Java rmat And Printf Methods - O7planning

Trang chủ » Câu Lệnh Printf Trong Java » Java rmat And Printf Methods - O7planning

Có thể bạn quan tâm

  • All Tutorials
  • Java
    • Java Basic
    • Java Collections Framework
    • Java IO
    • Java New IO
    • Java Date Time
    • Servlet/JSP
    • Eclipse Tech
      • SWT
      • RCP
      • RAP
      • Eclipse Plugin Tools
    • XML & HTML
    • Java Opensource
    • Java Application Servers
  • Maven
  • Gradle
  • Servlet/Jsp
  • Thymeleaf
  • Spring
    • Spring Boot
    • Spring Cloud
  • Struts2
  • Hibernate
  • Java Web Service
  • JavaFX
  • SWT
  • Oracle ADF
  • Android
  • iOS
  • Python
  • Swift
  • C#
  • C/C++
  • Ruby
  • Dart
  • Batch
  • Database
    • Oracle
    • MySQL
    • SQL Server
    • PostGres
    • Other Database
  • Oracle APEX
  • Report
  • Client
  • ECMAScript / Javascript
  • TypeScript
  • NodeJS
  • ReactJS
  • Flutter
  • AngularJS
  • HTML
  • CSS
  • Bootstrap
  • OS
    • Ubuntu
    • Solaris
    • Mac OS
  • Browser
  • Git
  • SAP
  • Amazon AWS
  • Others
    • Chưa phân loại
    • Phần mềm & ứng dụng tiện ích
    • VirtualBox
    • VmWare
Java String.format() and printf() methods
  1. printf()
  2. Format rules
  3. conversion-character
  4. width
  5. flags
  6. precision

1. printf()

In Java programming, you often come across System.out.printf(..) code. Actually, method printf(..) is defined in both PrintStream and PrintWriter classes, their usage is similar, printf stands for "Print + Format".printf methods// Definition of the printf methods in the PrintWriter class: public PrintStream printf(Locale l, String format, Object... args) public PrintStream printf(String format, Object... args) // Definition of the printf methods in PrintWriter class: public PrintWriter printf(Locale l, String format, Object... args) public PrintWriter format(String format, Object... args)
  • Java PrintStream
  • Java PrintWriter
System.out.printf(..) is a special case, used to write a formatted text to the Console screen, where System.out is essentially an object of type PrintStream.System classpackage java.lang; public final class System { public static final PrintStream out = ...; }Before we start, let's see a simple example:Printf_ex1.javapackage org.o7planning.printf.ex; public class Printf_ex1 { public static void main(String[] args) { String firstName = "James"; String lastName = "Smith"; int age = 20; System.out.printf("My name is %s %s, I'm %d years old.", firstName, lastName, age); } }Output:My name is James Smith, I'm 20 years old.

2. Format rules

%[flags][width][.precision]conversion-characterThese parameters: flags, width, precision are optional.

