Re: Variable in Setter

From:
Joshua Cranmer <Pidgeot18@verizon.net>
Newsgroups:
comp.lang.java.programmer
Date:
Sat, 11 Aug 2007 02:32:42 GMT
Message-ID:
<ed9vi.35$vC4.13@trndny01>
teser3@hotmail.com wrote:

I have this:
BeanChalker.setLastname(lastname);

Is it possible to use variables like this because I am not sure how to
set up the variable or use concatenator some way to make it work:

String myvariableOne = "Lastname";
String myvariableTwo = "lastname";
BeanChalker.set + myvariableOne + (myvariableTwo);


If I understand you correctly, what you want is a runtime method
dispatch. The short answer to your question is "no it is not possible."
The medium answer is "well, yes it is, but it is generally not a good
idea to try and use."

The easiest way to do what you want to do is to manually set functions
up yourself:

class Foo {
    private String varA, varB, varC;
    // constructors, etc.

    public void setA(String newA) {varA = newA;}
    public void setB(String newB) {varB = newB;}
    public void setC(String newC) {varC = newC;}

    public void set(String variable, String value) {
        if ("A".equals(variable))
            setA(value);
        else if ("B".equals(variable))
            setB(value);
        else if ("C".equals(variable))
            setC(value);
        else
            throw new IllegalArgumentException("Variable "+variable+
                " not found!");
    }
}

If you really want the long answer, you probably don't. Use the previous
solution if at all feasible or not at all.

Still want it? Here's the reflection method:

class Foo { /* Defined similar to above sample, except w/o set */ }

class Test {
     public void foobar() {
         String variable = "Lastname";
         String value = "Stroustrup"; // Kudos if you get the reference!
         Foo bar = new Foo(); // assume it works

         Class<?> fooClass = Foo.class;
         try {
            Method m = fooClass.getMethod("set"+variable);
            m.invoke(bar,value);
         } catch (Exception e) { // See the APIs for all exceptions
             // Don't do this in real code.
         }
     }
}

I don't recommend that approach.
--
Beware of bugs in the above code; I have only proved it correct, not
tried it. -- Donald E. Knuth

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