Java/Development Class/printf

Align float numbers

 
public class Main {
  public static void main(String[] argv) throws Exception {
    for (double i = 1.0; i < 20.0; i++)
      System.out.printf("%10.2f %10.2f %10.2f\n", i, Math.sqrt(i), i * i);
  }
}
/*    1.00       1.00       1.00
      2.00       1.41       4.00
      3.00       1.73       9.00
      4.00       2.00      16.00
      5.00       2.24      25.00
      6.00       2.45      36.00
      7.00       2.65      49.00
      8.00       2.83      64.00
      9.00       3.00      81.00
     10.00       3.16     100.00
     11.00       3.32     121.00
     12.00       3.46     144.00
     13.00       3.61     169.00
     14.00       3.74     196.00
     15.00       3.87     225.00
     16.00       4.00     256.00
     17.00       4.12     289.00
     18.00       4.24     324.00
     19.00       4.36     361.00
*/

Align string output

 
public class Main {
  public static void main(String[] argv) throws Exception {
    System.out.printf("%10s %10s %10s\n", "this", "is", "a test");
  }
}

Basic Math with System.out.printf

 
/*
 * Copyright (c) 1995 - 2008 Sun Microsystems, Inc.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 *   - Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 *
 *   - Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in the
 *     documentation and/or other materials provided with the distribution.
 *
 *   - Neither the name of Sun Microsystems nor the names of its
 *     contributors may be used to endorse or promote products derived
 *     from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
 * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
public class BasicMathDemo {
  public static void main(String[] args) {
    double a = -191.635;
    double b = 43.74;
    int c = 16, d = 45;
    System.out.printf("The absolute value of %.3f is %.3f%n", a, Math.abs(a));
    System.out.printf("The ceiling of %.2f is %.0f%n", b, Math.ceil(b));
    System.out.printf("The floor of %.2f is %.0f%n", b, Math.floor(b));
    System.out.printf("The rint of %.2f is %.0f%n", b, Math.rint(b));
    System.out.printf("The max of %d and %d is %d%n", c, d, Math.max(c, d));
    System.out.printf("The min of of %d and %d is %d%n", c, d, Math.min(c, d));
  }
}

"%d %(d %+d %05d

  
public class MainClass{
  public static void main(String args[]) {
    System.out.printf("%d %(d %+d %05d\n", 3, -3, 3, 3);

  }
}
//3 (3) +3 00003

Default floating-point format: %f

  
public class MainClass{
  public static void main(String args[]) {
    System.out.printf("Default floating-point format: %f\n", 1234567.123);

  }
}
//Default floating-point format: 1234567.123000

Display a file in hex.

import java.io.FileInputStream;
public class Main {
  public static void main(String[] argv) throws Exception {
    FileInputStream fin = new FileInputStream("test.txt");
    int i;
    do {
      i = fin.read();
      if (i != -1)
        System.out.printf("%02X ", i);
    } while (i != -1);
    fin.close();
  }
}

Display current time

 
import java.util.Calendar;
public class Main {
  public static void main(String[] argv) throws Exception {
    Calendar cal = Calendar.getInstance();
    System.out.printf("Current time and date: %tc\n", cal);
  }
}

Display short and long date and time formats.

 
import java.text.DateFormat;
import java.util.Date;
class DateFormatDemo {
  public static void main(String args[]) {
    Date date = new Date();
    DateFormat df = DateFormat.getDateInstance(DateFormat.SHORT);
    System.out.println("Short form: " + df.format(date));
  }
}

Floating-point with commas: %,f

  
public class MainClass{
  public static void main(String args[]) {
    System.out.printf("Floating-point with commas: %,f\n", 1234567.123);

  }
}
//Floating-point with commas: 1,234,567.123000

give a known Locale (with the right decimal separator) to bypass the current Locale

 
import java.util.Locale;
public class Main {
  public static void main(String[] argv) {
    System.out.printf(Locale.UK, "%6.2f%n", 123456.7890);
  }
}
//123456.79

Group separators

 
public class Main {
  public static void main(String[] argv) throws Exception {
    System.out.printf("group separators: %,.2f\n\n", 1546456.87);
  }
}

Line up positive and negative values

  
public class MainClass{
  public static void main(String args[]) {
    System.out.printf("Line up positive and negative values:\n");
    System.out.printf("% ,.2f\n% ,.2f\n", 1234567.123, -1234567.123);
  }
}
//Line up positive and negative values:
// 1,234,567.12
//-1,234,567.12

