El Classe Java String trim() El mètode elimina els espais inicials i finals. El valor Unicode del caràcter espai és 'u0020'. El mètode trim() a la cadena Java comprova aquest valor Unicode abans i després de la cadena; si existeix, el mètode elimina els espais i retorna la cadena omesa.

El mètode string trim() no omet espais mitjans.

Signatura

La signatura o sintaxi del mètode String class trim() es mostra a continuació:

 public String trim() 

Devolucions

cadena amb espais inicials i finals omesos

Implementació interna

 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] 0) || (len value.length)) ? substring(st, : this; pre> <h2>Java String trim() Method Example</h2> <p> <strong>FileName:</strong> StringTrimExample.java</p> <pre> public class StringTrimExample{ public static void main(String args[]){ String s1=&apos; hello string &apos;; System.out.println(s1+&apos;javatpoint&apos;);//without trim() System.out.println(s1.trim()+&apos;javatpoint&apos;);//with trim() }} </pre> <span> Test it Now </span> <p> <strong>Output</strong> </p> <pre> hello string javatpoint hello stringjavatpoint </pre> <h2>Java String trim() Method Example 2</h2> <p>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&apos;s see an example.</p> <p> <strong>FileName:</strong> StringTrimExample2.java</p> <pre> public class StringTrimExample2 { public static void main(String[] args) { String s1 =&apos; hello java string &apos;; 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() } } </pre> <p> <strong>Output</strong> </p> <pre> 22 hello java string 17 hello java string </pre> <h2>Java String trim() Method Example 3</h2> <p>The trim() can be used to check whether the string only contains white spaces or not. The following example shows the same.</p> <p> <strong>FileName:</strong> TrimExample3.java</p> <pre> public class TrimExample3 { // main method public static void main(String argvs[]) { String str = &apos; abc &apos;; if((str.trim()).length() &gt; 0) { System.out.println(&apos;The string contains characters other than white spaces 
&apos;); } else { System.out.println(&apos;The string contains only white spaces 
&apos;); } str = &apos; &apos;; if((str.trim()).length() &gt; 0) { System.out.println(&apos;The string contains characters other than white spaces 
&apos;); } else { System.out.println(&apos;The string contains only white spaces 
&apos;); } } } </pre> <p> <strong>Output</strong> </p> <pre> The string contains characters other than white spaces The string contains only white spaces </pre> <h2>Java String trim() Method Example 4</h2> <p>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.</p> <p> <strong>FileName:</strong> TrimExample4.java</p> <pre> 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 = &apos; abc &apos;; // 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() + &apos;
&apos;); // no white space present in the string s // therefore, the reference of the s is returned // when the trim() method is invoked String s = &apos;xyz&apos;; String s1 = s.trim(); // the hashcode of s and s1 is the same System.out.println(s.hashCode()); System.out.println(s1.hashCode()); } } </pre> <p> <strong>Output</strong> </p> <pre> The string contains characters other than white spaces The string contains only white spaces </pre> <hr></len)>

Sortida

 hello string javatpoint hello stringjavatpoint 

Mètode Java String trim() Exemple 2

L'exemple mostra l'ús del mètode trim(). Aquest mètode elimina tots els espais al final de manera que la longitud de la cadena també es redueix. Vegem un exemple.

Nom de l'arxiu: 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() } } 

Sortida

 22 hello java string 17 hello java string 

Mètode Java String trim() Exemple 3

El trim() es pot utilitzar per comprovar si la cadena només conté espais en blanc o no. L'exemple següent mostra el mateix.

Nom de l'arxiu: 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 
'); } else { System.out.println('The string contains only white spaces 
'); } str = ' '; if((str.trim()).length() > 0) { System.out.println('The string contains characters other than white spaces 
'); } else { System.out.println('The string contains only white spaces 
'); } } } 

Sortida

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

Mètode Java String trim() Exemple 4

Com que les cadenes en Java són immutables; per tant, quan el mètode trim() manipula la cadena retallant els espais en blanc, retorna una cadena nova. Si la manipulació no es fa amb el mètode trim(), llavors es retorna la referència de la mateixa cadena. Observeu l'exemple següent.

Nom de l'arxiu: 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() + '
'); // 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()); } } 

Sortida

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