In a previous job, I was working in C++, and the company internal library had a logging macro where I could simply write LOG(somevariable), and it would output to standard out:
"variablename: variablevalue"
Does anyone know if there's a way to do this in Java?
I never thought to look at their code so I don't know how it was done. It was really useful though!
If you use Eclipse you can use the "Watch Expression"-View to watch not only variables but also Method calls. See this.
If you just want to print a variable's value, you can use an Eclipse Template.
Go to Windows->Preferences and look for the entry Java->Editor->Templates. Add a new template and call it for example "printvar". Add the following to the templates body:
System.out.println("${variable} = "+ ${variable});
Typing printvar during coding and then pressing CTRL+Space will generate the entered code using ${variable} as placeholder for the variable name. You will have to type the variable name only once, which saves time and typing.
BTW: The reason why you can create macros permitting syntactic sugar like LOG(variable_name) in C++, is beacuse C++ has a preprocessor: Java has none. There are implementations for Java preprocessors, but I think using one would be too much effort for such a simple problem like printing a variable's name followed by its value.
If you type soutv + TAB on Intellij and Netbeans it will give you a list of variables you might want to print.
I copied this and changed it to use the logger instead with logv + TAB
The typical technique is to use log4j, or logback, or something. Perhaps as mediated by slf4j. This required, typically, a static variable per class, which in turn causes the log messages to tell you where they are coming from.
You don't have MACRO's in java, but you could do something like this with a static method on some class.. does not have the variable name but does have the class type.
class DebugUtil
{
public void static LOG(Object obj)
{
LOG(System.out, obj.getClass().getName(), obj);
}
public void static LOG(String name, Object obj)
{
LOG(System.out, name, obj);
}
public void static LOG(PrintStream ps, String name, Object obj)
{
ps.println(name + ":" + obj);
}
}
then for usage
String foo = "bar";
Debug.Util.LOG(foo);
Debug.Util.LOG("foo", foo);
soutv+ TAB to generate a println statement that will do that.