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Java Programming Exercises

Java String: Exercises, Practice, Solution

Java String Exercises [100 exercises with solution]

1. Write a Java program to get the character at the given index within the String. Go to the editor

Sample Output:

Original String = Java Exercises!                                                                             
The character at position 0 is J                                                                              
The character at position 10 is i 

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2. Write a Java program to get the character (Unicode code point) at the given index within the String. Go to the editor

Sample Output:

Original String : w3resource.com                                                                              
Character(unicode point) = 51                                                                                 
Character(unicode point) = 101 

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3. Write a Java program to get the character (Unicode code point) before the specified index within the String. Go to the editor

Sample Output:

Original String : w3resource.com                                                                              
Character(unicode point) = 119                                                                                
Character(unicode point) = 99

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4. Write a java program to count a number of Unicode code points in the specified text range of a String. Go to the editor

Sample Output:

Original String : w3rsource.com                                                                               
Codepoint count = 9

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5. Write a java program to compare two strings lexicographically. Go to the editor

Sample Output:

String 1: This is Exercise 1                                                                                  
String 2: This is Exercise 2                                                                                  
"This is Exercise 1" is less than "This is Exercise 2" 

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6. Write a java program to compare two strings lexicographically, ignoring case differences. Go to the editor

Sample Output:

String 1: This is exercise 1                                                                                  
String 2: This is Exercise 1                                                                                  
"This is exercise 1" is equal to "This is Exercise 1"

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7. Write a Java program to concatenate a given string to the end of another string. Go to the editor

Sample Output:

String 1: PHP Exercises and                                                                                   
String 2: Python Exercises                                                                                    
The concatenated string: PHP Exercises and Python Exercises

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8. Write a Java program to test if a given string contains the specified sequence of char values. Go to the editor

Sample Output:

Original String: PHP Exercises and Python Exercises                                                           
Specified sequence of char values: and                                                                        
true 

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9. Write a Java program to compare a given string to the specified character sequence. Go to the editor

Sample Output:

Comparing example.com and example.com: true                                                                   
Comparing Example.com and example.com: false

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10. Write a Java program to compare a given string to the specified string buffer. Go to the editor

Sample Output:

Comparing example.com and example.com: true                                                                   
Comparing Example.com and example.com: false 

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11. Write a Java program to create a new String object with the contents of a character array. Go to the editor

Sample Output:

The book contains 234 pages.

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12. Write a Java program to check whether a given string ends with the contents of another string. Go to the editor

Sample Output:

"Python Exercises" ends with "se"? false                                                                      
"Python Exercise" ends with "se"? true

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13. Write a Java program to check whether two String objects contain the same data. Go to the editor

Sample Output:

"Stephen Edwin King" equals "Walter Winchell"? false                                                          
"Stephen Edwin King" equals "Mike Royko"? false

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14. Write a Java program to compare a given string to another string, ignoring case considerations. Go to the editor

Sample Output:

"Stephen Edwin King" equals "Walter Winchell"? false                                                          
"Stephen Edwin King" equals "stephen edwin king"? true 

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15. Write a java program to print current date and time in the specified format. Go to the editor

Sample Output:

Current Date and Time :                                                                                       
June 19, 2017                                                                                                 
3:13 pm 
N.B. : The current date and time will change according to your system date and time.

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16. Write a Java program to get the contents of a given string as a byte array. Go to the editor

Sample Output:

The new String equals This is a sample String.

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17. Write a Java program to get the contents of a given string as a character array. Go to the editor

Sample Output:

The char array equals "[[email protected]"

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18. Write a Java program to create a unique identifier of a given string. Go to the editor

Sample Output:

The hash for Python Exercises. is 863132599 

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19. Write a Java program to get the index of all the characters of the alphabet. Go to the editor

Sample Output:

a  b c  d e  f  g h i  j                                                                                     
=========================                                                                                     
36 10 7 40 2 16 42 1 6 20                                                                                     
                                                                                                   
k  l  m  n  o  p q  r  s  t                                                                                   
===========================                                                                                   
8 35 22 14 12 23 4 11 24 31                                                                                   

u  v  w  x  y  z                                                                                              
================                                                                                              
5 27 13 18 38 37

Sample string of all alphabet: "The quick brown fox jumps over the lazy dog."

