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Java Forum / First Aid / February 2005how to write a method to return 2 values
Hi to all, is it possible to write a method in Java such that it returns more than one values of different type each (i.e a boolean and an integer)?How this could be done? thanks in advance thanasis No, you can't have more than one thing returned from the method. You could encapsulate the two variables into an object and return the object. thanks > No, you can't have more than one thing returned from the method. You > could encapsulate the two variables into an object and return the > object. "Thanasis \(sch\)" <thanasis_gr@hotmail.com> scribbled on the stall wall: > Hi to all, > > is it possible to write a method in Java such that it returns more than one > values of different type each (i.e a boolean and an integer)?How this could > be done? As klynn74 mentioned: the way to do that is to make your method return an object of a class that contains the two variables. Another (ungracefull) way is to return an array of objects and type cast the returned objects to whatever native types they are suppose to be. Note that asking a method to return multiple values signifies to me a poor design. Think about why you feel that you need to do this and reevaluate. > Note that asking a method to return multiple values signifies to me a > poor design. Think about why you feel that you need to do this and > reevaluate. See java.math.BigInteger#divideAndRemainder() for an example of a single computation that produces two outputs.  SignatureEric.Sosman@sun.com >> is it possible to write a method in Java such that it returns more than one >> values of different type each (i.e a boolean and an integer)?How this >> could >> be done? thanks for reply. i am writing visualization software for graph algorithms and i need a method to accomplish 2 tasks: 1) given a graph's node i want my method to determine (yes/no) whether exists an unvisited adjacent node 2) return the leftmost unvisited adjacent node Having pascal programming background i think that the java design team must have predicted that situation :) wishes thanasis Thanasis (sch) wrote: > >> is it possible to write a method in Java such that it returns more than > one [quoted text clipped - 9 lines] > exists an unvisited adjacent node > 2) return the leftmost unvisited adjacent node How about /** Find the leftmost unvisited node adjacent to a * given node. * @param node The given node. * @returns The leftmost unvisited node adjacent * to <code>node</code>, or <code>null</code> * if no such node exists. */ Node leftmostUnvisitedAdjacent(Node node) { ... } ? Unless the graph can legitimately contain `null' nodes, this seems a natural approach. SignatureEric.Sosman@sun.com Eric Sosman <eric.sosman@sun.com> scribbled on the stall wall: > How about > [quoted text clipped - 9 lines] > ? Unless the graph can legitimately contain `null' nodes, > this seems a natural approach. I agree. With the purpose he outlines he doesn't really need two return values. Either your way, or having the method throw an exception for (no nodes found) would be more intuitive than a boolean status returned. > Eric Sosman <eric.sosman@sun.com> scribbled on the stall wall: > [quoted text clipped - 19 lines] > http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups > ----= East and West-Coast Server Farms - Total Privacy via Encryption =---- Of course. If you think about it, what would the node parameter return if the boolean returned false??? So there is clearly no reason to return two parameters. Paul. > How about > /** Find the leftmost unvisited node adjacent to a > * given node. [quoted text clipped - 7 lines] > ? Unless the graph can legitimately contain `null' nodes, > this seems a natural approach. hi eric, thanks again for reply. i had already found solution using 2 methods. One that finds out if an adjacent unvisited node exists and a second one that actually returns the leftmost adjacent unvisited node. I think your solution does work. regards thanasis Thanasis (sch) wrote: > > How about > [quoted text clipped - 20 lines] > regards > thanasis You do need to decide what the leftmost adjacent unvisited node method does when there is no such node. If there is a separate check method, the balance may shift in favor of treating it as an exception. Incidentally, there is another pattern that might be appropriate, depending on the wider context. Have you considered giving your structure the ability to return an iterator that visits the nodes in leftmost order? The java.util source code contains several implementation examples. Patricia > >> is it possible to write a method in Java such that it returns more than >one [quoted text clipped - 8 lines] >exists an unvisited adjacent node >2) return the leftmost unvisited adjacent node Return null if it doesn't exist and the leftmost node if it does? -- now with more cowbell Free MagazinesGet these publications absolutely FREE for up to 12 months. There are no hidden fees and no obligation. Simply choose a title, complete the application form and submit it. Read more ...
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