Negative floating-point default: %,f

  
public class MainClass{
  public static void main(String args[]) {
    System.out.printf("Negative floating-point default: %,f\n", -1234567.123);

  }
}
//Negative floating-point default: -1,234,567.123000

Negative floating-point option: %,(f

  
public class MainClass{
  public static void main(String args[]) {
    System.out.printf("Negative floating-point option: %,(f\n", -1234567.123);

  }
}
//Negative floating-point option: (1,234,567.123000)

System.out.format("%f, %1$+020.10f %n", Math.PI)

 
/*
 * Copyright (c) 1995 - 2008 Sun Microsystems, Inc.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 *   - Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 *
 *   - Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in the
 *     documentation and/or other materials provided with the distribution.
 *
 *   - Neither the name of Sun Microsystems nor the names of its
 *     contributors may be used to endorse or promote products derived
 *     from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
 * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */ 
public class Format {
    public static void main(String[] args) {
        System.out.format("%f, %1$+020.10f %n", Math.PI);
    }
}
//3.141593, +00000003.1415926536

System.out.printf( "%-10.10s %s\n", word, word.length() )

 
public class PrintfExamples {
  public static void main(String[] args) {
    String [] words = new String [] { "a", "ape", "asdfasdfasdfasdfasdfasdfasdfadsfasdf" };
    System.out.printf( "%-10s %s\n", "Word", "Length" );
    for ( String word : words )
      System.out.printf( "%-10.10s %s\n", word, word.length() );
  }
}
/*
Word       Length
a          1
ape        3
asdfasdfas 36
*/

System.out.printf("1.0 4f num is %4f\n", 1.0 )

 
public class PrintfExamples {
  public static void main(String[] args) {
    System.out.printf("1.0 5f num is %5f\n", 1.0 );
    System.out.printf("1.0 4f num is %4f\n", 1.0 );

  }
}
/*
1.0 5f num is 1.000000
1.0 4f num is 1.000000
 */

System.out.printf("%1$s://%2$s/%3$s\n", "http", "host", "path")

 
public class PrintfExamples {
  public static void main(String[] args) {

    //http://host/path
    System.out.printf("%1$s://%2$s/%3$s\n", "http", "host", "path");

  }
}
/*
http://host/path

*/

System.out.printf("a %1$s is a %1$s is a %1$s...", "AAA")

 
public class PrintfExamples {
  public static void main(String[] args) {
    System.out.printf("a %1$s is a %1$s is a %1$s...", "AAA");
    System.out.printf("bool is %b\n", "a");
    // char value is a
    System.out.printf("char value is %c\n", "a");
  }
}
/*a AAA is a AAA is a AAA...bool is true
char value is a
*/

System.out.printf("%b %n %c %n %s %n %s %n %d %n",..)

 
/*
 * Copyright (c) 1995 - 2008 Sun Microsystems, Inc.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 *   - Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 *
 *   - Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in the
 *     documentation and/or other materials provided with the distribution.
 *
 *   - Neither the name of Sun Microsystems nor the names of its
 *     contributors may be used to endorse or promote products derived
 *     from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
 * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
import java.io.IOException;
public class PrintfStuff {
  public static void main(String[] args) throws IOException {
    char three[] = { "t", "h", "r", "e", "e" };
    System.out.printf("%b %n %c %n %s %n %s %n %d %n"
        + "%d %n %g %n %g %n %s %n", !false, "3", new String(three), "Three",
        3, Long.MAX_VALUE, Math.PI, Double.MAX_VALUE, new Object());
  }
}
/*true 
 3 
 three 
 Three 
 3 
9223372036854775807 
 3.14159 
 1.79769e+308 
 java.lang.Object@61de33 
*/

System.out.printf("boolean value is %1$b, %1$B\n", true )

 
public class PrintfExamples {
  public static void main(String[] args) {
    //boolean value is true, TRUE
    System.out.printf("boolean value is %1$b, %1$B\n", true );
  }
}
//boolean value is true, TRUE

System.out.printf("float is %-20f!\n", 1.23456789)

 
import java.util.Locale;
public class PrintfExamples {
  public static void main(String[] args) {
    // flags
    System.out.printf("num is %d\n", 5000000);
    System.out.printf("float is %f\n", 1.23456789);
    System.out.printf("float is %.3f\n", 1.23456789);
    System.out.printf("float is %.1f\n", 1.23456789);
    System.out.printf("float is %.0f\n", 1.23456789);
    System.out.printf("float is %-20f!\n", 1.23456789);
  }
}
/*num is 5000000
float is 1.234568
float is 1.235
float is 1.2
float is 1
float is 1.234568    */