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20. Write a Java program to get the canonical representation of the string object. Go to the editor

Sample Output:

str1 == str2? false                                                                                           
str1 == str3? true

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21. Write a Java program to get the last index of a string within a string. Go to the editor

Sample Output:

 a  b c  d  e  f  g  h i  j                                                                                   
===========================                                                                                   
36 10 7 40 33 16 42 32 6 20                                                                                   
                                                                                                              
k  l  m  n  o  p q  r  s  t                                                                                   
===========================                                                                                   
8 35 22 14 41 23 4 29 24 31                                                                                   
                                                                                                              
 u  v  w  x  y  z                                                                                             
=================                                                                                             
21 27 13 18 38 37

Sample string of all alphabet: "The quick brown fox jumps over the lazy dog."

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22. Write a java program to get the length of a given string. Go to the editor

Sample Output:

The string length of 'example.com' is: 11

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23. Write a Java program to find whether a region in the current string matches a region in another string. Go to the editor

Sample Output:

str1[0 - 7] == str2[28 - 35]? true                                                                            
str1[9 - 15] == str2[9 - 15]? false 

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24. Write a Java program to replace all the 'd' characters with 'f' characters. Go to the editor

Sample Output:

Original string: The quick brown fox jumps over the lazy dog.                                                 
New String: The quick brown fox jumps over the lazy fog.

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25. Write a Java program to replace each substring of a given string that matches the given regular expression with the given replacement. Go to the editor

Sample string : "The quick brown fox jumps over the lazy dog."

In the above string replace all the fox with cat.

Sample Output:

Original string: The quick brown fox jumps over the lazy dog.                                                 
New String: The quick brown cat jumps over the lazy dog.         

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26. Write a Java program to check whether a given string starts with the contents of another string. Go to the editor

Sample Output:

Red is favorite color. starts with Red? true                                                                  
Orange is also my favorite color. starts with Red? false

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27. Write a Java program to get a substring of a given string between two specified positions. Go to the editor

Sample Output:

old = The quick brown fox jumps over the lazy dog.                                                            
new = brown fox jumps

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28. Write a Java program to create a character array containing the contents of a string. Go to the editor

Sample Output:

Java Exercises.

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29. Write a Java program to convert all the characters in a string to lowercase. Go to the editor

Sample Output:

Original String: The Quick BroWn FoX!                                                                         
String in lowercase: the quick brown fox!

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30. Write a Java program to convert all the characters in a string to uppercase. Go to the editor

Sample Output:

Original String: The Quick BroWn FoX!                                                                         
String in uppercase: THE QUICK BROWN FOX!  

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31. Write a Java program to trim any leading or trailing whitespace from a given string. Go to the editor

Sample Output:

Original String:  Java Exercises                                                                              
New String: Java Exercises

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32. Write a Java program to find longest Palindromic Substring within a string. Go to the editor

Sample Output:

The given string is: thequickbrownfoxxofnworbquickthe
The longest palindrome substring in the giv
en string is; brownfoxxofnworb
The length of the palindromic substring is: 16

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33. Write a Java program to find all interleavings of given strings. Go to the editor

Sample Output:

The given strings are: WX  YZ
The interleavings strings are: 
YWZX
WYZX
YWXZ
WXYZ
YZWX
WYXZ

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34. Write a Java program to find the second most frequent character in a given string. Go to the editor

Sample Output:

The given string is: successes
The second most frequent char in the string is: c

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35. Write a Java program to print all permutations of a given string with repetition. Go to the editor

Sample Output:

The given string is: PQR
The permuted strings are:
PPP
PPQ
PPR
...
RRP
RRQ
RRR

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36. Write a Java program to check whether two strings are interliving of a given string. Assuming that the unique characters in both strings. Go to the editor

Sample Output:

The given string is: PMQNO
The interleaving strings are MNO and PQ
The given string is interleaving: true

The given string is: PNQMO
The interleaving strings are MNO and PQ
The given string is interleaving: false

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37. Write a Java program to find Length of the longest substring without repeating characters. Go to the editor

Sample Output:

Input String : pickoutthelongestsubstring
The longest substring : [u, b, s, t, r, i, n, g]
The longest Substring Length : 8

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38. Write a Java program to print after removing duplicates from a given string. Go to the editor

Sample Output:

The given string is: w3resource
After removing duplicates characters the new string is: w3resouc

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39. Write a Java program to find first non repeating character in a string. Go to the editor

Sample Output:

The given string is: gibblegabbler
The first non repeated character in String is: i

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40. Write a Java program to divide a string in n equal parts. Go to the editor

Sample Output:

The given string is: abcdefghijklmnopqrstuvwxy
The string divided into 5 parts and they are: 

abcde
fghij
klmno
pqrst
uvwxy

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41. Write a Java program to remove duplicate characters from a given string presents in another given string. Go to the editor

Sample Output:

