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For more details, please go through - <a href="https://www.geeksforgeeks.org/dsa/basic-string-operations-with-implementation/">Basic String Operations with Implementation</a>

String Operations in Java

For more details, please go through - <a href="https://www.geeksforgeeks.org/java/java-string-methods/">Java String Methods</a>

String Operations.

In this video, we will see the Java Program to Check if Strings are Rotations of each other or not.&nbsp; Strings are defined as an array of characters. The difference between a character array and a string is the string is terminated with a special character ‘\0’.&nbsp; Rules for String Rotations:&nbsp; Rule 1: Number of characters in both the strings must be equal.&nbsp; Rule 2: All characters must be the same.&nbsp; Rule 3: Rotated around one of the characters. i.e str2 must be a substring of the str1 concatenated with str1.&nbsp; Algorithm:&nbsp; 1. First we create a temp string and store the concatenation of str1 to str1 in the temp string.i.e temp = str1.str1&nbsp; 2. If str2 is a substring of temp then str1 and str2 are rotations of each other.&nbsp; Example:&nbsp; str1 = "abcd"&nbsp; str2 = "efgh"&nbsp; temp = str1.str1 = "abcdabcd"&nbsp; str2 = bcda&nbsp; Output: Yes Since str2 is a substring of temp, str1 and str2 are rotations of each other.&nbsp; Here we use the string Concat method to check if Strings are Rotations of each other or not. Java Program to Check if strings are rotation of each other or not: <a href="https://www.geeksforgeeks.org/java-program-to-check-if-strings-are-rotations-of-each-other-or-not/">https://www.geeksforgeeks.org/java-program-to-check-if-strings-are-rotations-of-each-other-or-not/</a>

Java Program to Check if Strings are Rotations of each other or not

In this video, we will write a JAVA program return the maximum occurring character in an input string.For Example: Input String = GeeksforGeeks Output = e Input String = TEST Output = THere we use the “Hashing” method to return the maximum occurring character in an input string.Algorithm: Step 1: First we traverse through the string, we would hash each character into an array of ASCII characters.&nbsp; Step 2: Now we construct a character count array from the input string, and store the occurrence value. Step 3: Print the index of the maximum value in the count array.Example:&nbsp; Input = TEST Output = T Dry Run:&nbsp; count['T'] = 1 count['E’] = 1 count['S’'] = 1 count[‘T’]= 2ASCII characters are 256, so we use our Hash array size as 256. But if we know that our input string will have characters with values from 0 to 127 only, we can limit the Hash array size to 128. Similarly, based on extra info known about input string, the Hash array size can be limited to 26.Return maximum occurring character in input string: <a href="https://www.geeksforgeeks.org/return-maximum-occurring-character-in-the-input-string/">https://www.geeksforgeeks.org/return-maximum-occurring-character-in-the-input-string/</a>

Java Program to Return Maximum occurring Character in an Input String

In this video, we will write a Java Program to Check if Two Strings are Anagrams. What are anagrams? Anagrams are words or phrases you spell by rearranging the letters of another word or phrase. For examples: String 1: abac String 2: abca Output: TrueString 1: act String 2: cat Output: TrueHere in this video, we cover two different methods to check it:1. Using the Brute force method: Here we sort both strings and compare the sorted strings. Step 1: Make the character array of strings. Step 2: Sort both the character array. Step 3: Now check character array 1 and character array 2, if both are equal then print both strings are anagrams otherwise print false.2. Using Optimized Method:Step 1: In this method, two arrays are used. Step 2: Iterate through every character of both strings and increment the count of characters in the corresponding count arrays using for loop. Step 3: Compare count arrays. If both the count arrays are the same, then it returns true, otherwise, print false.Apart from that, we will see the time and space complexity of both mentioned methods i.e: For brute force method: Time complexity: O(n*logN) Space complexity: O(1)For Optimized method: Time complexity: O(n) Space complexity: O(n)

