Function Description
Java String class trim() method is used to remove the white space from the beginning and end of the string.
If String does not have any leading or trailing whitespaces it does not do anything and return the same string.
For example: If the string value is ” test “. It has leading and trailing white space. If we apply the trim() method on this string it will remove the white spaces from the beginning and end of the string and return the value “test”.
String str = ” test “;
System.out.println(str.trim());
Many times we see while comparing two strings, it returns false while the content of both the strings is the same. This issue comes because of leading or trailing whitespaces in the string. Even while we print the string on the console to check the issue it is untouched to figure out. But If we do a comparison after applying the trim() method we found the required result.
Method Signature
public String trim()
Parameter(s)
None
Return Type
It returns a string. If string has leading or trailing or trailing both whitespaces, it returns string after removing leading and trailing whitespaces. If the string does not have leading or trailing white space, it returns as it is.
Example of Java String Class trim() Method
public class ExampleStringTrim { public static void main(String[] args) { // creating string object leading with white space String strWithWhiteSpace = " Welcome to String trim Function learning "; System.out.println("String before removing white spaces : '" + strWithWhiteSpace + "'"); // return string after removing the starting and ending white spaces from String strAfterRemovingWhiteSpace = strWithWhiteSpace.trim(); System.out.println("String after removing white spaces : '" + strAfterRemovingWhiteSpace + "'"); // creating string object without white space String strWithoutWhiteSpace = "Welcome to String trim Function learning"; // comparing string with space and without space boolean areStringsEqual = strWithWhiteSpace.equals(strWithoutWhiteSpace); System.out.println("Comparing both strings equality without trim() method : " + areStringsEqual); // comparing two string with space and without space areStringsEqual = strWithWhiteSpace.trim().equals(strWithoutWhiteSpace.trim()); System.out.println("Comparing both strings equality with trim() method : " + areStringsEqual); } } Output: String before removing white spaces : ' Welcome to String trim Function learning ' String after removing white spaces : 'Welcome to String trim Function learning' Comparing both strings equality without trim() method : false Comparing both strings equality with trim() method : true
Other Methods of String Class
Sequence | Method | Description |
1 | char charAt(int index) | This method is used to return the character of the string at specified index. First character is at index 0 while last is at string length-1 . StringIndexOutOfBounds Exception is thrown if valid index value is not passed. |
2 | int length() | Returns the number of characters count in a string. |
3 | static String format(String format, Object… args) | Return the formatted String. It is a static method and formats the string as per passing format and argument(s). |
4 | static String format(Locale l, String format, Object… args) | Return the formatted String. It is a static method and formats the string as per passing format and argument(s) and locale. |
5 | String substring(int beginIndex) | Returns substring from the given index position to the end index of the string. |
6 | String substring(int beginIndex, int endIndex) | Returns substring from the specified begin index to the specified end index. |
7 | boolean contains(CharSequence s) | Returns boolean value(true/false). It searches the given sequence of characters within the string and returns true/false accordingly. Characters will be case sensitive while searching in string. |
8 | static String join(CharSequence delimiter, CharSequence… elements) | Returns joined string. This method joins each passing String using the specified delimiter. It is a static method. |
9 | static String join(CharSequence delimiter, Iterable<? extends CharSequence> elements) | Returns the joined string. This method joins each passing string object of an iterate object using the specified delimiter and returns the concatenated string. It is a static method. |
10 | boolean equals(Object another) | Returns boolean value(true/false). It checks the equality of string with the passing object. |
11 | boolean isEmpty() | Returns boolean value(true/false). It returns true if the string is empty otherwise returns false. |
12 | String concat(String str) | Returns the concatenating string. It concatenates the passing string at the end of the string. |
13 | String replace(char old, char new) | Return the replaced string. It replaces all occurrences of the specified character with the new character. |
14 | String replace(CharSequence old, CharSequence new) | Return the replaced string. It replaces all occurrences of the specified Character sequence with the specified new Character sequence. |
15 | String replaceAll(String regex, String replacement) | Returns the replaced string. It replaces all occurrences of the sequence of characters with the given replacement string that are matching with the given regular expression. |
16 | String replaceFirst(String regex, String replacement) | Returns the replaced string. It replaces the first matching sequence of characters with the replacement string that matches with the given regular expression. |
17 | static boolean equalsIgnoreCase(String another) | Returns the boolean (true/false) value. It compares the passing string with string by ignoring the case. It compares the content irrespective of lowercase or uppercase of the character(s). |
18 | String[] split(String regex) | Returns the array of strings resulting from splitting of the string around matches of the given regular expression. String is breaked into strings from all the matching regular expressions. |
19 | String[] split(String regex, int limit) | Returns the array of strings resulting from splitting of the string around matches of the given regular expression. It breaks the string from all the matching regular expression upto the given limit. |
20 | String intern() | Returns an interned string. This method helps to compare two objects using == operator and checks in a string constant pool. it is faster for comparison. |
21 | int indexOf(int ch) | Returns the index value of first occurrence of the specified character within the string |
22 | int indexOf(int ch, int fromIndex) | Returns the index value of first occurrence of the specified character from the substring starting from specified index |
23 | int indexOf(String substring) | Returns the index value of first occurrence of the specified substring within the string. |
24 | int indexOf(String substring, int fromIndex) | Returns the index value of the first occurrence of the specified string within the substring starting from specified index to end of the string index. |
25 | int lastIndexOf(int ch) | Returns the index value of last occurrence of the specified character |
26 | int lastIndexOf (int ch, int fromIndex) | Returns the index value of last occurrence of the specified character, search starts at given fromIndex. |
27 | int lastIndexOf (String str) | Returns the index value of last occurrence of the specified string. |
28 | int lastIndexOf (String str, int fromIndex | Returns the index value of last occurrence of the specified string, searches start from given fromIndex |
29 | String toLowerCase() | Returns all the characters of the string in lowercase . |
30 | String toLowerCase(Locale l) | Returns all the characters of the string in lowercase using specified locale. |
31 | String toUpperCase() | Returns all the characters of the string in uppercase. |
32 | String toUpperCase(Locale l) | Returns all the characters of the string in uppercase using specified locale. |
33 | static String valueOf(int value) | Return the converted string. It converts the objects and all primitive types of values into string. It is a static method. |
In this article, we learned all about the trim() method of String class with examples. Apart from the trim() method, we got an idea about other String methods too. We will come up with more articles explaining other String methods with examples. For more details please click on the respective methods link.
Great, thanks for sharing this blog. Much thanks again. Awesome. Aveline Anders Slemmer