The given string is: the quick brown fox
The given mask string is: queen

The new string is: 
th ick brow fox

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42. Write a Java program to print list items containing all characters of a given word. Go to the editor

Sample Output:

The given strings are: rabbit   bribe   dog   
The given word is: bib 

The strings containing all the letters of the given word are: 
rabbit
bribe

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43. Write a Java program to find the maximum occurring character in a string. Go to the editor

Sample Output:

The given string is: test string
Max occurring character in the given string is: t

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44. Write a Java program to reverse a string using recursion. Go to the editor

Sample Output:

The given string is: The quick brown fox jumps
The string in reverse order is:
spmuj xof nworb kciuq ehT

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45. Write a Java program to reverse words in a given string. Go to the editor

Sample Output:

The given string is: Reverse words in a given string
The new string after reversed the words: string given a in words Reverse

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46. Write a Java program to reverse every word in a string using methods. Go to the editor

Sample Output:

The given string is: This is a test string
The string reversed word by word is: 
sihT si a tset gnirts

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47. Write a Java program to rearrange a string so that all same characters become d distance away. Go to the editor

Sample Output:

The given string is: accessories
The string after arrange newly is: 
secrsecisao

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48. Write a Java program to remove "b" and "ac" from a given string. Go to the editor

Sample Output:

The given string is: abrambabasc
After removing the new string is: aramaasc

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49. Write a Java program to find first non-repeating character from a stream of characters. Go to the editor

Sample Output:

String: godisgood
Reading: g
The first non-repeating character so far is:  g
Reading: o
The first non-repeating character so far is:  g
Reading: d
The first non-repeating character so far is:  g
Reading: i
The first non-repeating character so far is:  g
Reading: s
The first non-repeating character so far is:  g
Reading: g
The first non-repeating character so far is:  o
Reading: o
The first non-repeating character so far is:  d
Reading: o
The first non-repeating character so far is:  d
Reading: d
The first non-repeating character so far is:  i

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50. Write a Java program to find lexicographic rank of a given string. Go to the editor

Sample Output:

The Given String is: BDCA
The Lexicographic rank of the given string is: 12

N.B.: Total possible permutations of BDCA are(lexicographic order) :
ABCD ABDC ACBD ACDB ADBC ADCB BACD BADC BCAD BCDA BDAC BDCA
1   2   3   4   5   6   7   8   9   10   11   12
The BDCA appear in 12 position of permutation (lexicographic order).

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51. Write a Java program to count and print all the duplicates in the input string. Go to the editor

Sample Output:

The given string is: w3resource
The duplicate characters and counts are: 
e  appears  2  times
r  appears  2  times

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52. Write a Java program to check if two given strings are rotations of each other. Go to the editor

Sample Output:

The given strings are: ABACD  and  CDABA

The concatination of 1st string twice is: ABACDABACD
The 2nd string CDABA  exists in the new string.

Strings are rotations of each other

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53. Write a Java program to match two strings where one string contains wildcard characters. Go to the editor

Sample Output:

The given string is: abcdhgh
The given pattern string is: abc*d?*
The given pattern is matching.

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54. Write a Java program to find the smallest window in a string containing all characters of another string. Go to the editor

Sample Output:

The given string is: welcome to w3resource
Characters to find in the main sring are: tower
The smallest window which contains the finding characters is : to w3re

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55. Write a Java program to remove all adjacent duplicates recursively from a given string. Go to the editor

Sample Output:

The given string is: aabaarbarccrabmq
The new string after removing all adjacent duplicates is:
brmq

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56. Write a Java program to append two given strings such that, if the concatenation creates a double characters then omit one of the characters. Go to the editor

Sample Output:

The given strings are: food  and  door
The string after concatination are: foodoor

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57. Write a Java program to return a new string where the last two characters of a given string, if present, are swapped. Go to the editor

Sample Output:

The given strings is: string
The string after swap last two characters are: strign

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58. Write a Java program to read a string and return true if it ends in "ng". Go to the editor

Sample Output:

The given strings is: string
The string containing ng at last: true

The given strings is: strign
The string containing ng at last: false

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59. Write a Java program to read a string,if the string begins with "red" or "black" return that color string, otherwise return the empty string. Go to the editor

Sample Output:

The given strings is: blacksea
The string begins with the color: black

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60. Write a Java program to read two strings append them together and return the result. If the strings are different lengths, omit chars from the beginning of longer string and make them equal length. Go to the editor

Sample Output:

The given strings is: Welcome and home
The new string is: comehome

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61. Write a Java program to read a string and an int n, return a string made of the first and last n characters from the string. Go to the editor

