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Published byMichael Phillips Modified over 9 years ago
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[ ] Questions [ ] Lab / HW Notes [ ] try/catch blocks – keep control [ ] Notes - Documentation – what was changed - names – single characters –no sentenceAnalysis and all other methods - String is capitalized, double is not - method parameter list - method signature [ ] what is an object? Book, chair, freshman ap, student, classroom, biographical info
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[ ] Lab / HW Notes - Loop endpoints are killers - Index out of range exception --- charAt(0) - In a for loop, DO NOT MUCK WITH THE INDEX - No single letter variable names (convention??) - total += count; what does this do? total = total + count; - Initialize all variables when declared - Study together – doing this class by yourself is really difficult - Ask questions
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Java throws exceptions all over the place That’s good news – java is trying to help take care of us. So what tools can we use to maintain control? That’s really the issue – maintain control of your programs. If we try something and it works fine – great, no worry But if we try something and it blows up, we would like to be able to recover so we are not embarrassed
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What could possibly go wrong? “Please enter an integer:” $ oh man!! What is the 4 th character of String S1 = “Hi!”; Well, it is S1.charAt(3) oh man!! The first is an InputMismatchException The second is an IndexOutOfBoundsException Why??? On both?
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Help us out java: try { something if it works – great, continue on } catch (Exception somevariablename) { here’s our chance to avoid losing control – we catch the exception that java throws and handle it the way we want. } … java program continues
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Examples ------ see links on our web page tryCatch2.java tryCatch3.java tryCatch4.java Trouble in River City Trouble in River City – the reason for try/catch blocks
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for ( ; ; ) { } Pre-condition loop loop-controlled What is the ‘for-body’ Is the index automatically incremented? When? What goes in all the blank areas?
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for ( starting index ;logical expression; index mover) { for body index++ } The ‘index mover’ is implicit – automatically done on way up. Note: DO NOT MUCK WITH AN INDEX
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for ( int index = 0; index < 5; index++) { System.out.prinln(“hello!”); } Hand trace Output
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Images --- METHOD
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// Pre: type1, type2 // Post: retobty (type of returned object) public static retobty mName(type1 name1, type2 name2) { method body } Method signature mName: type1, type2
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Images --- Scanner
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Images --- Scanner
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Images --- Scanner
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- Do not get paralyzed - Draw a picture - Write a story - What is the concept? - The helicopter perspective? Who’s in control – you or the CA?
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