3. conversion-character

%[flags][width][.precision]conversion-character
conversion-characterDescriptionType
ddecimal integerbyte, short, int, long
ffloating-point numberfloat, double
bBooleanObject
Bwill uppercase the booleanObject
cCharacter CapitalString
Cwill uppercase the letterString
sString CapitalString
Swill uppercase all the letters in the stringString
hhashcode - A hashcode is like an address. This is useful for printing a referenceObject
nnewline - Platform specific newline character - use %n instead of \n for greater compatibility
conversion-character: nSystem.out.printf("One%nTwo%nThree");Output:One Two Threeconversion-character: sSystem.out.printf("My name is %s %s", "James", "Smith");Output:My name is James Smithconversion-character: SSystem.out.printf("My name is %S %S", "James", "Smith");Output:My name is JAMES SMITHconversion-character: bSystem.out.printf("%b%n", null); System.out.printf("%b%n", false); System.out.printf("%b%n", 5.3); System.out.printf("%b%n", "Any text"); System.out.printf("%b%n", new Object());Output:false false true true trueconversion-character: BSystem.out.printf("%B%n", null); System.out.printf("%B%n", false); System.out.printf("%B%n", 5.3); System.out.printf("%B%n", "Any text"); System.out.printf("%B%n", new Object());Output:FALSE FALSE TRUE TRUE TRUEconversion-character: dSystem.out.printf("There are %d teachers and %d students in the class", 2, 25);Output:There are 2 teachers and 25 students in the classconversion-character: fSystem.out.printf("Exchange rate today: EUR %f = USD %f", 1.0, 1.2059);Output:Exchange rate today: EUR 1.000000 = USD 1.205900conversion-character: cchar ch = 'a'; System.out.printf("Code of '%c' character is %d", ch, (int)ch);Output:Code of 'a' character is 97conversion-character: Cchar ch = 'a'; System.out.printf("'%C' is the upper case of '%c'", ch, ch);Output:'A' is the upper case of 'a'conversion-character: hPrintf_cc_h_ex.javapackage org.o7planning.printf.ex; public class Printf_cc_h_ex { public static void main(String[] args) { // h (Hashcode HEX) Object myObject = new AnyObject("Something"); System.out.println("Hashcode: " + myObject.hashCode()); System.out.println("Identity Hashcode: " + System.identityHashCode(myObject)); System.out.println("Hashcode (HEX): " + Integer.toHexString(myObject.hashCode())); System.out.println("toString : " + String.valueOf(myObject)); System.out.printf("Printf: %h", myObject); } } class AnyObject { private String val; public AnyObject(String val) { this.val = val; } @Override public int hashCode() { if (this.val == null || this.val.isEmpty()) { return 0; } return 1000 + (int) this.val.charAt(0); } }Output:Hashcode: 1083 Identity Hashcode: 1579572132 Hashcode (HEX): 43b toString : org.o7planning.printf.ex.AnyObject@43b Printf: 43b

4. width

%[flags][width][.precision]conversion-characterwidth - specifies the minimum amount of space (number of characters) to hold for printing the contents of a corresponding argument.printf(format, arg1, arg2,.., argN)

5. flags

%[flags][width][.precision]conversion-character
flagDescription
-left-justify (default is to right-justify )
+output a plus ( + ) or minus ( - ) sign for a numerical value
0forces numerical values to be zero-padded (default is blank padding )
,comma grouping separator (for numbers > 1000)
space will display a minus sign if the number is negative or a space if it is positive
flag: -String[] fullNames = new String[] {"Tom", "Jerry", "Donald"}; float[] salaries = new float[] {1000, 1500, 1200}; // s System.out.printf("|%-10s | %-30s | %-15s |%n", "No", "Full Name", "Salary"); for(int i=0; i< fullNames.length; i++) { System.out.printf("|%-10d | %-30s | %15f |%n", (i+1), fullNames[i], salaries[i]); }Output:flag: +// flag: + System.out.printf("The world's economy increased by %+f percent in 2020. %n", -3.3); System.out.printf("China's economy increased by %+f percent in 2020. %n", 2.3); System.out.println(); // without flag: + System.out.printf("The world's economy increased by %f percent in 2020. %n", -3.3); System.out.printf("China's economy increased by %f percent in 2020. %n", 2.3);Output:The world's economy increased by -3.300000 percent in 2020. China's economy increased by +2.300000 percent in 2020. The world's economy increased by -3.300000 percent in 2020. China's economy increased by 2.300000 percent in 2020.flag: 0 (zero)// flag: 0 & with: 20 System.out.printf("|%020f|%n", -3.1); // without flag & with: 20 System.out.printf("|%20f|%n", -3.1); // flag: - (left align) & with: 20 System.out.printf("|%-20fOutput:flag: , (comma)// flag: , System.out.printf("%,f %n", 12345678.9); // flag: , System.out.printf("%,f %n", -12345678.9);Output:12,345,678.900000 -12,345,678.900000flag: (space)// flag: (space) System.out.printf("% f %n", 12345678.9); System.out.printf("% f %n", -12345678.9); System.out.println(); // flags: , (space + comma) System.out.printf("% ,f %n", 12345678.9); System.out.printf("% ,Output:12345678.900000 -12345678.900000 12,345,678.900000 -12,345,678.900000

