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Roskilde edb-skole Prog1:\OpgaverAlm\Main.doc 2003-04-02 /Michael Claudius COMPUTER SUBJECT: BASIC JAVA PROGRAMMING TYPE: EXERCISE/DISCUSSION IDENTIFICATION: MAIN/MC COPYRIGHT: Michael Claudius LEVEL: EASY DURATION: 15 - 40 minutes SIZE: 10-15 lines!! OBJECTIVE: Use of TextPad and understanding the composition of a Java-program. REQUIREMENTS: Ken Arnold & James Gosling Ch. 1 OR Koffman Ch. 5.1 COMMANDS: Roskilde edb-skole Prog1:\OpgaverAlm\Main.doc 2003-04-02 /Michael Claudius IDENTIFICATION: MAIN/MC The problem What is behind the mysterious args-array in the public void main(String[] args) method ? We will take a closer look at this and what the args stands for and what it can be used for. Assignment 1 Start to type in the HelloWorld program: import java.util.* class HelloWorld { public static void main (String[] args) { System.out.println("Hello world"); System.out.println(args[0]); } } Compile the source-code as usual. (Select ”Tools” from the menu and choose ”Compile Java” OR press <Ctrl>+<1>) From the ”Tools”-menu, choose ”Run Java Application” OR press <Ctrl>+<2>) Then you will get an IndexOutOfBoundsException. Why? Assignment 2. From the ”Tools”-menu, choose ”Run…" instead. Then a special dialogwindow pops up. Fill out the textfields: command with "java" parameter must be the name of the class: "HelloWorld" and mark it as a DOS command as shown below: Click on OK. You are now running it from a DOS-prompt and you still have the exception ! Try to run again, but this time fill the textfield "parameter" with "HelloWorld Hi my name is xx ". Look at the print out. Explain what happened ! Roskilde edb-skole Prog1:\OpgaverAlm\Main.doc 2003-04-02 /Michael Claudius Assignment 3 Set up a for-loop and print out all values of the args-array. Explain what args is! Assignment 4 Try to sort the args by using the method sort in Arrays class in package java.util: Arrays.sort(args) Compile and run !