48 lines
1.4 KiB
Java
48 lines
1.4 KiB
Java
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// operators/DoubleEquivalence.java
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// (c)2021 MindView LLC: see Copyright.txt
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// We make no guarantees that this code is fit for any purpose.
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// Visit http://OnJava8.com for more book information.
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public class DoubleEquivalence {
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static void show(String desc, Double n1, Double n2) {
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System.out.println(desc + ":");
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System.out.printf(
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"%e==%e %b %b%n", n1, n2, n1 == n2, n1.equals(n2));
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}
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@SuppressWarnings("deprecation")
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public static void test(double x1, double x2) {
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// x1.equals(x2) // Won't compile
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System.out.printf("%e==%e %b%n", x1, x2, x1 == x2);
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Double d1 = x1;
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Double d2 = x2;
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show("Automatic", d1, d2);
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Double r1 = new Double(x1);
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Double r2 = new Double(x2);
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show("new Double()", r1, r2);
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Double v1 = Double.valueOf(x1);
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Double v2 = Double.valueOf(x2);
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show("Double.valueOf()", v1, v2);
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}
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public static void main(String[] args) {
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test(0, Double.MIN_VALUE);
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test(Double.MAX_VALUE,
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Double.MAX_VALUE - Double.MIN_VALUE * 1_000_000);
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}
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}
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/* Output:
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0.000000e+00==4.900000e-324 false
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Automatic:
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0.000000e+00==4.900000e-324 false false
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new Double():
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0.000000e+00==4.900000e-324 false false
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Double.valueOf():
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0.000000e+00==4.900000e-324 false false
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1.797693e+308==1.797693e+308 true
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Automatic:
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1.797693e+308==1.797693e+308 false true
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new Double():
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1.797693e+308==1.797693e+308 false true
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Double.valueOf():
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1.797693e+308==1.797693e+308 false true
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*/
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