Java Program to Check if Two Strings are Anagrams

In this video, we will check whether the string contains only digits in Java.Example:1. Input: string = “7895668” &nbsp; &nbsp; Output: True &nbsp; &nbsp; Explanation: The given string contains only digits so the output is true.2. Input: string = “GeeksforGeeks2022” &nbsp; &nbsp;&nbsp;Output: false &nbsp; &nbsp;Explanation: The given string contains alphabet characters and digits so the output is false.Here we see three different types of methods for checking strings containing only digits in Java:<ol><li>Using traversal: Here we traverse each character of the input string. Then we check if the character of the string contains only digits from 0 to 9. If this condition is true then print “True” otherwise print “False”.</li><li>Using character.isDigit(Char Ch): This is an in-built function of Java. It simply checks whether each character of the string is a digit or not.</li><li>Using Regular Expression: In this method, we create a Regular Expression to check string contains only digits as mentioned below: regex = "[0-9]+"; Here we match the given string with a Regular Expression. In Java, this can be done by using Pattern. matcher(). It prints true if the string matches with the given regular expression, otherwise return false.</li></ol>How to check if string contains only digits in Java: <a href="https://www.geeksforgeeks.org/how-to-check-if-string-contains-only-digits-in-java/">https://www.geeksforgeeks.org/how-to-check-if-string-contains-only-digits-in-java/</a>

Java program to Check whether the String contains only digits

In this video, we will write a Java program for converting dates into strings. Examples: Input: date = “2022-8-24” Output: 2022-08-24 Here we see five methods to convert date to string in Java:<ol><li style="text-align:justify;">Using Simple Date format(): In this method, we use simple date format i.e Date Format df= New simpleDateFormat (“MM-DD-YYYY”).</li><li style="text-align:justify;">Using string class: In this method, we create an instance of SimpleDateFormat class to format the string representation of the date object. After that get the date using the Calendar object, and convert the given date into a string using format() method.</li><li style="text-align:justify;">Using Date Time Formatter: In this method we use Formatter for printing and parsing date-time objects.</li><li style="text-align:justify;">Using Time zone, Date Time Formatter: The ZonedDateTime class permits us to create a date/time object with a time zone. The default time zone will be used. So here we use the DateTimeFormatter class to display the time zone with date.</li><li style="text-align:justify;">Using Local Date Time: Here we get an instance of LocalDate from date. Then convert the given date into a string using the toString() method of LocalDate class.</li></ol>How to convert date to string in Java: <a href="https://www.geeksforgeeks.org/how-to-convert-date-to-string-in-java/">https://www.geeksforgeeks.org/how-to-convert-date-to-string-in-java/</a>

Java program to Convert Date to String

In this video, we will write a java program to to remove all white spaces from a String. Below are the approaches that we have used in this video: 1. Using .charAt() Method 2. Using .toCharArray() Method 3. Using .replaceAll() MethodMethod 1: In this method, we are iterating on each index of the String and getting the character present at the index using .charAt() method. If the character is not a space, then we are adding that character into a new result string.Method 2: In this method, we are using .toCharArray() to convert a String to an array of characters. Then we iterate on the character array and the characters that are not white spaces, we concat those characters into a new String variable.Method 3: In this method, we are using replaceAll() method of String and a regex to replace all white spaces from a string. We can either use \\s+ or \\s as a pattern to remove all white space characters, including tab characters. How to remove all white spaces from a String in Java? <a href="https://www.geeksforgeeks.org/how-to-remove-all-white-spaces-from-a-string-in-java/">https://www.geeksforgeeks.org/how-to-remove-all-white-spaces-from-a-string-in-java/</a>

Java Program to Remove all White Spaces from a String

In this video, we will learn the Java programs to remove the first and last character of a string.&nbsp; We see three different methods for removing the first and last character of a string in JAVA:&nbsp; 1. String.Substring(): The String.Substring() method returns a new string that is a substring of the original string.&nbsp; 2. StringBuilder deleteCharAt(): The deleteCharAt(int index) method of StringBuilder class remove the character at the given index from String contained by StringBuilder. This method takes the index as a parameter which represents the index of char we want to remove and returns the remaining String as StringBuilder Object. This StringBuilder is shortened by one char after the application of this method.&nbsp; 3. Stringbuffer.delete(): The java.lang.StringBuffer.delete() is an inbuilt method in Java that is used to remove or delete the characters in a substring of this sequence. The substring starts at a specified index start_point and extends to the character at the index end_point. Examples:&nbsp; 1. Input string = “GeeksforGeeks”&nbsp; Output string: eeksforGeek&nbsp; Here, the first character of the given string is ‘G’ and the last character of the given string is ‘s’. After removing the first and last character of a string, the string becomes “eeksForGeek”.&nbsp; 2. Input string = “Java Program”&nbsp; Output: ava Progra&nbsp; Here, the first character of the given string is ‘J’ and the last character of the given string is ‘m’. After removing the first and last character of a string, the string becomes “ava Progra”.&nbsp; Program to Remove First &amp; Last Character of a String: <a href="https://www.geeksforgeeks.org/remove-first-and-last-character-of-a-string-in-java/">https://www.geeksforgeeks.org/remove-first-and-last-character-of-a-string-in-java/</a>

