Change non-void method's parameters.

What is the best way to change a non-void method's parameters WITHOUT instancing a new one..
For example

class ReadStdout{

    public ReadStdout(Process p, JTextArea c){
           (....)
    }
}

then on the main constructor

ReadStdout read = new ReadStdout(process, console);

and then when a method is called, in a button listener perhaps, ReadStdout() should have new parameters.

I was thinking something like,

read.ReadStdout(newprocess, newconsole);

But doesn't work..

Any help would greatly appreciated.
Thank you.