Java Tool Classes-date acquisition, random number, System command, data type conversion

1  Packagetems;2 3 ImportJava.text.SimpleDateFormat;4 Importjava.util.Arrays;5 ImportJava.util.Calendar;6 Importjava.util.Date;7 Importjava.util.List;8 ImportJava.util.Random;9 ImportJava.util.Scanner;Ten  One /** A * Math class -  *  -  * */ the classdemo6{ -      Public Static voidMain (string[] args) { -         //take an integer -Math.ceil (34.5);//returns the smallest integer greater than this number +Math.floor (34.5);//returns the largest integer less than this number -         //Square or root +Math.pow (2,3); A         //Rounding atMath.Round (12.54); -     } - } - /** - * Date Class -  *  in  * */ - classdemo2{ to      Public Static voidMain (string[] args)throwsException { +         //Get current Time -Date Date =NewDate (); the         //perform the format of the date display in your own way *SimpleDateFormat SDF =NewSimpleDateFormat ("Yyyy/mm/dd E HH:mm:ss"); $String SSS =Sdf.format (date);Panax Notoginseng         //string-to-date (date) -String s= "2015-03-08"; theSimpleDateFormat sdf2=NewSimpleDateFormat ("yyyy-dd-mm"); + Sdf.parse (s); A     } the } + /** - * Calendar class $  *  $  * */ - classdemo3{ -      Public Static voidMain (string[] args) { theCalendar c=calendar.getinstance (); -         //get year Month dayWuyiC.get (calendar.year);//years theC.get (calendar.month+1);//Month -C.get (Calendar.day_of_month);//Day WuC.get (Calendar.day_of_week);//Week -         //Set Date About         //set (int year,int month,int date) $C.set (2012,2,18); -         //Add and delete the current date -C.add (Calendar.day_of_month, 18); -     } A } + /** the * Random class -  *  $  * */ the classdemo4{ the      Public Static voidMain (string[] args) { theRandom r =NewRandom (); the         intRandom = R.nextint (10) +1; -     } in } the /** the * Scanner class About  *  the  * */ the classdemo5{ the      Public Static voidMain (string[] args) { +         //entering data from the keyboard -Scanner Scanner =NewScanner (system.in); the         intGuess =scanner.nextint ();Bayi         //in the case of OJ, the input method used in the face of uncertain data the         //While (Sc.hasnext ()) {} the      -     } - } the /** the * Runtime class the  *  the  */ -  the classDemo { the     /*The GetRuntime () method is required to get the runtime object the * The runtime class is a simple interest design pattern. 94 * Note: runtime can only kill Java Virtual machine-initiated processes. Do not kill the system process*/ the      Public Static voidMain (string[] args)throwsException { theRuntime Run=runtime.getruntime ();//get the current running object theProcess p=run.exec ("C:\\winmine.exe");//Open Process98P.destroy ();//Close Process AboutProcess p1=run.exec ("notepad.exe demo.txt"); - P1.destroy ();101         102     }103     104 } the /**106 * Conversion between data types107  * 108  * */109 classdemo7{ the      Public Static voidMain (string[] args) {111 //Binary Conversion the         //decimal to other binary:113String S1 = integer.tohexstring (60); the         //other binary into decimal: theInteger.parseint ("3c", 16);  the //Arrays <-> Collections117List <string>al=arrays.aslist (S1);118String S[]=al.toarray (NewString[10]);119     } -}

Java Tool Classes-date acquisition, random number, System command, data type conversion