Java review note


Abstraction:

  • Big programs are built out of small methods.
  • Methods can be individually developed,tested and reused.
  • User of method does not need to know how it works.

Good programming style

  • Rule 1: Use good(meaningful) names

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    String a1;
    int a2;
    double b; // BAD!!
    String firstName; // GOOD String lastName; // GOOD int temperature; // GOOD
  • Rule 2: Use indentation

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    public static void main (String[] arguments) { int x = 5;
    x = x * x;
    if (x > 20) {
    System.out.println(x + “ is greater than 20.”); }
    double y = 3.4; }

Ctrl-shift-F to auto-format the file

  • Rule 3:Use whitespaces
    Put whitespaces in complex expressions:

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    // BAD!!
    double cel=fahr*42.0/(13.0-7.0);
    // GOOD
    double cel = fahr * 42.0 / (13.0 - 7.0);
  • Rule 4:Do not duplicate tests

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    if (basePay < 8.0) { ...
    } else if (hours > 60) { ...
    } else if (basePay >= 8.0 && hours <= 60){ ...
    }

—————–BAD—————–

Something about loop

  • break: terminates a for a while loop
    break

  • continue: skips the current iteration of a loop and preceeds directly to the next iteration.
    continue


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