I need to compare two double values with relation type as string. Eg:
String relation = "<=";
double aAA=5.9,bBB=6.999999;
In the above example need to compare aAA relation bBB using java
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`if (relation.equals("<=") { comparisonResult = a <= b; }` – JB Nizet Jan 06 '18 at 14:49
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A lot more background information and your own code attempts would help to greatly clarify this question/problem. – Hovercraft Full Of Eels Jan 06 '18 at 14:51
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if I have list of relation is there like<=,>=,<,><,,== then I need many conditions. – Shiva Goud A Jan 06 '18 at 14:51
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1this answer should help you https://stackoverflow.com/a/23493336/5558072 – Youcef LAIDANI Jan 06 '18 at 14:52
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1You need 5. 5 is far from being many. – JB Nizet Jan 06 '18 at 14:56
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There is no built-in way of parsing `<=` as you desire. You will need to **map it** manually or use technologies that can **parse it**. Typical *eval* functions could do the trick, for example by using Javas built-in JavaScript interpreter. – Zabuzard Jan 06 '18 at 16:19
1 Answers
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You could create a Map mapping the Strings to the actual operations, e.g. as BiPredicate.
Map<String, BiPredicate<Double, Double>> relations = new HashMap<>();
relations.put("<=", (a, b) -> a <= b);
relations.put(">=", (a, b) -> a >= b);
relations.put("==", (a, b) -> a == b);
// ...
String relation = "<=";
double aAA=5.9,bBB=6.999999;
boolean result = relations.get(relation).test(aAA, bBB);
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I like the use of `BiPredicate`, makes the code pretty compact and readable. – Zabuzard Jan 06 '18 at 16:20