Java 11 String enhancements with examples

Posted On December 9, 2020December 23, 2020

Java 11 has made some significant improvements to the String class. In this article, we will be exploring the Java 11 String enhancements

strip

Java 11 has added a new strip method to the String class. This method removes all the leading and trailing whitespaces in a String. Consider the following code:

String input = "   Hello   World   ";
System.out.println(input);
String output = input.strip();
System.out.println(output);

This code produces the following output:

Hello World
Hello World

In addition to strip, the String class also has a trim method which also removes all leading and trailing whitespaces. This method exists right from the early versions of Java and so has some limitations. Earlier, the ASCII character set was used. So, trim can only remove whitespaces represented by ASCII characters. However, later on Java adopted the Unicode character set.  Unicode has some additional characters that represent whitespace. The trim method cannot remove these whitespaces. So, the strip method was added to overcome this limitation.

For example consider the following code:

String input = " Hello ";
System.out.println("Strip output:" + input.strip());
System.out.println("Trim output:" + input.trim());

input = '\u2001' + "Hello" + '\u2001';
System.out.println("Strip output:" + input.strip());
System.out.println("Trim output:" + input.trim());

This code produces the following output:

Strip output:Hello
Trim output:Hello
Strip output:Hello
Trim output:?Hello?

stripLeading

The stripLeading method removes all the leading whitespaces in a String. The following code demonstrates this method:

 String input = " Hello World ";
System.out.println(input);
String output = input.stripLeading();
System.out.println(output);

This code produces the following output:

    Hello World     
Hello World

stripTrailing

The stripTrailing method removes all the trailing whitespaces in a String. The following code demonstrates this method:

String input = " Hello World ";
System.out.println(input);
String output = input.stripTrailing();
System.out.println(output);

This code produces the following output:

    Hello World 
    Hello World

isBlank

The isBlank method checks if the String is empty or contains only whitespaces and returns a boolean value accordingly. The following code demonstrates this method:

String input = "";
System.out.println("input.isBlank:"+input.isBlank());
input=" ";
System.out.println("input.isBlank:"+input.isBlank());
input = " Hello World ";
System.out.println("input.isBlank:"+input.isBlank());

This code produces the following output:

input.isBlank:true
input.isBlank:true
input.isBlank:false

The String class also has a isEmpty method. While the isBlank method returns true if the String is empty or contains only whitespaces, the isEmpty method returns true only if the String is empty that is its length is 0.

Consider the following code:

String input = "";
System.out.println("input.isBlank:" + input.isBlank());
input = " ";
System.out.println("input.isBlank:" + input.isBlank());
input = " Hello World ";
System.out.println("input.isBlank:" + input.isBlank());

This code produces the following output:

input.isBlank:true
input.isEmpty:true
input.isBlank:true
input.isEmpty:false

lines

The lines method returns a Stream of String values which are separated by line terminators like \n, \r or \n\r. The following code demonstrates this method:

 String input = "I am line 1.\nI am line 2. \rI am line 3.";
Stream<String> lines = input.lines();
lines.forEach(str -> System.out.println(str));

This code uses the Java 8 forEach method to iterate over the Stream . It produces the following output:

I am line 1.
I am line 2. 
I am line 3.

If the input String does not have any line terminator characters, it simply returns a Stream having the input String. So consider the following code:

String input = "I am line 1.I am line 2. I am line 3.";
Stream<String> lines = input.lines();
lines.forEach(str -> System.out.println(str));

This code produces the following output:

I am line 1.I am line 2. I am line 3.

repeat

The repeat method accepts as parameter an int value and creates a String that consists of the input String repeated the specified number of times. The following code demonstrates this method:

 String input = "Hello ";
String output = input.repeat(3);
System.out.println(output);

This code produces the following output:

Hello Hello Hello

If the input String is empty or if you specify 0 as the input parameter, then this method returns an empty String. So consider the following code:

 String input = "Hello ";
System.out.println("Output:"+input.repeat(0));
input = "";
System.out.println("Output:"+input.repeat(2));

This code produces the following output:

Output:
Output:

Conclusion

So, in this article, we saw some of the Java 11 String enhancements. We took a look at the strip, stripLeading, stripTrailing, isBlank, lines and repeat methods