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Java Program To Remove All Leading and Trailing Whitespaces From The Given String.

In this tutorial, we will see how to remove all the leading and trailing whitespaces from the given String.

Introduction

We can remove all the leading and trailing spaces from the string in two ways,

  1. Using the regex expressions with String.replaceAll()
  2. Using the ready-made String.trim() method

1. Using the regex expressions with String.replaceAll()

We can use the following regex expressions to remove leading and trailing whitespaces from the given input string.

We are simply replacing all leading and trailing whitespaces with empty strings.

^\s+ - remove all leading whitespaces

\s+$ - remove all trailing whitespaces

Java program

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/**
 * A Java program to remove all the leading and trailing
 * whitespaces from the given string using the String.replaceAll() method.
 * By coderolls.com
 */
public class RemoveLeadingAndTrailingWhitespaces {

    public static void main(String[] args) {

        String exampleString = "     Let's learn Java   ";
        String result = "";

        System.out.println("(We are printing the example string in between the three hyphens" +
                " to show leading and trailing spaces)");
        System.out.println("\nThe example String is as given below: ");

        //We are printing the example string in between the three hyphens
        //to show leading and trailing spaces
        System.out.println("---" + exampleString + "---");

        //Removing all leading whitespace
        result = exampleString.replaceAll("^\\s+", "");

        // removing all trailing whitespace from stringWithoutLeadingOrTrailingSpaces
        result = result.replaceAll("\\s+$", "");

        System.out.println("\nThe example String after removing the leading and trailing spaces is as " +
                "given below: ");
        System.out.println("---" + result + "---");
    }
}

Output

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(We are printing the example string in between the three hyphens to show leading and trailing spaces)

The example String is given below: 
---     Let's learn Java   ---

The example String after removing the leading and trailing spaces is as given below: 
---Let's learn Java---

2. Using the ready-made String.trim() method

We can remove all the leading (at the start of the sting ) and trailing (at the end of the string) using the String.trim() method.

It is a simple way as compared to 1st way.

Here are using the ready-made method and we do not need to remember the regex expression to find all the leading and trailing spaces.

Java Program

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/**
 * A Java program to remove all the leading and trailing
 * whitespaces from the given string using the String.trim() method.
 * By coderolls.com
 */
public class TrimMethodExample {

    public static void main(String[] args) {
        String exampleString = "     Let's learn Java   ";

        System.out.println("(We are printing the example string in between the three hyphens to show " +
                "leading and trailing spaces)");
        System.out.println("\nThe example String is as given below: ");

        //We are printing the example string in between the three hyphens 
        //to show leading and trailing spaces
        System.out.println("---" + exampleString + "---");

        String result  = exampleString.trim();
        System.out.println("\nThe example String after removing the leading and trailing spaces is as " +
                "given below: ");
        System.out.println("---" + result + "---");
    }
}

Output

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(We are printing the example string in between the three hyphens to show leading and trailing spaces)

The example String is as given below: 
---     Let's learn Java   ---

The example String after removing the leading and trailing spaces is as given below: 
---Let's learn Java---

Conclusion

We can remove all the leading and trailing whitespaces from the given String as follows.

  1. replace all the leading and trailing whitespaces with an empty string 
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    result = exampleString.replaceAll("^\\s+", ""); // remove leading whitespaces
result = result.replaceAll("\\s+$", ""); // then removes trailing whitespaces
  2. Use the ready-made String.trim() method. 
    1

    String result  = exampleString.trim();

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