52 lines
1.8 KiB
Java
52 lines
1.8 KiB
Java
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DOS Calculator
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public class Calculator {
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public static abstract class Operation {
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private final String name;
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Operation(String name) { this.name = name; }
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public String toString() { return this.name; }
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// Perform arithmetic op represented by this constant
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abstract double eval(double x, double y);
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// Doubly nested anonymous classes
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public static final Operation PLUS = new Operation("+") {
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double eval(double x, double y) { return x + y; }
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};
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public static final Operation MINUS = new Operation("-") {
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double eval(double x, double y) { return x - y; }
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};
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public static final Operation TIMES = new Operation("*") {
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double eval(double x, double y) { return x * y; }
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};
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public static final Operation DIVIDE = new Operation("/") {
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double eval(double x, double y) { return x / y; }
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};
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}
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// Return the results of the specified calculation
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public double calculate(double x, Operation op, double y) {
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return op.eval(x, y);
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}
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}
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public class CalcTest {
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public static void main(String args[]) {
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double x = Double.parseDouble(args[0]);
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double y = Double.parseDouble(args[1]);
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operate(x, Calculator.Operation.PLUS, y);
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operate(x, Calculator.Operation.MINUS, y);
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operate(x, Calculator.Operation.TIMES, y);
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operate(x, Calculator.Operation.DIVIDE, y);
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}
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static void operate(double x, Calculator.Operation op, double y) {
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Calculator c = new Calculator();
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System.out.println(x + " " + op + " " + y + " = " +
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c.calculate(x, op, y));
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}
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}
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