How do I align string print out in left, right, center alignment?

The following code snippet will teach you how to align string in left, right or center alignment when you want to print out string to a console. We will print the string using the printf(String format, Object... args) method. The format specifier / parameter defines how the string will be formatted for output and the args is the value that will be formatted.

The format parameter / specifier include flags, width, precision and conversion-characters in the order shown below. The square brackets in the notation means the part is an optional parameter.

% [flags] [width] [.precision] conversion-character
Flags Description
- left-align the output, when not specified the default is to right-align
+ print (+) or (-) sign for numeric value
0 zero padded a numeric value
, comma grouping separator for number greater that 1000
space will output a (-) symbol for negative value and a space if positive
Conversion Description
s string, use capital S to uppercase the strings
c character, use capital C to uppercase the characters
d integer: byte, short, integer, long
f floating point number: float, double
n new line

Width: Defines the field width for printing out the value of argument. It also represents the minimum number of characters to
be printed out to the output.

Precision: For floating-point conversion the precision define the number of digits of precision in a floating point value. For string value this will extract the substring.

To center the string for output we use the StringUtils.center() method from the Apache Commons Lang library. This method will center-align the string str in a larger string of size using the default space character (‘ ‘). You can supply the third parameter to define your own space character / string.

package org.kodejava.example.lang;

import org.apache.commons.lang3.StringUtils;

import java.time.LocalDate;
import java.time.Month;
import java.time.temporal.ChronoUnit;

public class StringAlignment {
    private static Object[][] people = {
        {"Alice", LocalDate.of(2000, Month.JANUARY, 1)},
        {"Bob", LocalDate.of(1989, Month.DECEMBER, 15)},
        {"Carol", LocalDate.of(1992, Month.JULY, 24)},
        {"Ted", LocalDate.of(2006, Month.MARCH, 13)},
    };

    public static void main(String[] args) {
        String nameFormat = "| %1$-20s | ";
        String dateFormat = " %2$tb %2$td, %2$tY  | ";
        String ageFormat = " %3$3s |%n";
        String format = nameFormat.concat(dateFormat).concat(ageFormat);
        String line = new String(new char[48]).replace('\0', '-');

        System.out.println(line);
        System.out.printf("|%s|%s|%s|%n",
            StringUtils.center("Name", 22),
            StringUtils.center("Birth Date", 16),
            StringUtils.center("Age", 6));
        System.out.println(line);

        for (Object[] data : people) {
            System.out.printf(format,
                data[0], data[1],
                ChronoUnit.YEARS.between((LocalDate) data[1], LocalDate.now()));
        }

        System.out.println(line);
    }
}

Here is the output of our code snippet above:

------------------------------------------------
|         Name         |   Birth Date   | Age  |
------------------------------------------------
| Alice                |  Jan 01, 2000  |   17 |
| Bob                  |  Dec 15, 1989  |   27 |
| Carol                |  Jul 24, 1992  |   24 |
| Ted                  |  Mar 13, 2006  |   10 |
------------------------------------------------

Maven Dependencies

<!-- http://repo1.maven.org/maven2/org/apache/commons/commons-lang3/3.6/commons-lang3-3.6.jar -->
<dependency>
    <groupId>org.apache.commons</groupId>
    <artifactId>commons-lang3</artifactId>
    <version>3.6</version>
</dependency>

How do I find text between two strings?

In this example we’ll use the StringUtils.substringBetween() method. Here we’ll extract the title and body of our HTML document. Let’s see the code.

package org.kodejava.example.commons.lang;

import java.util.Date;
import org.apache.commons.lang.StringUtils;

public class NestedString {
    public static void main(String[] args) {
        String helloHtml = "<html>" +
                "<head>" +
                "   <title>Hello World from Java</title>" +
                "<body>" +
                "Hello, today is: " + new Date() +
                "</body>" +
                "</html>";

        String title = StringUtils.substringBetween(helloHtml, "<title>", "</title>");
        String content = StringUtils.substringBetween(helloHtml, "<body>", "</body>");

        System.out.println("title = " + title);
        System.out.println("content = " + content);
    }
}

By print out the title and content we’ll see something similar to:

title = Hello World from Java
content = Hello, today is: Tue Apr 08 07:02:39 ICT 2008

How do I count word occurrences in a string?

package org.kodejava.example.commons.lang;

import org.apache.commons.lang.StringUtils;

public class WordCountDemo {
    public static void main(String[] args) {
        // We have the source text we'll do the search on.
        String source = "From the download page, you can download the Java " +
            "Tutorials for browsing offline. Or you can just download " +
            "the examples.";
        // The word we want to count its occurrences
        String word = "you";

        // Using StringUtils.countMatches() method we can count the occurrences
        // frequency of a word/letter in the giver source of string.
        int wordFound = StringUtils.countMatches(source, word);

        // Print how many we have found the word
        System.out.println(wordFound + " occurrences of the word '" + word +
            "' was found in the text.");
    }
}

Here is the result of the code above.

2 occurrences of the word 'you' was found in the text.

Maven Dependencies

<!-- http://repo1.maven.org/maven2/commons-lang/commons-lang/2.6/commons-lang-2.6.jar -->
<dependency>
    <groupId>commons-lang</groupId>
    <artifactId>commons-lang</artifactId>
    <version>2.6</version>
</dependency>