System.out.printf("hex value is %1$#x, %1$#X\n", 0xCAFE )

 
import java.util.Date;
public class PrintfExamples {
  public static void main(String[] args) {
    //hex value is b5151397, B5151397
    System.out.printf("hex value is %1$h, %1$H\n", new Date() );
    //hex value 
    System.out.printf("hex value is %1$h, %1$H\n", 0xCAFE );
    //hex value 
    System.out.printf("hex value is %1$x, %1$X\n", 0xCAFE );
    System.out.printf("hex value is %1$#x, %1$#X\n", 0xCAFE );
  }
}
/*hex value is 5a341926, 5A341926
hex value is cafe, CAFE
hex value is cafe, CAFE
hex value is 0xcafe, 0XCAFE*/

System.out.printf(Locale.CHINA, "The date is %tc\n", new Date())

 
import java.util.Date;
import java.util.Locale;
public class PrintfExamples {
  public static void main(String[] args) {
    System.out.printf(Locale.ITALIAN, "The date is %tc\n", new Date());
    System.out.printf(Locale.CHINA, "The date is %tc\n", new Date());
    System.out.printf(Locale.FRENCH, "The date is %tc\n", new Date());
    System.out.printf(Locale.GERMAN, "The date is %tc\n", new Date());
  }
}
/*
The date is ven ott 31 16:28:06 PDT 2008
The date is ??? ?? 31 16:28:07 PDT 2008
The date is ven. oct. 31 16:28:08 PDT 2008
The date is Fr Okt 31 16:28:08 PDT 2008
 */

System.out.printf( Locale.ITALIAN, "value: %f\n", 3.14 )

 
import java.util.Locale;
public class PrintfExamples {
  public static void main(String[] args) {
    System.out.printf( Locale.ITALIAN, "value: %f\n", 3.14 );
  }
}
/*value: 3,140000*/

System.out.printf("num is %03d\n", 5 )

 
public class PrintfExamples {
  public static void main(String[] args) {
    System.out.printf("num is %03d\n", 5 );
  }
}
/*
num is 005
 */

System.out.printf("num is {%07.3f}\n", 3.14 )

 
public class PrintfExamples {
  public static void main(String[] args) {
    System.out.printf("num is %03f\n", 3.14159265 );
    System.out.printf("num is {%07.3f}\n", 3.14 );
    System.out.printf("06.3 num is %06.3f\n", 3.14159265 );
    System.out.printf(".3 num is %.3f\n", 3.14159265 );
    System.out.printf("9.99 num is %4.2f\n", 9.999999999 );

  }
}
/*
num is 3.141593
num is {003.140}
06.3 num is 03.142
.3 num is 3.142
9.99 num is 10.00
 */

System.out.printf("num is %.2f\n", Math.PI )

 
public class PrintfExamples {
  public static void main(String[] args) {

    // num is 3.141593
    System.out.printf("num is %f\n", Math.PI );
    // num is 3.14
    System.out.printf("num is %.2f\n", Math.PI );
  }
}
/*
num is 3.141593
num is 3.14

*/

System.out.printf("num is %s\n", 5)

 
public class PrintfExamples {
  public static void main(String[] args) {

    System.out.printf("num is %s\n", 5);
    System.out.printf("char is %s\n", "a");
    System.out.printf("char is %S\n", "a");
    System.out.printf("bool is %s\n", true );
  }
}
/*
num is 5
char is a
char is A
bool is true
*/

System.out.printf("sci not num is %e\n", 3000000.0 )

 
public class PrintfExamples {
  public static void main(String[] args) {
    System.out.printf("sci not num is %e\n", 3.14159265*10000 );
    System.out.printf("sci not num is %g\n", 3.14159265*10000 );
    System.out.printf("sci not num is %e\n", 0.123456789 );
    System.out.printf("sci not num is %g\n", 0.123456789 );
    System.out.printf("sci not num is %e\n", 3000000.0 );
    System.out.printf("hex num is %h\n", 1.0 );
    System.out.printf("num is %h\n", 0xCAFE );
  }
}
/*
sci not num is 3.141593e+04
sci not num is 31415.9
sci not num is 1.234568e-01
sci not num is 0.123457
sci not num is 3.000000e+06
hex num is 3ff00000
num is cafe
 */

