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Thread: Strings and Characters

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    Default Strings and Characters

    Hello

    I would like to write a method called displayString() which takes a string as an argument and returns no result.


    I already have a working method I wrote called displayCharacter() which takes a single argument of type char called aCharacter.

    UpInLights is my class and when I create an instance of UpInLights:

    UpInLights lights = new UpInLights() and then execute the following: lights.displayCharacter("V");

    the letter V is displayed


    The method displayString() must use the displayCharacter() method within its method. The displayString() method should iterate over the String that is to be
    displayed. On each iteration the method should send a displayCharacter() message with the current element as its argument to the receiver.

    The result will be the following: lights.displayString("HELLO"); will display HELLO

    I am inexperienced and wouldn't know where to start so can't even post what I think is correct, but I am keen to learn and would love to know how this
    mini exercise can be achieved.

    Many thanks.


  2. #2
    Super Moderator Norm's Avatar
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    Default Re: Strings and Characters

    The displayString() method should iterate over the String that is to be
    displayed
    Have you read the String class API documentation? The String class has methods to get at the individual characters in the String. You could write a loop to iterate over the String and get the char one by one.

    Where is displayCharacter() displaying the argument it receives?

    There is some disagreement between your documentation and your code:
    lights.displayCharacter("V"); // here the arg is a String not a char.
    chars are delimited by '

    displayCharacter() which takes a single argument of type char
    Last edited by Norm; July 3rd, 2011 at 02:33 PM.

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    Default Re: Strings and Characters

    The displayCharacter() is displaying the argument it receives in an Array.

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    Default Re: Strings and Characters

    Hi Norm , how could I write a loop to iterate over the String and get the char one by one?

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    Default Re: Strings and Characters

    Ok. Normally I think of "display" as something that a human can see. Putting a value in an array is differeent than displaying it.
    You "display" a String by using System.out.println to a console or by putting it in a GUI component like a text field.

  6. #6
    Super Moderator Norm's Avatar
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    Default Re: Strings and Characters

    could I write a loop to iterate over the String and get the char one by one?
    You do it pretty much just like you asked:
    write a loop -> See for() loop for example
    in the loop get the char from the String one by one -> Read the String class API doc for the method

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    Default Re: Strings and Characters

    for (char aChar = 0; char < 4; char++); something like this for HELLO ?

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    Default Re: Strings and Characters

    CORRECTION for (char aChar = 0; achar < 4; achar++); something like this for HELLO ?

  9. #9
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    Default Re: Strings and Characters

    Not quite.
    You should use the length of the String to control the number of loops. Don't hard code a 4.
    You've mixed the data type and the variable name: char aChar = 0; char < 4; char++
    char is a data type, aChar is a variable name

    What is the variable aChar being used for inside of the loop? Normally loop control variables are int.

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    Default Re: Strings and Characters

    Sorry for (int i = 0; i < string.length; i++) ?

  11. #11
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    Default Re: Strings and Characters

    Time to use the compiler and see what it thinks.

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    Default Re: Strings and Characters

    I dont quite know how to incorporate the loop statement with everything else - sorry just not syntactically or semantically there!

  13. #13
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    Default Re: Strings and Characters

    Just start with the loop.
    Then add the other stuff one thing at a time.

    There are hundreds of pieces of code on this forum and thousands on the internet.
    Search here or Google for samples.

    Also read the Java Tutorial: http://download.oracle.com/docs/cd/E...vase/tutorial/
    Last edited by Norm; July 3rd, 2011 at 03:33 PM. Reason: Where to get code samples

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