdffsggdfg333";
str = str.replaceAll("[^\\d.]", "");
Output will give you "343.333"
If in the future you will need delete numerical and special value try this
String str = "343.dfsdgdffsggdfg333";
string = string.replace(/[^a-zA-Z0-9]/g, '');

Static Method that takes integer array as parmeter and Return string

I want to create a static method Static String displayArray (int [] array) that takes an integer array as parameter, uses a loop to create and return a new String that represents the contents of the array surrounded by braces and separated by commas.
For example,
int [] myArray = { 12,9,10,25};
String str = displayArray(myArray);
System.out.println (str); // should display {12,9,10,25}
My solution:
public static String displayArray (int [] array) {
for (int i=0; i< array.length; i++) {
System.out.println(array[i]);
}
return null;
}
But it gives output as follows:
12
9
10
25
null

You need to build a String object to return. Right now you are returning null, which is literally nothing.
I'd suggest using a StringBuilder, it's a little faster than concatenating Strings directly. So before your loop you'll want to define a StringBuilder object and add the opening brace:
StringBuilder returnString = new StringBuilder();
returnString.append("{");
Then within your loop, you can concatenate each number:
returnString.append(Integer.toString(array[i]);
After that you'll want to make a check to see if you have the last element, if not, append a comma.
Finally append the closing brace, and instead of return null use:
return returnString.toString();

You might need this:
public static String displayArray(int[] array) {
StringBuilder builder = new StringBuilder("{");
for (int i = 0; i < array.length; i++) {
builder.append((array[i])).append(",");
}
return builder.substring(0, builder.length() - 1).concat("}");
}

Something like this:
public static String displayArray (int [] array) {
StringBuilder sb = new StringBuilder();
for (int i=0; i< array.length; i++) {
sb.append(array[i]);
if(i!=array.length-1)
sb.append(",");
}
return "{"+sb.toString()+"}";
}

Yes, exactly it is giving you the right output.
To get your desired output you can modify your display array function as follow:
public static String displayArray (int [] array) {
String str = "";
for (int i=0; i< array.length; i++) {
str += array[i]+",";
}
returns str;
}

public static String displayArray( int[] array )
{
return "{" + Arrays.toString( array ).replace("[", "").replace("]", "") + "}";
}
Going off of #BorisTheSpider idea and because I find this easier than Stringbuilder, here is your method to return the string { val1, val2, val3 }.
Basically, print out your braces manually and replace the brackets with "".

Do this instead:
public static String displayArray (int [] array) {
StringBuilder sb = new StringBuilder();
for (int i=0; i< array.length; i++) {
sb.append(array[i]+",");
}
String result=sb.toString()+",";
result=result.replace(",,","");
return "{"+result+"}";
}

None of the answers display the output like you wanted it.
public static String displayArray (int [] array) {
StringBuilder sb = new StringBuilder();
sb.append("{");
for (int i=0; i< array.length; i++) {
sb.append(array[i]);
if(i != array.length-1)
sb.append(",");
}
sb.append("}");
return sb.toString();
}

I want to split string without using split function?

I want to split string without using split . can anybody solve my problem I am tried but
I cannot find the exact logic.

Since this seems to be a task designed as coding practice, I'll only guide. No code for you, sir, though the logic and the code aren't that far separated.
You will need to loop through each character of the string, and determine whether or not the character is the delimiter (comma or semicolon, for instance). If not, add it to the last element of the array you plan to return. If it is the delimiter, create a new empty string as the array's last element to start feeding your characters into.

I'm going to assume that this is homework, so I will only give snippets as hints:
Finding indices of all occurrences of a given substring
Here's an example of using indexOf with the fromIndex parameter to find all occurrences of a substring within a larger string:
String text = "012ab567ab0123ab";
// finding all occurrences forward: Method #1
for (int i = text.indexOf("ab"); i != -1; i = text.indexOf("ab", i+1)) {
System.out.println(i);
} // prints "3", "8", "14"
// finding all occurrences forward: Method #2
for (int i = -1; (i = text.indexOf("ab", i+1)) != -1; ) {
System.out.println(i);
} // prints "3", "8", "14"
String API links
int indexOf(String, int fromIndex)
Returns the index within this string of the first occurrence of the specified substring, starting at the specified index. If no such occurrence exists, -1 is returned.
Related questions
Searching for one string in another string
Extracting substrings at given indices out of a string
This snippet extracts substring at given indices out of a string and puts them into a List<String>:
String text = "0123456789abcdefghij";
List<String> parts = new ArrayList<String>();
parts.add(text.substring(0, 5));
parts.add(text.substring(3, 7));
parts.add(text.substring(9, 13));
parts.add(text.substring(18, 20));
System.out.println(parts); // prints "[01234, 3456, 9abc, ij]"
String[] partsArray = parts.toArray(new String[0]);
Some key ideas:
Effective Java 2nd Edition, Item 25: Prefer lists to arrays
Works especially nicely if you don't know how many parts there'll be in advance
String API links
String substring(int beginIndex, int endIndex)
Returns a new string that is a substring of this string. The substring begins at the specified beginIndex and extends to the character at index endIndex - 1.
Related questions
Fill array with List data

