### Question:
SimpleDegree implements Degree { public Degree mul(Degree mul) { return new SimpleDegree( getValue()*mul.getValue() ); } SimpleDegree();  SimpleDegree(double degree);  SimpleDegree(String degree); void setValue(double value); double getValue(); int hashCode(); boolean equals(Object obj); Degree True(); Degree False(); Degree Unknown(); Degree sum(Degree sum); Degree mul(Degree mul); Degree div(Degree div); Degree sub(Degree sub); Degree neg(); Degree max(Degree comp); Degree min(Degree comp); Degree fromConst(double number); Degree fromString(String number); Degree fromBoolean(boolean val); static Degree fromBooleanLiteral( boolean val ); boolean toBoolean(); SimpleDegree asSimpleDegree(); String toString(); double getConfidence(); int compareTo(Degree arg0); IntervalDegree asIntervalDegree(); static final Degree TRUE; static final Degree FALSE; }### Answer:
@Test public void testMul() throws Exception { SimpleDegree s1 = new SimpleDegree(0.6); SimpleDegree s2 = new SimpleDegree(0.3); SimpleDegree s3 = new SimpleDegree(0.9); Degree s4 = s1.mul(s2); Degree s5 = s1.mul(s3); assertEquals(new SimpleDegree(0.6),s1); assertEquals(new SimpleDegree(0.3),s2); assertEquals(new SimpleDegree(0.9),s3); assertEquals(new SimpleDegree(0.18),s4); assertEquals(new SimpleDegree(0.54),s5); }