Java codes for professional and beginners

/* Check if string contains valid number example. This example shows how to check if string contains valid number or not using parseDouble and parseInteger methods of Double and Integer wrapper classes. */   public class CheckValidNumberExample {   public static void main ( String [ ] args ) {   String [ ] str = new String [ ] { "10.20" , "123456" , "12.invalid" } ;   for ( int i = 0 ; i < str. length ; i ++ ) {   if ( str [ i ] . indexOf ( "." ) > 0 ) {   try { /* * To check if the number is valid decimal number, use * double parseDouble(String str) method of * Double wrapper class. * * This method throws NumberFormatException if the * argument string is not a valid decimal number. */ Double . parseDouble ( str [ i ] ) ; System . out . println ( str [ i ] + " is a valid decimal number" ) ; } ...

/* Set Thread Name Example This Java example shows how to set name of thread using setName method of Thread class. */   public class SetThreadNameExample {   public static void main ( String [ ] args ) {   //get currently running thread object Thread currentThread = Thread . currentThread ( ) ; System . out . println ( currentThread ) ;   /* * To set name of thread, use * void setName(String threadName) method of * Thread class. */   currentThread. setName ( "Set Thread Name Example" ) ;   /* * To get the name of thread use, * String getName() method of Thread class. */ System . out . println ( "Thread Name : " + currentThread. getName ( ) ) ; } }   /* Output of the example would be Thread[main,5,main] Thread Name : Set Thread Name Example */

/*   Pause Thread Using Sleep Method Example   This Java example shows how to pause currently running thread using   sleep method of Java Thread class. */   public class PauseThreadUsingSleep {   public static void main ( String [ ] args ) {   /* * To pause execution of a thread, use * void sleep(int milliseconds) method of Thread class. * * This is a static method and causes the suspension of the thread * for specified period of time. * * Please note that, this method may throw InterruptedException. */   System . out . println ( "Print number after pausing for 1000 milliseconds" ) ; try {   for ( int i = 0 ; i < 5 ; i ++ ) {   System . out . println ( i ) ;   /* * This thread will pause for 1000 milliseconds after * printing each number. */ Thread . sleep ( 1000 ) ; } } catch ( InterruptedException ie ) { System . ou...

/* Get Current Thread Example This Java example shows how to get reference of current thread using currentThread method of Java Thread class. */   public class GetCurrentThreadExample {   public static void main ( String [ ] args ) {   /* * To get the reference of currently running thread, use * Thread currentThread() method of Thread class. * * This is a static method. */   Thread currentThread = Thread . currentThread ( ) ; System . out . println ( currentThread ) ;   } }   /* Output of the example would be Thread[main,5,main] */

/* Create New Thread Using Runnable Example This Java example shows how to create a new thread by implementing Java Runnable interface. */   /*  * To create a thread using Runnable, a class must implement  * Java Runnable interface.  */ public class CreateThreadRunnableExample implements Runnable {   /* * A class must implement run method to implement Runnable * interface. Signature of the run method is, * * public void run() * * Code written inside run method will constite a new thread. * New thread will end when run method returns. */ public void run ( ) {   for ( int i = 0 ; i < 5 ; i ++ ) { System . out . println ( "Child Thread : " + i ) ;   try { Thread . sleep ( 50 ) ; } catch ( InterruptedException ie ) { System . out . println ( "Child thread interrupted! " + ie ) ; } }   System . out . println ( "Child thread finished!" ) ; }   ...

/* Java Class example. This Java class example describes how class is defined and being used in Java language.   Syntax of defining java class is, <modifier> class <class-name>{   // members and methods } */   public class JavaClassExample { /*   Syntax of defining memebers of the java class is,   <modifier> type <name>;   */ private String name ; /*   Syntax of defining methods of the java class is,   <modifier> <return-type> methodName(<optional-parameter-list>) <exception-list>{   ...   }   */ public void setName ( String n ) { //set passed parameter as name name = n ; } public String getName ( ) { //return the set name return name ; } //main method will be called first when program is executed public static void main ( String args [ ] ) { /*   Syntax of java object cre...