In JAVA I want to create a Postfix and Prefix from an infix, but how do I tell JAVA to compare operators?

I am trying to take an infix expression such as a + b + c and turn it to postfix ab+c+ and prefix ++abc. I need to push them on the stack etc. While I worked out a method for stack pushing It depends on whether or not the operator is of a higher presidence or not than that one already on the top of the stack. The problem is that I don't know how to in JAVA compare operators. I did find some stuff such as this:





StackB x = new StackB ();


String op = "+-*/%^";


String post = "";





I wonder about the line:





String op = "+-*/%^";





Are they somehow using this so that the presidence is tested from left to right? Where they somehow make it so that + and - are equal and *, /, and % are equal? so for example since * is more to the right than + it has a higher presedence, again while somehow setting an equality between some of them, (+ and -, and *, /, and %). Does anyone have any idea how to distinguish between the presedences in JAVA?





Thanks,





Brian

In JAVA I want to create a Postfix and Prefix from an infix, but how do I tell JAVA to compare operators?
Operator precedence are already defined in java ...





surf through the link below ,this may help you


http://books.google.com/books?id=saj_wnV...





go to the page no 96-97-98 of this book





try to store all d operators in an array rather then a string ......

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