30 lines
778 B
Java
30 lines
778 B
Java
public class Accumulator
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//implements java.util.function.UnaryOperator<Number> // Java 8
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{
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private Number sum;
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public Accumulator(Number sum0) {
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sum = sum0;
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}
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public Number apply(Number n) {
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// Acts like sum += n, but chooses long or double.
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// Converts weird types (like BigInteger) to double.
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return (longable(sum) && longable(n)) ?
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(sum = sum.longValue() + n.longValue()) :
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(sum = sum.doubleValue() + n.doubleValue());
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}
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private static boolean longable(Number n) {
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return n instanceof Byte || n instanceof Short ||
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n instanceof Integer || n instanceof Long;
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}
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public static void main(String[] args) {
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Accumulator x = new Accumulator(1);
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x.apply(5);
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new Accumulator(3);
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System.out.println(x.apply(2.3));
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}
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}
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