New String APIs/Methods in Java 11 (JDK11) with Examples

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Java 11 added a few useful APIs to the commonly used String class. In this tutorial, we will explore and use these new APIs with an example.

Check out Java String class API guide at https://www.javaguides.net/2018/08/java-string-class-api-guide.html.

Here are the APIs/methods added to String class in Java 11:

• String java.lang.String.repeat(int count) - As the name suggests, the repeat() instance method repeats the string content.
• String java.lang.String.strip() - The strip() instance method returns a string with all leading and trailing whitespaces removed.
• String java.lang.String.stripLeading() - This method returns a string with all leading white space removed.
• String java.lang.String.stripTrailing() - This method returns a string with all trailing white space removed.
• boolean java.lang.String.isBlank() - The isBlank() instance method returns true if the string is empty or contains only whitespace. Otherwise, it returns false.
• Stream java.lang.String.lines() - The lines() instance method returns a Stream of lines extracted from the string, separated by line terminators.

Let's see the usage of all the above new String APIs with an example.

Video Tutorial

This tutorial explained in below YouTube video:

repeat() API

As the name suggests, the repeat() instance method repeats the string content.

It returns a string whose value is the concatenation of the string repeated n times, where n is passed as a parameter:

package net.javaguides.examples;

/**
 * Java 11 (JDK11) New String APIs/Methods with Examples
 * @author Ramesh Fadatare
 *
 */
public class StringAPIInJDK11 {
    public static void main(String[] args) {

        String input = "Java";
        /**
         *  the repeat() instance method repeats the string content
         */
        String output = input.repeat(2) + "Guides".repeat(3);
        System.out.println(output); // Output: JavaJavaGuidesGuidesGuides
    }
}

Output:

JavaJavaGuidesGuidesGuides

strip(), stripLeading() and stripTrailing() methods

• String java.lang.String.strip() - The strip() instance method returns a string with all leading and trailing whitespaces removed.
• String java.lang.String.stripLeading() - This method returns a string with all leading white space removed.
• String java.lang.String.stripTrailing() - This method returns a string with all trailing white space removed.

package net.javaguides.examples;

/**
 * Java 11 (JDK11) New String APIs/Methods with Examples
 * @author Ramesh Fadatare
 *
 */
public class StringAPIInJDK11 {
    public static void main(String[] args) {

        String input1 = "\n\t  hello   \u2005";

        /**
         *  The strip() instance method returns a string
         *  with all leading and trailing whitespaces removed 
         */
        String output1 = input1.strip();
        System.out.println(output1);

        // stripLeading() usage
        System.out.println(input1.stripLeading());

        // stripTrailing() usage
        System.out.println(input1.stripTrailing());
    }
}

Output:

hello
hello   ?

   hello

isBlank() API

The isBlank() String class method returns true if the string is empty or contains only whitespace. Otherwise, it returns false:

package net.javaguides.examples;
/**
 * Java 11 (JDK11) New String APIs/Methods with Examples
 * @author Ramesh Fadatare
 *
 */
public class StringAPIInJDK11 {
    public static void main(String[] args) {

        String input = "\n\t\u2005 ";

        /**
         * The isBlank() instance method returns true if the string is empty or contains
         * only whitespace. Otherwise, it returns false
         */
        boolean result = input.isBlank();
        System.out.println(result);
    }
}

Output:

true

lines() API

The lines() String class method returns a Stream of lines extracted from the string, separated by line terminators:

package net.javaguides.examples;

import java.util.stream.Stream;

/**
 * Java 11 (JDK11) New String APIs/Methods with Examples
 * 
 * @author Ramesh Fadatare
 *
 */
public class StringAPIInJDK11 {
    public static void main(String[] args) {
        /**
         * The lines() instance method returns a Stream of lines extracted from the
         * string, separated by line terminators
         */
        String multilineStr = "This is\n a multiline\n string.";

        Stream < String > stream = multilineStr.lines();
        stream.forEach(action - > System.out.println(action));

        long lineCount = multilineStr.lines().count();
        System.out.println(lineCount);
    }
}

Output:

This is
 a multiline
 string.
3

A line terminator is one of the following: “\n”, “\r”, or “\r\n”.

The stream contains lines in the order in which they occur. The line terminator is removed from each line.

Conclusion

In this quick article, we explored the new String APIs in Java 11 with an example.

Check out the Java String class API guide at https://www.javaguides.net/2018/08/java-string-class-api-guide.html.

References

• https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/lang/String.html