WEBVTT

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In this demo i'm going to show you what happens

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when you try to compile code that 

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breaks the rules in someway

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this is the same code you saw in the last demo

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for the bicycle class, but with one small change

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let's complie this and see what happens.

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The first thing we see is an error message

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at the foot of the editor window here

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this tell us there is a syntax error in the code

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something that breaks the rules of the

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programming language

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the message tries to help us and

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explain what the error is

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it says semi-colon expected.

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One of the rules of Java is that lines of code

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should end in a semi-colon

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so it looks like we have missed a semi-colon

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at the end of one of the lines.

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So there is a missing semi-colon, but where

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the compiler helps by highlighting in the editor

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the line of code where it has found the error.

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Thats the same line of code 

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I edited in the previous demo

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and it looks like i've now accidentially deleted a semi-colon

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that message was quite straightforward but sometimes it

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could be more difficult to understand 

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what an error message is telling you.

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If you click on the question mark button

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BlueJ will try to give you a hint

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and sometimes these hints can be quite useful

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it's certainly not unusual to come across syntax

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errors as you're creating code

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and one of the important skills of a programmer

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is to be able to use the compiler error messages

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in order to fix those errors and get the code working.

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So now that I understand whats wrong with my code

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with the help of the error message, I'm going to fix it.

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I just need to put the semi-colon

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back at the end of that line

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and now I should be able to compile

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the code and it compiles with no syntax errors.