6. precision

%[flags][width][.precision]conversion-characterSystem.out.printf("%f %n", 12345678.911); System.out.printf("%f %n", -12345678.911); System.out.println(); // flag: , (comma) System.out.printf("%,f %n", 12345678.911); // flag: , (comma) System.out.printf("%,f %n", -12345678.911); System.out.println(); // flags: , (space + comma) System.out.printf("% ,f %n", 12345678.911); // flags: , (space + comma) System.out.printf("% ,f %n", -12345678.911); System.out.println(); // flag: , (comma) & precision: .2 System.out.printf("%,.2f %n", 12345678.911); // flag: , (comma) & precision: .3 System.out.printf("%,.3f %n", -12345678.911); System.out.println(); // flags: , (space + comma) & precision: .2 System.out.printf("% ,.2f %n", 12345678.911); // flags: , (space + comma) & precision: .3 System.out.printf("% ,.3f %n", -12345678.911);Output:12345678.911000 -12345678.911000 12,345,678.911000 -12,345,678.911000 12,345,678.911000 -12,345,678.911000 12,345,678.91 -12,345,678.911 12,345,678.91 -12,345,678.911

Java Basic

  • Customize java compiler processing your Annotation (Annotation Processing Tool)
  • Java Programming for team using Eclipse and SVN
  • Java WeakReference Tutorial with Examples
  • Java PhantomReference Tutorial with Examples
  • Java Compression and Decompression Tutorial with Examples
  • Configuring Eclipse to use the JDK instead of JRE
  • Java String.format() and printf() methods
  • Syntax and new features in Java 8
  • Java Regular Expressions Tutorial with Examples
  • Java Multithreading Programming Tutorial with Examples
  • JDBC Driver Libraries for different types of database in Java
  • Java JDBC Tutorial with Examples
  • Get the values of the columns automatically increment when Insert a record using JDBC
  • Java Stream Tutorial with Examples
  • Java Functional Interface Tutorial with Examples
  • Introduction to the Raspberry Pi
  • Java Predicate Tutorial with Examples
  • Abstract class and Interface in Java
  • Access modifiers in Java
  • Java Enums Tutorial with Examples
  • Java Annotations Tutorial with Examples
  • Comparing and Sorting in Java
  • Java String, StringBuffer and StringBuilder Tutorial with Examples
  • Java Exception Handling Tutorial with Examples
  • Java Generics Tutorial with Examples
  • Manipulating files and directories in Java
  • Java BiPredicate Tutorial with Examples
  • Java Consumer Tutorial with Examples
  • Java BiConsumer Tutorial with Examples
  • What is needed to get started with Java?
  • History of Java and the difference between Oracle JDK and OpenJDK
  • Install Java on Windows
  • Install Java on Ubuntu
  • Install OpenJDK on Ubuntu
  • Install Eclipse
  • Install Eclipse on Ubuntu
  • Quick Learning Java for beginners
  • History of bits and bytes in computer science
  • Data Types in java
  • Bitwise Operations
  • if else statement in java
  • Switch Statement in Java
  • Loops in Java
  • Arrays in Java
  • JDK Javadoc in CHM format
  • Inheritance and polymorphism in Java
  • Java Function Tutorial with Examples
  • Java BiFunction Tutorial with Examples
  • Example of Java encoding and decoding using Apache Base64
  • Java Reflection Tutorial with Examples
  • Java remote method invocation - Java RMI Tutorial with Examples
  • Java Socket Programming Tutorial with Examples
  • Which Platform Should You Choose for Developing Java Desktop Applications?
  • Java Commons IO Tutorial with Examples
  • Java Commons Email Tutorial with Examples
  • Java Commons Logging Tutorial with Examples
  • Understanding Java System.identityHashCode, Object.hashCode and Object.equals
  • Java SoftReference Tutorial with Examples
  • Java Supplier Tutorial with Examples
  • Java Aspect Oriented Programming with AspectJ (AOP)
Show More
  • Java Servlet/Jsp Tutorials
  • Java Collections Framework Tutorials
  • Java API for HTML & XML
  • Java IO Tutorials
  • Java Date Time Tutorials
  • Spring Boot Tutorials
  • Maven Tutorials
  • Gradle Tutorials
  • Java Web Services Tutorials
  • Java SWT Tutorials
  • JavaFX Tutorials
  • Java Oracle ADF Tutorials
  • Struts2 Framework Tutorials
  • Spring Cloud Tutorials

