Print a Table in Java

1. Using printf()/println() to Print a List as a Table in Java
2. Using System.out.format() to Print a List as a Table in Java

To print any information in a tabular structure in Java, we can use the printf() or format() method of the class java.io.PrintStream.

Using printf()/println() to Print a List as a Table in Java

The printf(format, arguments) method provides String formatting. We can specify the rules for formatting using format patterns and the rules start with %.

Here we have a POJO class Student with basic attributes like id, name, age and grade and the TestExample class where we create a List of students and print that information in a tabular format.

The formatting string consists of literals and format specifiers, which include flags, width, precision, and conversion character in this sequence. For example %[flags][width][.precision]conversion-charcater. Specifiers given in the bracket are optional. The printf internally uses java.util.Formatter to parse the format string and output it.

The conversion-character determines how the string is formatted. Here we have used two of the common ones, s, d, and c. The s formats strings while d formats decimal integers, and the result of c is a Unicode Character. Hence, in this code, we have used a combination of width and conversion-character to format the given student’s data into a table.

The method printf("%10s %20s %5s %5s", "STUDENT ID", "NAME", "AGE", "GRADE") has the format specifier to format the arguments passed. Thus, %10s, for example, formats a string with a specified number of characters and also right justify it. The println() method moves the cursor to the next line after printing the result.

The method format("%10s %20s %5d %5c",student.getId(), student.getName(), student.getAge(), student.getGrade()) also has the format specifier and getter methods of the student class to get the value of the attributes.

import java.util.ArrayList;
import java.util.List;

public class TableExample {
    public static void main (String args[]){
        List<Student> students = new ArrayList<>();
        students.add(new Student("S101","John",8, '4'));
        students.add(new Student("S102","Leo",10, '6'));
        students.add(new Student("S103","Mary",5, '2'));
        students.add(new Student("S104","Lisa",6, '3'));

        System.out.println("-----------------------------------------------------------------------------");
        System.out.printf("%10s %20s %5s %5s", "STUDENT ID", "NAME", "AGE", "GRADE");
        System.out.println();
        System.out.println("-----------------------------------------------------------------------------");
        for(Student student: students){
            System.out.format("%10s %20s %5d %5c",
                    student.getId(), student.getName(), student.getAge(), student.getGrade());
            System.out.println();
        }
        System.out.println("-----------------------------------------------------------------------------");
    }
}
class Student{
    private String id;
    private String name;
    private int age;
    private Character grade;
    Student(String id,String name,int age, Character grade){
        this.id = id;
        this.name = name;
        this.age = age;
        this.grade = grade;
    }

    public String getId() {
        return id;
    }

    public Character getGrade() {
        return grade;
    }

    public String getName() {
        return name;
    }

    public int getAge() {
        return age;
    }
}

Output:

-----------------------------------------------------------------------------
STUDENT ID                 NAME   AGE GRADE
-----------------------------------------------------------------------------
      S101                 John     8     4
      S102                  Leo    10     6
      S103                 Mary     5     2
      S104                 Lisa     6     3
-----------------------------------------------------------------------------

Using System.out.format() to Print a List as a Table in Java

The java.io package provides the PrintStream class with two methods used to replace print and println. These methods are format() and printf() and are equivalent. In format(String format, Object... args), the format specifies the formatting to be used, args, which are the list of arguments to be printed using this formatting.

Here, we create a 2D array of String data type; the 4 rows and columns are not specified at this point. It simply means that we are declaring an array of 4 arrays. Then, we initialize each row with a String object.

We run a for loop for each row inside the table, a multidimensional array of arrays. For each row, we format the row using System.out.format() specifying the formatting pattern for each row.

Here %15s means right-justified string with 15 widths, and %n is a platform-specific line separator.

public class Test1 {
    public static void main (String args[]){
        String[][] table = new String[4][];
        table[0] = new String[] { "Apple", "Banana", "Papaya" };
        table[1] = new String[] { "Chicken", "Mutton", "Fish" };
        table[2] = new String[] { "Carrots", "Beans", "Cabbage" };
        table[3] = new String[] { "Candy", "Cake", "Bread" };

        for (String[] row : table) {
            System.out.format("%15s %15s %15s %n", row);
        }
    }
}

Output:

  Apple         Banana         Papaya
Chicken         Mutton           Fish
Carrots          Beans        Cabbage
  Candy           Cake          Bread