System.out.printf("%s://%s/%s\n", "http", "host", "path")

 
public class PrintfExamples {
  public static void main(String[] args) {
    System.out.printf("My name is %s\n", "Joe");
    System.out.printf("%s://%s/%s\n", "http", "host", "path");
  }
}
/*
My name is Joe
http://host/path
 */

System.out.printf("String is "%-5s"\n", "A")

 
public class PrintfExamples {
  public static void main(String[] args) {
    System.out.printf("String is "%5s"\n", "A");
    System.out.printf("String is "%-5s"\n", "A");
    System.out.printf("String is "%.5s"\n", "Happy Birthday!");
  }
}
/*
String is "    A"
String is "A    "
String is "Happy"

*/

System.out.printf("The DATE is %Tc\n", new Date() )

 
import java.util.Date;
import java.util.Locale;
public class PrintfExamples {
  public static void main(String[] args) {

    System.out.printf("The date is %s\n", new Date() );
    System.out.printf("The date is %tc\n", new Date() );
    System.out.printf("The DATE is %Tc\n", new Date() );
  }
}
/*
The date is Fri Oct 31 16:30:25 PDT 2008
The date is Fri Oct 31 16:30:25 PDT 2008
The DATE is FRI OCT 31 16:30:25 PDT 2008
 */

System.out.printf("The DATE is %tr\n", new Date() )

 
import java.util.Date;
import java.util.Locale;
public class PrintfExamples {
  public static void main(String[] args) {
    System.out.printf("The DATE is %tD\n", new Date() );
    System.out.printf("The DATE is %tF\n", new Date() );
    System.out.printf("The DATE is %tr\n", new Date() );
    System.out.printf("The DATE is %tR\n", new Date());
    System.out.printf("The DATE is %tT\n", new Date());
  }
}
/*
The DATE is 10/31/08
The DATE is 2008-10-31
The DATE is 04:29:46 PM
The DATE is 16:29
The DATE is 16:29:46
 */

System.out.printf("The DATE is %tz\n", new Date() )

 
import java.util.Date;
public class PrintfExamples {
  public static void main(String[] args) {

    System.out.printf("The DATE is %tC\n", new Date() );
    System.out.printf("The DATE is %tz\n", new Date());
  }
}
/*
The DATE is 20
The DATE is -0800

*/

Two decimal digits

 

public class Main {
  public static void main(String[] argv) throws Exception {
    System.out.printf("Two decimal digits: %.2f\n", 10.0 / 3.0);
  }
}

Use printf(): %10s %10s %10s

 

public class Main {
  public static void main(String[] argv) throws Exception {
    System.out.printf("%10s %10s %10s\n", "this", "is", "a test");
  }
}
//      this         is     a test

Use printf(): align float numbers

 

public class Main {
  public static void main(String[] argv) throws Exception {
    for (double i = 1.0; i < 20.0; i++)
      System.out.printf("%10.2f %10.2f %10.2f\n", i, Math.sqrt(i), i * i);
  }
}
/*    1.00       1.00       1.00
      2.00       1.41       4.00
      3.00       1.73       9.00
      4.00       2.00      16.00
      5.00       2.24      25.00
      6.00       2.45      36.00
      7.00       2.65      49.00
      8.00       2.83      64.00
      9.00       3.00      81.00
     10.00       3.16     100.00
     11.00       3.32     121.00
     12.00       3.46     144.00
     13.00       3.61     169.00
     14.00       3.74     196.00
     15.00       3.87     225.00
     16.00       4.00     256.00
     17.00       4.12     289.00
     18.00       4.24     324.00
     19.00       4.36     361.00
*/

Use printf(): group separators

 

public class Main {
  public static void main(String[] argv) throws Exception {
    System.out.printf("Use group separators: %,.2f\n\n", 123456.87);
  }
}
//Use group separators: 123,456.87

Use printf() to create a time stamp.

 
import java.io.FileWriter;
import java.io.PrintWriter;
import java.util.Calendar;
public class Main {
  static void timeStamp(String msg, PrintWriter pw) {
    Calendar cal = Calendar.getInstance();
    pw.printf("%s %tc\n", msg, cal);
  }
  public static void main(String args[]) throws Exception {
    PrintWriter pw = new PrintWriter(new FileWriter("logfile.txt", true));
    timeStamp("File opened", pw);
    pw.close();
    if (pw.checkError())
      System.out.println("I/O error occurred.");
  }
}

Use printf(): Two decimal digits

 

public class Main {
  public static void main(String[] argv) throws Exception {
    System.out.printf("Two decimal digits: %.2f\n", 10.0 / 3.0);
  }
}
//Two decimal digits: 3.33