Java String trim()

The Java String class trim() method eliminates leading and trailing spaces. The Unicode value of space character is ‘u0020’. The trim() method in Java string checks this Unicode value before and after the string, if it exists then the method removes the spaces and returns the omitted string.

The string trim() method doesn’t omit middle spaces.

Signature

The signature or syntax of the String class trim() method is given below:

Returns

string with omitted leading and trailing spaces

Internal implementation

  public String trim() {            int len = value.length;            int st = 0;            char[] val = value;    /* avoid getfield opcode */                while ((st < len) && (val[st] <= ‘ ‘)) {                st++;            }            while ((st < len) && (val[len – 1] <= ‘ ‘)) {                len–;            }            return ((st > 0) || (len < value.length)) ? substring(st, len) : this;        }    

Java String trim() Method Example

FileName: StringTrimExample.java

  public class StringTrimExample{  public static void main(String args[]){  String s1=”  hello string   “;  System.out.println(s1+”tutoraspire”);//without trim()  System.out.println(s1.trim()+”tutoraspire”);//with trim()  }}  

Test it Now

Output

hello string TutorAspire hello stringtutoraspire

Java String trim() Method Example 2

The example demonstrates the use of the trim() method. This method removes all the trailing spaces so the length of the string also reduces. Let’s see an example.

FileName: StringTrimExample2.java

  public class StringTrimExample2 {        public static void main(String[] args) {            String s1 =”  hello java string   “;            System.out.println(s1.length());            System.out.println(s1); //Without trim()            String tr = s1.trim();            System.out.println(tr.length());            System.out.println(tr); //With trim()        }    }    

Output

22    hello java string     17  hello java string

Java String trim() Method Example 3

The trim() can be used to check whether the string only contains white spaces or not. The following example shows the same.

FileName: TrimExample3.java

  public class TrimExample3  {  // main method  public static void main(String argvs[])  {    String str = ” abc “;    if((str.trim()).length() > 0)  {  System.out.println(“The string contains characters other than white spaces n”);  }  else  {  System.out.println(“The string contains only white spaces n”);     }    str = ”    “;    if((str.trim()).length() > 0)  {  System.out.println(“The string contains characters other than white spaces n”);  }  else  {  System.out.println(“The string contains only white spaces n”);     }    }  }  

Output

The string contains characters other than white spaces     The string contains only white spaces

Java String trim() Method Example 4

Since strings in Java are immutable; therefore, when the trim() method manipulates the string by trimming the whitespaces, it returns a new string. If the manipulation is not done by the trim() method, then the reference of the same string is returned. Observe the following example.

FileName: TrimExample4.java

  public class TrimExample4  {  // main method  public static void main(String argvs[])  {    // the string contains white spaces  // therefore, trimming the spaces leads to the  // generation of new string  String str = ” abc “;    // str1 stores a new string   String str1 = str.trim();    // the hashcode of str and str1 is different  System.out.println(str.hashCode());  System.out.println(str1.hashCode() + “n”);    // no white space present in the string s  // therefore, the reference of the s is returned   // when the trim() method is invoked  String s = “xyz”;  String s1 = s.trim();    // the hashcode of s and s1 is the same  System.out.println(s.hashCode());  System.out.println(s1.hashCode());    }  }  

Output

The string contains characters other than white spaces     The string contains only white spaces

Next TopicJava String valueOf()

Java String trim() method

Java String trim()

The string trim() method doesn’t omit middle spaces.

Signature

Returns

Internal implementation

Java String trim() Method Example

Java String trim() Method Example 2

Java String trim() Method Example 3

Java String trim() Method Example 4

Scatter | Gather | Vectored IO

C# Implicitly Typed Local Variable

You may also like