Aroma 1: Arguments to Appl

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Aroma 1 Arguments to Appl

• Special Topics Java

Dr. Tim Margush Department of Mathematics and
Computer Science The University of Akron
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Command Line Arguments

• Used in applications
• Command line always looks like this
• java classname command line arguments
• This invokes the method main in the named class
• main has one argument - an array of Strings
• words are parsed into array components

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Application Main

• public static void main ( String argv )
• System.out.println(
• "Number of arguments specified "
• argv.length)
• int j, sum 0
• for (j0 jltargv.length j)
• sum Integer.valueOf(argvj).intValue()
• System.out.println("--"j"-gt"argvj"lt---")
• System.out.println( "Sum of arguments is "
  sum)

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Illustration argv

• argv ref0___gt"first_word"
• ref1___gt"second_word"
• ref2___gt"third_word"
• argv.length is 3

first_word
second_word
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third_word
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3
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Type Conversion

• Integer.valueOf(argvj).intValue()
• class Integer contains a class method, valueOf
• takes a String and constructs an Integer object
  with the value represented by the String
• class Integer has an instance method, intValue
• returns a primitive int whose value matches that
  of the Integer object

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String Concatenation?

• this concatenation ("--"j"-gt"argvj"lt---"
• becomes new StringBuffer()
• .append("--").append(j).append("-gt")
• .append(argvj).append("lt---).toString()
• Concatenation uses the StringBuffer class
• StringBuffer has an append for most data types
• method toString() converts the StringBuffer
  object back to a String expected by the print
  method

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Applet Arguments

• Applet tag can include named parameters
• ltapplet code"ParamApplet" width525 height100gt
• ltparam namemyName value"Johnny Appleseed"gt
• ltparam nameBGColor value"008000"gt
• ltparam name"FGColor" value"FFFFFF"gt
• ltparam name"Font Size" value"64"gt
• lt/appletgt

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Applet Accessing Arguments

• String sFontSize, sMyName
• Integer iFontSize
• sMyName getParameter ("myName")
• if (sMyNamenull) sMyName"Mr. Dephault"
• sFontSize getParameter ("Font Size")
• if (sFontSizenull) sFontSize"32"
• iFontSize Integer.valueOf(sFontSize).intValue()