Develop Reference

print Shortest sequence 1's in String

class Chotu
{
// Returns length of the longest subsequence of 1's
public static int ShortestSequence(String s) {
int count = 0;
int ans=s.length();
for(int i=0;i<s.length();i++)
{
if (s.charAt(i) == '1')
count++;
else
count = 0;
if(count < ans )
ans=count;
}
return ans;
}
// Driver code
public static void main(String[] args)
{
#SuppressWarnings("resource")
Scanner sc=new Scanner(System.in);
String s =sc.next();
if(ShortestSequence(s) > 1)
System.out.println(ShortestSequence(s));
else
System.out.println(-1);
}
}
I'm making program to find shortest sequence of 1's in user input string. I had made program which gives me longest sequence need help.
Input : 11100011001
Output : 1

You can split the String and then use stream:
public static String shortestSequence(String str) {
return Arrays.stream(str.split("[^1]"))
.filter(Predicate.not(String::isBlank))
.sorted(Comparator.comparing(String::length))
.findFirst().orElse("");
}
public static String longestSequence(String str) {
return Arrays.stream(str.split("[^1]"))
.filter(Predicate.not(String::isBlank))
.sorted(Comparator.comparing(String::length).reversed())
.findFirst().orElse("");
}
Then:
String str = "11100011001";
System.out.println("Shortest: " + shortestSequence(str));
System.out.println("Longest: " + longestSequence(str));
Output:
Shortest: 1
Longest: 111

Recursively reverse string Java

I tried to recursively reverse a string in Java, but I am getting just the last character as output.
I looked up online and most of the codes have modified the input string. I am trying to build the output from empty string to reversed string. Please tell me what is wrong in my program.
class reverseStringRecursion
{
public static void main(String args[])
{
System.out.println(reverse());
}
public static String reverse()
{
String strInput = " Hello I am my name.";
String output = "";
return recursiveHelper(strInput, 0, output);
}
public static String recursiveHelper(String strInput, int index, String output)
{
if(index == (strInput.length() - 1 ))
output += strInput.charAt(index) + "";
else
output+= recursiveHelper(strInput, index + 1, output) +"";
return output;
}
}
The above code is returning output '.' only and nothing else. PLease help.

Others have done a good job of explaining why your code doesn't work. For comparison, here's a working version with some comments:
public static void main(String args[])
{
System.out.println(reverse("Hello I am my name."));
}
public static String reverse(String text)
{
// Base case:
// If the string is empty, we're done.
if (text.length() == 0) {
return "";
} else {
// reverse("hello") = reverse("ello") + "h"
return reverse(text.substring(1)) + text.charAt(0);
}
}

Since String in Java are immuatable, passing it by parameter is useless on this case, so I removed it.
public class Main {
public static void main(String args[]) {
System.out.println(reverse());
}
public static String reverse() {
String strInput = " Hello I am my name.";
return recursiveHelper(strInput, 0);
}
public static String recursiveHelper(String strInput, int index) {
String output;
if(index == (strInput.length() - 1 )){
output = strInput.charAt(index) + "";
}else{
output = recursiveHelper(strInput, index + 1) + strInput.charAt(index);
}
return output;
}
}
Try it online!

Since strInput always contains the original String, the following condition makes sure your code only takes the last character of that String and ignore all the other characters:
if(index == (strInput.length() - 1 ))
output += strInput.charAt(index) + "";
To build the reversed String recursively, you have to append the last character of the String to the reverse of the sub-string of the first length()-1 characters.
This means that you don't need the 2nd and 3rd arguments of your method, and strInput should be passed a shorter String in each recursive call.
public static String reverse (String strInput)
{
if(strInput.length() <= 1)
return strInput;
else
return strInput.charAt(strInput.length()-1) + reverse (strInput.substring(0,strInput.length()-1));
}

I would change your function recursiveHelper() to only receive one argument (the String that you want to reverse). Using the substring method from Java you can do it like this:
public static String recursiveHelper(String strInput) {
if(strInput.length() == 1) {
return strInput;
}
else if(strInput == "") {
return "";
}
String subString1 = recursiveHelper(strInput.substring(0, strInput.length()/2)); // Here we copy the first half of the String to another String
String subString2 = recursiveHelper(strInput.substring(strInput.length()/2)); // Here we do the same, but with the second half of the original String
return susbString2 + subString1; // It is very important that you sum the two substrings in this order!
}

Modified your class:
public class ReverseStringRecursion {
public static void main(String args[])
{
System.out.println(reverse());
}
public static String reverse()
{
String strInput = "My Name is Jane Doe";
String output = "";
return recursiveHelper(strInput,0);
}
public static String recursiveHelper(String strInput, int index)
{
if(index == (strInput.length() - 1 ))
return "" + strInput.charAt(index) ;
else
return recursiveHelper(strInput,index+1) + strInput.charAt(index);
}
}

public class Main
{
public static void main(String[] args) {
String str1="abc";
String str2="";
for(int i=str1.length()-1;i>=0;i--)
{
str2=str2+Character.toString(str1.charAt(i));
}
System.out.println("After Reverse: "+str2);
}
}

