Java Reflection: How to Get the Name of a Variable

Java Reflection: How to get the name of a variable?

As of Java 8, some local variable name information is available through reflection. See the "Update" section below.

Complete information is often stored in class files. One compile-time optimization is to remove it, saving space (and providing some obsfuscation). However, when it is is present, each method has a local variable table attribute that lists the type and name of local variables, and the range of instructions where they are in scope.

Perhaps a byte-code engineering library like ASM would allow you to inspect this information at runtime. The only reasonable place I can think of for needing this information is in a development tool, and so byte-code engineering is likely to be useful for other purposes too.

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Update: Limited support for this was added to Java 8. Parameter (a special class of local variable) names are now available via reflection. Among other purposes, this can help to replace @ParameterName annotations used by dependency injection containers.

How to get variable name? - java

You can get all field name by reflection

Class yourClass = YourClass.class
Field[] fields = yourClass.getFields();
for(Field f: fields){
    f.getName();
}

or if you want mapping then go for Map

Map<String, String> propertyToValueMap

if you are trying to read method's local variable name, then it is not that simple to fetch also a signal that you are doing something wrong

Getting a variable by name using reflection in Java

You get a field

field = getClass().getDeclaredField(name);

on whatever whatever type this is, presumably com.whatever.project.Hexagon. But then you try to retrieve the field on an object of type com.badlogic.gdx.graphics.Color.

System.out.println(field.get(c));

This is wrong. The javadoc states

Returns the value of the field represented by this Field, on the
specified object.

Color does not have a Color field.

What you want is probably

field.get(this)

Get all variable names in a class

Field[] fields = YourClassName.class.getFields();

returns an array of all public variables of the class.

getFields() return the fields in the whole class-heirarcy. If you want to have the fields defined only in the class in question, and not its superclasses, use getDeclaredFields(), and filter the public ones with the following Modifier approach:

Modifier.isPublic(field.getModifiers());

The YourClassName.class literal actually represents an object of type java.lang.Class. Check its docs for more interesting reflection methods.

The Field class above is java.lang.reflect.Field. You may take a look at the whole java.lang.reflect package.

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