Sample Output:

The given strings is: Welcome
The given numbers is: 3
The new string is: Welome

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62. Write a Java program to read a string and return true if "good" appears starting at index 0 or 1 in the given string.Go to the editor

Sample Output:

The given strings is: goodboy
The 'good' appear in the string is: true

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63. Write a Java program to return true from a given string if the first two characters in the string also appear at the end. Go to the editor

Sample Output:

The given strings is: educated
The first two characters appear in the last is: true

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64. Write a Java program to read a string and if a substring of length two appears at both its beginning and end, return a string without the substring at the beginning otherwise, return the original string unchanged. Go to the editor

Sample Output:

The given strings is: educated
The new string is: ucated

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65. Write a Java program to read a string and if the first or last characters are 't', return the string without those 't' otherwise return the string unchanged. Go to the editor

Sample Output:

The given strings is: testcricket
The new string is: estcricke

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66. Write a Java program to read a string and return the string without the first two characters.Except keep the first char if it is 'g' and keep the second char if it is 'h'. Go to the editor

Sample Output:

The given strings is: goat
The new string is: gat

he given strings is: photo
The new string is: hoto

The given strings is: ghost
The new string is: ghost

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67. Write a Java program to read a string and if one or both of the first tow characters is 'x', return without those 'x',otherwise return the string unchanged. Go to the editor

Sample Output:

The given strings is: oocyte
The new string is: cyte

The given strings is: boat
The new string is: bat

The given strings is: own
The new string is: wn

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68. Write a Java program to read a string and returns after remove the # and its immediate left and right characters. Go to the editor

Sample Output:

The given strings is: test#string
The new string is: testring

The given strings is: test##string
The new string is: testring

The given strings is: test#the#string
The new string is: teshtring

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69. Write a Java program to return the substring that is between the first and last appearance of the substring 'toast' in the given string,or return the empty string if substirng 'toast' does not exists. Go to the editor

Sample Output:

The given strings is: sweettoastbuttertoast
The new string is: butter

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70. Write a Java program to check whether a string is pq-balanced or not.A String is pq-balanced if for all the p's in the string atleast one 'q' must exists right of the p's.But 'q' before the 'p' makes the pq-balanced false. Go to the editor

Sample Output:

The given strings is: gfpmpnppqab
The string is pq-balanced? true

The given strings is: gfpmpnpqpab
The string is pq-balanced? false

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71. Write a Java program to return true when either of the two given strings appear at the end of the other string ignoring case sensitivity. Go to the editor

Sample Output:

The given strings are: xyz  and pqrxyz
Is one string appears at the end of other? true

The given strings are: pqrxyz  and xyz
Is one string appears at the end of other? true

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72. Write a Java program to return true if a given string contain the string 'pop', but the middle 'o' also may other character. Go to the editor

Sample Output:

The given string is: dikchapop
Is p?p appear in the given string? true

The given string is: dikp$pdik
Is p?p appear in the given string? true

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73. Write a Java program to return true if the given string contains an appearance of 'abc' but not directly a period(.) and followed by. Go to the editor

Sample Output:

The given strings is: testabc.test
Is 'abc' appear before period? true

The given string is: test.abctest
Is 'abc' appear before period? false

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74. Write a Java program to return whether a prefix string made of the first N specific characters of the string appear somewhere else in the string. Go to the editor

Sample Output:

The given strings is: MrsJemsmrsam
The prefix string length is: 3
Is 'Mrs' appear else where in the string? false

The given string is: MrsJemsMrsam
The prefix string length is: 3
Is 'Mrs' appear else where in the string? true

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75. Write a Java program to check whether a string 'abc' in the middle of a given string. Here middle means the number of character to the left and right of the substring 'abc' must differ by at most one. Go to the editor

Sample Output:

The given string is: xxxabcxxxxx
Is abc appear in middle? false

The given string is: xxabcxxx
Is abc appear in middle? true

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76. Write a Java program to count how many times the substring 'life' present at anywhere in a given string. Counting can also happen for the substring 'li?e', any character instead of 'f'. Go to the editor

Sample Output:

The given string is: liveonwildlife
The substring life or li?e appear number of times: 2

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77. Write a Java program to add a string with specific number of times seperated by a substring. Go to the editor

Sample Output:

The given strings are: try  and  best
Number to times to be repeat: 3
The new string is: trybesttrybesttry

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78. Write a Java program to repeat a specific number of characters for specific number of times from the last of a string. Go to the editor

Sample Output:

The given string is: string
The new string after repetition: inginging

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79. Write a Java program to return the given string after removing the 2nd character from the substring of length three, starting with 'z' and ending with 'g'. Go to the editor

Sample Output:

The given string is: kitandkatcaketoket
The new string is: ktandktcaktokt

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80. Write a Java program to check whether the character immediately before and after of # is same in a given string. Go to the editor

Sample Output:

The given string is: moon#night
The before and after character are same: true

The given string is: bat##ball
The before and after character are same: false

The given string is: #moon#night
The before and after character are same: true

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81. Write a Java program to check whether the string 'red' and 'blue' appear in same number of times in a given string. Go to the editor

Sample Output:

The given string is: bigbatfatman
The appearance of red and blue are same: true

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82. Write a Java program to repeat every character twice in the original string. Go to the editor

Sample Output:

The given string is: welcome
The new string is: wweellccoommee

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83. Write a Java program to make a new string from two given string in such a way that, each character of two string will come respectively. Go to the editor

Sample Output:

The given strings  are: welcome  and  w3resource
The new string is: wwe3lrceosmoeurce

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84. Write a Java program to make a new string made of p number of characters from the first of a given string and followed by p-1 number characters till the p is greater than zero. Go to the editor

Sample Output:

The given string is: welcome
Number of repetition characters and repetition: 4
The new string is: welcwelwew

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85. Write a Java program to make a new string with each character of just before and after of t-string whichever it appears in m-string. Assume that m-string and non-empty t-string has given. Go to the editor

Sample Output:

The given string are: weablcoabmeab  and ab
The new string is: elome

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86. Write a Java program to return the number of triples in the given string. A triple is a character appearing three times in a row in a string. Go to the editor

Sample Output:

The given string is: welllcommmmeee
The number of triples in the string is: 4

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87. Write a Java program to check whether a z is happy or not. A 'z' is happy when there is another 'z' immediately to its left or right.Return true if all the z's in the given string are happy. Go to the editor

Sample Output:

The given string is: azzlea
Is z happy in the string: true

The given string is: azmzlea
Is z happy in the string: falses

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88. Write a Java program to return a string where every appearance of the lowercase word 'is' has been replaced with 'is not'. Go to the editor

Sample Output:

The given string is: it is a string
The new string is: it is not a string

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89. Write a Java program to return the sum of the numbers (may form more than one digits), appearing in the string. Go to the editor

Sample Output:

The given string is: it 15 is25 a 20string
The sum of numbers in the string is: 60

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90. Write a Java program to return true if the number of appearances of 'the' and 'is' anywhere in the string is equal. Go to the editor

Sample Output:

The given string is: Thisisthethesis
Are the appearance of 'the' and 'is' equal? false

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91. Write a Java program to count the number of words ending in 'm' or 'n' (not case sensitive). Go to the editor

Sample Output:

The given string is: mam is in the room
The number of words ends eith m or n is: 3

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92. Write a Java program to return a substring after removing the all instances of remove string as given from the given main string. Go to the editor

Sample Output:

The main string is: This is the test string
The removable string is: st
The new string is: This is the te ring

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93. Write a Java program to find the longest substring appears at both ends of a given string. Go to the editor

Sample Output:

The given string is: playersplay
The longest substring in the string is: play

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94. Write a Java program to find the longest mirror image string at the both ends of a given string. Go to the editor

Sample Output:

The given string is: rotavator
The longest mirror image string in the string is: rotavator

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95. Write a Java program to return the sum of the digits present in the given string. If there is no digits the sum return is 0. Go to the editor

Sample Output:

The given string is: ab5c2d4ef12s
The sum of the digits in the string is: 14

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96. Write a Java program to return the string after removing all 'z' (except the very first and last) from a given string. Go to the editor

Sample Output:

The given string is: zebrazone
The new string is: zebraone

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97. Write a Java program to return a string with the characters of the index position 0,1,2, 5,6,7, ... from a given string. Go to the editor

Sample Output:

The given string is: w3resource.com
The new string is: w3rour.co

Click me to see the solution

98. Write a Java program to return the number of index positions from two given strings where they contain the same substring of two characters.Go to the editor

Sample Output:

The given strings are: aabxyyz  and aabuyyz
The sum of the digits in the string is: 4

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99. Write a Java program to check whether the first instance of 'z' is immediately followed by another 'z' in a given string. Go to the editor

Sample Output:

The given string is: fizzez
Is 'z' appear twice respectively? true

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100. Write a Java program to return a new string using every characters of even positions from a given string. Go to the editor

Sample Output:

The given string is: w3resource.com
The new string is: wrsuc.o

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New Exercises:R Programming