1) Base case
if left>=right - do nothing
2) otherwise swap s[left] and s[right} and call helper(left+1, right-1)].
class Solution {
public void reverseString(char[] s) {
int left = 0, right = s.length - 1;
while (left < right) {
char tmp = s[left];
s[left++] = s[right];
s[right--] = tmp;
}
}
}

How to get individual letters in a string

I am so confused on how to search individual letters (specific vowels) within the the array of my string.
import static java.lang.System.*;
import java.util.Arrays;
public class Word {
private String word;
private static String vowels = "AEIOUaeiou"; //only one
public Word() {
String vow = "";
vowels = vow;
}
public Word(String wrd) {
word=wrd;
}
public void setWord(String wrd) {
}
public int getNumVowels(String[] ray, String vowels) {
int count=0;
for(String item : ray) {
if() {
count = count + 1;
}
}
return count;
}
public int getLength(String[] ray) {
return 0;
}
public String toString(String[] ray) {
return "";
}
}
This is the runner. How do I getNumVowels to work by searching for an individual letter by the input?
import java.util.Arrays;
import java.util.Scanner;
import static java.lang.System.*;
public class WordRunner {
public static void main(String[] args) {
String alpha="";
String [] ray = new String[4];
ray[0] ="Polo";
ray[1] ="Crazy";
ray[2] ="Abracadabra";
ray[3] ="Awesome";
out.println(Arrays.toString(ray));
out.println("Number of vowels: " + Arrays.getNumVowels(ray));
out.println("Length of the word: " + Arrays.getLength(ray));
}
}

There are several errors in your code...
You're calling Arrays methods which does not exists...
out.println("Number of vowels: "+ Arrays.getNumVowels(ray));
out.println("Length of the word: "+ Arrays.getLength(ray));
Modify Word class (you put a lot of innecessary stuff):
import static java.lang.System.*;
import java.util.Arrays;
public class Word
{
private static String vowels = "AEIOUaeiou"; //only one
public static int getNumVowels(String word)
{
int count=0;
for (int i=0; i < word.length(); i++)
{
// check if selected char is a vowel
if (vowels.contains(word.charAt(i) + ""))
{
count ++; // same as count = count + 1
}
}
return count;
}
}
Then to call the method, as it is static:
public static void main(String[] args)
{
System.out.println("Number of vowels of Polo: "+ Word.getNumVowels("Polo"));
//Output:
// Number of vowels of Polo: 2
// or execute like this:
String a = "Polo";
int vowels = Word.getNumVowels(a);
System.out.printlm("Number of vowels of Polo: "+ vowels);
//Output:
// Number of vowels of Polo: 2
}
UPDATE: if you want your word class count vowels in an array, simply use already existing method.
Inside Word class add an overload of the existing method that receives an array and use the old one:
// overload: same method name, but different arguments!!!
public static int getNumVowels(String[] array)
{
int count = 0;
for (i = 0; i < array.lenght; i ++){
// use existing method to save code!!
count += getNumVowels(array[i]);
}
return count;
}
And use it like:
String [] ray = new String[4];
ray[0] ="Polo";
ray[1] ="Crazy";
ray[2] ="Abracadabra";
ray[3] ="Awesome";
int vowels = Word.getNumVowels(ray); // count vowels in ALL array words...

You can get the char array from the string and loop over it looking for the required vowel (if you want to count how many times a single vowel appears, then there's no need to pass a string, you can simply use a char).
public int getNumVowels(String[] ray, char vowel) {
int count=0;
for(String s: ray)
{
char[] array = s.toLowerCase().toCharArray();
for (int i=0; i<array.length; i++) {
if(array[i] == vowel) {
count = count + 1;
}
}
}
return count;
}
You need the s.toLowerCase() only if you want the search to be case insensitive (because for example 'a' is different from 'A').

