Introduction
In Java, we can format strings depending on our needs and get the required output. The printf command is very useful in Java. The printf command takes text as a string and formats it depending on the instructions given to it.
String Formatting
| "%s" |
Format a string with the required number of characters. |
| "%10s" |
Format a string with the specified number of characters and also right justify. |
| "%-10s" |
Format a string with the specified number of characters and also left justify. |
For formatting numbers we use the "d" character and for floating point numbers we use the "f" character.
Example
package demo;
public class Demo
{
public static void main(String args[])
{
String n = "NAME";
System.out.printf("%10s %n",n);
}
}
Output
![string formatting right justify]()
Example
package demo;
public class Demo
{
public static void main(String args[])
{
String n = "NAME";
String l = "LOCATION";
System.out.printf("%-10s %10s %n",n, l);
}
}
Output
![string formatting left justify]()
Integer Formatting
| "%d" |
Format a string with the required numbers. |
| "%5d" |
Format a string with the required number of integers and also pad with spaces to the left side if integers are not adequate. |
| "%05d" |
Format a string with the required number of integers and also pad with zeroes to the left if integers are not adequate. |
Example
package demo;
public class Demo
{
public static void main(String args[])
{
String r = "ROLL NO";
int i = 12345;
System.out.printf("%s %15d %n", r, i);
}
}
Output
![integer formatting]()
Example
package demo;
public class Demo
{
public static void main(String args[])
{
int r = 54321;
int i = 12345;
System.out.printf("%015d %15d %n", r, i);
}
}
Output
![integer formatting with zeroes]()
Floating Point Number Formatting
| "%f" |
Format a string with the required numbers. It will always give six decimal places. |
| "%.3f" |
Format a string with the required numbers. It gives three decimal places. |
| "%12.3f" |
Format a string with the required numbers. The string occupies twelve characters. If numbers are not adequate then spaces are used on the left side of the numbers. |
Example
package demo;
public class Demo
{
public static void main(String args[])
{
System.out.printf("%.3f %n", 123.45789);
}
}
Output
![floating point no. formatting]()
Example
package demo;
public class Demo
{
public static void main(String args[])
{
System.out.printf("%12.3f %n", 123.45789);
}
}
Output
![floating point no. formatting with spaces]()
Summary
This article explains string formatting in Java and the use of the printf command in Java.