Java Basic

  • Customize java compiler processing your Annotation (Annotation Processing Tool)
  • Java Programming for team using Eclipse and SVN
  • Java WeakReference Tutorial with Examples
  • Java PhantomReference Tutorial with Examples
  • Java Compression and Decompression Tutorial with Examples
  • Configuring Eclipse to use the JDK instead of JRE
  • Java String.format() and printf() methods
  • Syntax and new features in Java 8
  • Java Regular Expressions Tutorial with Examples
  • Java Multithreading Programming Tutorial with Examples
  • JDBC Driver Libraries for different types of database in Java
  • Java JDBC Tutorial with Examples
  • Get the values of the columns automatically increment when Insert a record using JDBC
  • Java Stream Tutorial with Examples
  • Java Functional Interface Tutorial with Examples
  • Introduction to the Raspberry Pi
  • Java Predicate Tutorial with Examples
  • Abstract class and Interface in Java
  • Access modifiers in Java
  • Java Enums Tutorial with Examples
  • Java Annotations Tutorial with Examples
  • Comparing and Sorting in Java
  • Java String, StringBuffer and StringBuilder Tutorial with Examples
  • Java Exception Handling Tutorial with Examples
  • Java Generics Tutorial with Examples
  • Manipulating files and directories in Java
  • Java BiPredicate Tutorial with Examples
  • Java Consumer Tutorial with Examples
  • Java BiConsumer Tutorial with Examples
  • What is needed to get started with Java?
  • History of Java and the difference between Oracle JDK and OpenJDK
  • Install Java on Windows
  • Install Java on Ubuntu
  • Install OpenJDK on Ubuntu
  • Install Eclipse
  • Install Eclipse on Ubuntu
  • Quick Learning Java for beginners
  • History of bits and bytes in computer science
  • Data Types in java
  • Bitwise Operations
  • if else statement in java
  • Switch Statement in Java
  • Loops in Java
  • Arrays in Java
  • JDK Javadoc in CHM format
  • Inheritance and polymorphism in Java
  • Java Function Tutorial with Examples
  • Java BiFunction Tutorial with Examples
  • Example of Java encoding and decoding using Apache Base64
  • Java Reflection Tutorial with Examples
  • Java remote method invocation - Java RMI Tutorial with Examples
  • Java Socket Programming Tutorial with Examples
  • Which Platform Should You Choose for Developing Java Desktop Applications?
  • Java Commons IO Tutorial with Examples
  • Java Commons Email Tutorial with Examples
  • Java Commons Logging Tutorial with Examples
  • Understanding Java System.identityHashCode, Object.hashCode and Object.equals
  • Java SoftReference Tutorial with Examples
  • Java Supplier Tutorial with Examples
  • Java Aspect Oriented Programming with AspectJ (AOP)
Show More
  • Java Servlet/Jsp Tutorials
  • Java Collections Framework Tutorials
  • Java API for HTML & XML
  • Java IO Tutorials
  • Java Date Time Tutorials
  • Spring Boot Tutorials
  • Maven Tutorials
  • Gradle Tutorials
  • Java Web Services Tutorials
  • Java SWT Tutorials
  • JavaFX Tutorials
  • Java Oracle ADF Tutorials
  • Struts2 Framework Tutorials
  • Spring Cloud Tutorials

Newest Articles

  • Introduction to Amazon ACM
  • Transfer domain registration to Amazon Route 53
  • Request an SSL certificate from Amazon ACM
  • Amazon CloudFront Invalidation
  • Migrate DNS service to Amazon Route 53
  • Configure Amazon CloudFront Error Pages
  • Create a CloudFront distribution for S3 Bucket
  • Amazon AWS Policy Generator - policygen
  • Amazon S3 Bucket policies
  • Configure custom domain and SSL for CloudFront distribution
  • Create Amazon S3 Bucket
  • Configure custom domain for Amazon S3 static website
  • Host a static website on Amazon S3
  • JPA Join types and syntax in JPQL
  • Get started with JPA Criteria Query API
  • Fetch data with Spring Data JPA DTO Projections
  • List, submit and delete Sitemaps with Google Search Java API
  • List, add and delete Sites with Google Search Java API
  • Create a Google Service Account
  • Setup environment variables on Windows
Show More
  • Java Basic

Từ khóa » Câu Lệnh Printf Trong Java