Straightforward way:
String vowels = "AEIOUaeiou";
int count = 0;
for (int i=0; i<str.length(); i++)
{
if (vowels.contains(str.charAt(i) + ""))
{
count++;
}
}
return count;

write a code to find the number of words in a string using methods

I've been looking and I can't find anywhere how to write a word count using 3 methods. Here is what the code looks like so far. I'm lost on how to use the methods. I can do this without using different methods and just using one. Please help!!!
public static void main(String[] args) {
Scanner in = new Scanner (System.in);
System.out.print("Enter a string: ");
String s = in.nextLine();
if (s.length() > 0)
{
getInputString(s);
}
else
{
System.out.println("ERROR - string must not be empty.");
System.out.print("Enter a string: ");
s = in.nextLine();
}
// Fill in the body with your code
}
// Given a Scanner, prompt the user for a String. If the user enters an empty
// String, report an error message and ask for a non-empty String. Return the
// String to the calling program.
private static String getInputString(String s) {
int count = getWordCount();
while (int i = 0; i < s.length(); i++)
{
if (s.charAt(i) == " ")
{
count ++;
}
}
getWordCount(count);
// Fill in the body
// NOTE: Do not declare a Scanner in the body of this method.
}
// Given a String return the number of words in the String. A word is a sequence of
// characters with no spaces. Write this method so that the function call:
// int count = getWordCount("The quick brown fox jumped");
// results in count having a value of 5. You will call this method from the main method.
// For this assignment you may assume that
// words will be separated by exactly one space.
private static int getWordCount(String input) {
// Fill in the body
}
}
EDIT:
I have changed the code to
private static String getInputString(String s) {
String words = getWordCount(s);
return words.length();
}
private static int getWordCount(String s) {
return s.split(" ");
}
But I can't get the string convert to integer.

You have read the name of the method, and look at the comments to decide what should be implemented inside the method, and the values it should return.
The getInputString method signature should be:
private static String getInputString(Scanner s) {
String inputString = "";
// read the input string from system in
// ....
return inputString;
}
The getWordCount method signature should be:
private static int getWordCount(String input) {
int wordCount = 0;
// count the number of words in the input String
// ...
return wordCount;
}
The main method should look something like this:
public static void main(String[] args) {
// instantiate the Scanner variable
// call the getInputString method to ... you guessed it ... get the input string
// call the getWordCount method to get the word count
// Display the word count
}

count=1 //last word must be counted
for(int i=0;i<s.length();i++)
{
ch=s.charAt(i);
if(ch==' ')
{
count++;
}
}

Use trim() and split() on 1-n whitespace chars:
private static int getWordCount(String s) {
return s.trim().split("\\s+").length;
}
The call to trim() is necessary, otherwise you'll get one extra "word" if there is leading spaces in the string.
The parameter "\\s+" is necessary to count multiple spaces as a single word separator. \s is the regex for "whitespace". + is regex for "1 or more".

What you need to do is, count the number of spaces in the string. That is the number of words in the string.
You will see your count will be off by 1, but after some pondering and bug hunting you will figure out why.
Happy learning!

You can do this by :
private static int getWordCount(String input) {
return input.split("\\s+").length;
}

Use String.split() method like :
String[] words = s.split("\\s+");
int wordCount = words.length;

I'm not sure what trouble you're having with methods but I dont think you need more than one, try this: it uses split to split up the words in a string, and you can chose the delimeters
String sentence = "This is a sentence.";
String[] words = sentence.split(" ");
for (String word : words) {
System.out.println(word);
}
then you can do:
numberOfWords = words.length();
if you want to use 3 methods, you can call a method from your main() method that does this for you, for example:
public String getInputString() {
Scanner in = new Scanner (System.in);
System.out.print("Enter a string: ");
String s = in.nextLine();
if (s.length() > 0) {
return s;
} else {
System.out.println("ERROR - string must not be empty.");
System.out.print("Enter a string: ");
return getInputString();
}
}
public int wordCount(String s) {
words = splitString(s)
return words.length();
}
public String[] splitString(String s) {
return s.split(" ");
}

Based on your code i think this is what you're trying to do:
private static int getWordCount(String input) {
int count = 0;
for (int i = 0; i < input.length(); i++) {
if (input.charAt(i) == ' ') {
count++;
}
}
return count;
}
Here's what I've done:
I've moved the code you were 'playing' with into the right method (getWordCount).
Corrected the loop you were trying to use (I think you have for and while loops confused)
Fixed your check for the space character (' ' not " ")
There is a bug in this code which you'll need to work out how to fix:
getWordCount("How are you"); will return 2 when it should be 3
getWordCount(""); will return 0
getWordCount("Hello"); will return 0 when it should be 1
Good luck!

Better use simple function of spilt() with arguments as space
int n= str.split(" ").length;

public static int Repeat_Words(String arg1,String arg2)
{
//It find number of words can be formed from a given string
if(arg1.length() < 1 || arg2.length() < 1)
return 0;
int no_words = 99999;
char[] str1 = arg1.toCharArray();
char[] str2 = arg2.toCharArray();
for(int x = 0; x < str1.length; x++)
{
int temp = 0;
for(int y = 0; y < str2.length; y++)
{
if(str1[x] == str2[y])
temp++;
}
if(temp == 0)
return 0;
if(no_words > temp)
no_words = temp;
temp = 0;
}
return no_words;
}

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.