1.
          If operators with the same precedence are next to each other, there associativity determines the order of evaluation. All binary operators except assignment operators are left-associative.
          Assignment operators are right-associative. Therefore, the expression
          a = b += c = 5 equivalent a = (b += (c = 5))

          If no operands hava side effects that change the value of a variable, the order of operand evaluation is irrelevant. Interesting cases arise when operands do hava a side effect. For example,

          public class TestDemo {
          public static void main(String arg[]) {
          int a = 0;
          int x = ++a + a;
          System.out.println(x);
          a = 0;
          x = a + (++a);
          System.out.println(x);
          }
          }

          The output will be:
          2
          1

          The order for evaluation operands takes precedence over the operator precedence rule. In the former case, (++a) has higher precedence than addition (+), but since a is a left-hand operand of the addition (+), it is evaluated before any part of its right-hand operand (e.g., ++a in this case).

          2.
          Converting Strings to Numbers:
          int intValue = Integer.parseInt(intString);
          double doubleValue = Double.parseDouble(doubleString);

          parseInt

          public static int parseInt(String s)
          throws NumberFormatException
          
          Parses the string argument as a signed decimal integer. The characters in the string must all be decimal digits, except that the first character may be an ASCII minus sign '-' ('\u002D') to indicate a negative value. The resulting integer value is returned, exactly as if the argument and the radix 10 were given as arguments to the parseInt(java.lang.String, int) method.
          Parameters:
          s - a String containing the int representation to be parsed
          Returns:
          the integer value represented by the argument in decimal.
          Throws:

          NumberFormatException - if the string does not contain a parsable integer.

          3.
          Format to keep two digits after the decimal point:
          double doubleValue = (int)(doubleValue2 * 100) / 100.0

          4.
          Computing ab:
          public static double pow(double a, double b)


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          1.21 Java notes

          Posted on 2007-04-22 20:22 ZelluX 閱讀(140) 評論(0)  編輯  收藏 所屬分類: OOP
          2007-01-21 21:57:20
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