I have the following class:
public class Test {
public static int a = 0;
public int b = 1;
}
Is it possible to use reflection to get a list of the static fields only? I'm aware I can get an array of all the fields with Test.class.getDeclaredFields(). But it seems there's no way to determine if a Field instance represents a static field or not.
You can do it like this:
Field[] declaredFields = Test.class.getDeclaredFields();
List<Field> staticFields = new ArrayList<Field>();
for (Field field : declaredFields) {
if (java.lang.reflect.Modifier.isStatic(field.getModifiers())) {
staticFields.add(field);
}
}
I stumbled across this question by accident and felt it needed a Java 8 update using streams:
public static List<Field> getStatics(Class<?> clazz) {
List<Field> result;
result = Arrays.stream(clazz.getDeclaredFields())
// filter out the non-static fields
.filter(f -> Modifier.isStatic(f.getModifiers()))
// collect to list
.collect(toList());
return result;
}
Obviously, that sample is a bit embelished for readability. In actually, you would likely write it like this:
public static List<Field> getStatics(Class<?> clazz) {
return Arrays.stream(clazz.getDeclaredFields()).filter(f ->
Modifier.isStatic(f.getModifiers())).collect(toList());
}
Thats Simple , you can use Modifier to check if a field is static or not. Here is a sample code for that kind of task.
public static void printModifiers(Object o) {
Class c = o.getClass();
int m = c.getModifiers();
if (Modifier.isPublic(m))
System.out.println ("public");
if (Modifier.isAbstract(m))
System.out.println ("abstract");
if (Modifier.isFinal(m))
System.out.println ("final");
if(Modifier.isStatic(m))
System.out.println("static");
}
If you can add open-source dependencies to your project you can also use FieldUtils.readDeclaredStaticField(Test.class,"a")