Java Program to Remove First and Last Character of a String

In this video, we will see a JAVA program for Print all interleaving of given two strings.&nbsp; So basically an interleaved string of given two strings preserves the order of characters in individual strings. For example, in all the interleaving of above first example, ‘A’ comes before ‘B’ and ‘C’ comes before ‘D’.&nbsp; Examples:&nbsp; String 1: AB&nbsp; String 2: C &nbsp; Output:&nbsp; ABC ACB&nbsp; CAB&nbsp; So, C is said to be interleaving A and B , if it contains all and only characters of A and B order of all characters in individual strings is preserved.&nbsp; Input:&nbsp; str1 = "WX", str2 = "YZ"&nbsp; Output:&nbsp; WXYZ&nbsp; WYXZ&nbsp; WYZX&nbsp; YWXZ&nbsp; YWZX&nbsp; YZWX&nbsp; Here the time complexity is O(2 ^ (m+n)).&nbsp; Print all interleaving of given 2 strings: <a href="https://www.geeksforgeeks.org/print-all-interleavings-of-given-two-strings/">https://www.geeksforgeeks.org/print-all-interleavings-of-given-two-strings/</a>

Java Program to Print all Interleavings of given Two Strings

In this video, we will learn how to Concatenate two Strings in Java language.Examples: Input String 1: GEEKSFOR Input String 2: GEEKSOutput String: GEEKSFORGEEKSInput String 1 : HELLO Input String 2: WORLD!!Output : HELLO WORLD!!Here we see five different methods for string concatenation: 1. Using + operator 2. Using .concat() 3. Using StringBuilder Class 4. Using .format() 5. Using StringJoiner classWe will also look at some of the pros and cons of each method.The first way is using the + operator. This is a very simple way to concatenate two strings together and can be done with one line of code, but it does not allow for any formatting or trimming.Another way is using .concat( ) and the StringBuilder class, which allows for a lot more customization than just adding two strings together. It also has a lot more overhead than the other methods because it needs to create an object every time you use it.The third way is using .format(), which allows for formatting and trimming within your string and can be done with one line of code.The last method is StringJoiner class. It is a class in java.util package which is used to construct a sequence of characters(strings) separated by a delimiter and optionally starting with a supplied prefix and ending with a given suffix.Java String Concatenation: <a href="https://www.geeksforgeeks.org/java-string-concat-examples/">https://www.geeksforgeeks.org/java-string-concat-examples/</a> Merge two strings in Java: <a href="https://www.geeksforgeeks.org/alternatively-merge-two-strings-in-java/">https://www.geeksforgeeks.org/alternatively-merge-two-strings-in-java/</a>

Java Program to Concatenate Two Strings

Write a Java program to count the characters in each word in a given sentence? Examples:&nbsp; &nbsp;Input : geeks for geeks Output : geeks-&gt;5 for-&gt;3 geeks-&gt;5Approach:Here we have to find out number of words in a sentence and the corresponding character count of each word.&nbsp;<ul><li>Here first we create an equivalent char array of given String.</li><li>Now we iterate the char array using for loop. Inside for loop we declare a String with empty implementation.</li><li>Whenever we found an alphabet we will perform concatenation of that alphabet with the String variable and increment the value of i.</li><li>Now when i reaches to a space it will come out from the while loop and now String variable has the word which is previous of space.</li><li>Now we will print the String variable with the length of the String.</li></ul>&nbsp;Java program to count the characters in each word in a given sentence : <a href="https://www.geeksforgeeks.org/java-program-count-characters-word-given-sentence/">https://www.geeksforgeeks.org/java-program-count-characters-word-given-sentence/</a>

Java program to count the characters in each word in a given sentence

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