You do now that most of the java standard libraries are open source
In this case you can start here

Use String tokenizer to split strings in Java without split:
import java.util.StringTokenizer;
public class tt {
public static void main(String a[]){
String s = "012ab567ab0123ab";
String delims = "ab ";
StringTokenizer st = new StringTokenizer(s, delims);
System.out.println("No of Token = " + st.countTokens());
while (st.hasMoreTokens()) {
System.out.println(st.nextToken());
}
}
}

This is the right answer
import java.util.StringTokenizer;
public class tt {
public static void main(String a[]){
String s = "012ab567ab0123ab";
String delims = "ab ";
StringTokenizer st = new StringTokenizer(s, delims);
System.out.println("No of Token = " + st.countTokens());
while (st.hasMoreTokens())
{
System.out.println(st.nextToken());
}
}
}

/**
* My method split without javas split.
* Return array with words after mySplit from two texts;
* Uses trim.
*/
public class NoJavaSplit {
public static void main(String[] args) {
String text1 = "Some text for example ";
String text2 = " Second sentences ";
System.out.println(Arrays.toString(mySplit(text1, text2)));
}
private static String [] mySplit(String text1, String text2) {
text1 = text1.trim() + " " + text2.trim() + " ";
char n = ' ';
int massValue = 0;
for (int i = 0; i < text1.length(); i++) {
if (text1.charAt(i) == n) {
massValue++;
}
}
String[] splitArray = new String[massValue];
for (int i = 0; i < splitArray.length; ) {
for (int j = 0; j < text1.length(); j++) {
if (text1.charAt(j) == n) {
splitArray[i] = text1.substring(0, j);
text1 = text1.substring(j + 1, text1.length());
j = 0;
i++;
}
}
return splitArray;
}
return null;
}
}

you can try, the way i did `{
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
String str = sc.nextLine();
for(int i = 0; i <str.length();i++) {
if(str.charAt(i)==' ') { // whenever it found space it'll create separate words from string
System.out.println();
continue;
}
System.out.print(str.charAt(i));
}
sc.close();
}`

The logic is: go through the whole string starting from first character and whenever you find a space copy the last part to a new string.. not that hard?

The way to go is to define the function you need first. In this case, it would probably be:
String[] split(String s, String separator)
The return type doesn't have to be an array. It can also be a list:
List<String> split(String s, String separator)
The code would then be roughly as follows:
start at the beginning
find the next occurence of the delimiter
the substring between the end of the previous delimiter and the start of the current delimiter is added to the result
continue with step 2 until you have reached the end of the string
There are many fine points that you need to consider:
What happens if the string starts or ends with the delimiter?
What if multiple delimiters appear next to each other?
What should be the result of splitting the empty string? (1 empty field or 0 fields)

You can do it using Java standard libraries.
Say the delimiter is : and
String s = "Harry:Potter"
int a = s.find(delimiter);
and then add
s.substring(start, a)
to a new String array.
Keep doing this till your start < string length
Should be enough I guess.

public class MySplit {
public static String[] mySplit(String text,String delemeter){
java.util.List<String> parts = new java.util.ArrayList<String>();
text+=delemeter;
for (int i = text.indexOf(delemeter), j=0; i != -1;) {
parts.add(text.substring(j,i));
j=i+delemeter.length();
i = text.indexOf(delemeter,j);
}
return parts.toArray(new String[0]);
}
public static void main(String[] args) {
String str="012ab567ab0123ab";
String delemeter="ab";
String result[]=mySplit(str,delemeter);
for(String s:result)
System.out.println(s);
}
}

public class WithoutSpit_method {
public static void main(String arg[])
{
char[]str;
String s="Computer_software_developer_gautam";
String s1[];
for(int i=0;i<s.length()-1;)
{
int lengh=s.indexOf("_",i);
if(lengh==-1)
{
lengh=s.length();
}
System.out.print(" "+s.substring(i,lengh));
i=lengh+1;
}
}
}
Result: Computer software developer gautam

Here is my way of doing with Scanner;
import java.util.Scanner;
public class spilt {
public static void main(String[] args)
{
Scanner input = new Scanner(System.in);
System.out.print("Enter the String to be Spilted : ");
String st = input.nextLine();
Scanner str = new Scanner(st);
while (str.hasNext())
{
System.out.println(str.next());
}
}
}
Hope it Helps!!!!!

public class StringWitoutPre {
public static void main(String[] args) {
String str = "md taufique reja";
int len = str.length();
char ch[] = str.toCharArray();
String tmp = " ";
boolean flag = false;
for (int i = 0; i < str.length(); i++) {
if (ch[i] != ' ') {
tmp = tmp + ch[i];
flag = false;
} else {
flag = true;
}
if (flag || i == len - 1) {
System.out.println(tmp);
tmp = " ";
}
}
}
}

In Java8 we can use Pattern and get the things done in more easy way. Here is the code.
package com.company;
import java.util.regex.Pattern;
public class umeshtest {
public static void main(String a[]) {
String ss = "I'm Testing and testing the new feature";
Pattern.compile(" ").splitAsStream(ss).forEach(s -> System.out.println(s));
}
}

static void splitString(String s, int index) {
char[] firstPart = new char[index];
char[] secondPart = new char[s.length() - index];
int j = 0;
for (int i = 0; i < s.length(); i++) {
if (i < index) {
firstPart[i] = s.charAt(i);
} else {
secondPart[j] = s.charAt(i);
if (j < s.length()-index) {
j++;
}
}
}
System.out.println(firstPart);
System.out.println(secondPart);
}

import java.util.Scanner;
public class Split {
static Scanner in = new Scanner(System.in);
static void printArray(String[] array){
for (int i = 0; i < array.length; i++) {
if(i!=array.length-1)
System.out.print(array[i]+",");
else
System.out.println(array[i]);
}
}
static String delimeterTrim(String str){
char ch = str.charAt(str.length()-1);
if(ch=='.'||ch=='!'||ch==';'){
str = str.substring(0,str.length()-1);
}
return str;
}
private static String [] mySplit(String text, char reg, boolean delimiterTrim) {
if(delimiterTrim){
text = delimeterTrim(text);
}
text = text.trim() + " ";
int massValue = 0;
for (int i = 0; i < text.length(); i++) {
if (text.charAt(i) == reg) {
massValue++;
}
}
String[] splitArray = new String[massValue];
for (int i = 0; i < splitArray.length; ) {
for (int j = 0; j < text.length(); j++) {
if (text.charAt(j) == reg) {
splitArray[i] = text.substring(0, j);
text = text.substring(j + 1, text.length());
j = 0;
i++;
}
}
return splitArray;
}
return null;
}
public static void main(String[] args) {
System.out.println("Enter the sentence :");
String text = in.nextLine();
//System.out.println("Enter the regex character :");
//char regex = in.next().charAt(0);
System.out.println("Do you want to trim the delimeter ?");
String delch = in.next();
boolean ch = false;
if(delch.equalsIgnoreCase("yes")){
ch = true;
}
System.out.println("Output String array is : ");
printArray(mySplit(text,' ',ch));
}
}

Split a string without using split()
static String[] splitAString(String abc, char splitWith){
char[] ch=abc.toCharArray();
String temp="";
int j=0,length=0,size=0;
for(int i=0;i<abc.length();i++){
if(splitWith==abc.charAt(i)){
size++;
}
}
String[] arr=new String[size+1];
for(int i=0;i<ch.length;i++){
if(length>j){
j++;
temp="";
}
if(splitWith==ch[i]){
length++;
}else{
temp +=Character.toString(ch[i]);
}
arr[j]=temp;
}
return arr;
}
public static void main(String[] args) {
String[] arr=splitAString("abc-efg-ijk", '-');
for(int i=0;i<arr.length;i++){
System.out.println(arr[i]);
}
}
}

You cant split with out using split(). Your only other option is to get the strings char indexes and and get sub strings.