Java Reference
In-Depth Information
public static String arrayListToString(ArrayList<String> list, String saparator) {
String[] tempArray = new String[list.size()];
tempArray = list.toArray(tempArray);
String str = String.join(saparator, tempArray);
return str;
}
}
Reflecting on Methods
The following four methods in the
Class
class can be used to get information about the methods of a class:
Method[] getMethods()
•
Method[] getDeclaredMethods()
•
Method getMethod(String name, Class... parameterTypes)
•
Method getDeclaredMethod(String name, Class... parameterTypes)
•
The
getMethods()
method returns all the accessible public methods of the class. The accessible public methods
include any public method declared in the class or inherited from the superclass. The
getDeclaredMethods()
method returns all the methods declared only in the class. It does not return any methods that are inherited from the
superclass. The other two methods,
getMethod()
and
getDeclaredMethod()
, are used to get the
Method
object if you
know the name of the method and its parameter types.
The
getReturnType()
method of the Method class returns the
Class
object, which contains information about
the return type of the method.
Listing 3-7 illustrates how to get information about the methods of a class. You can uncomment the code in
the
main()
method to print all methods in the
Person
class—declared in the
Person
class and inherited from the
Object
class.
Listing 3-7.
Reflecting on Methods of a Class
// MethodReflection.java
package com.jdojo.reflection;
import java.lang.reflect.Method;
import java.util.ArrayList;
public class MethodReflection {
public static void main(String[] args) {
Class<Person> c = Person.class;
// Get the declared methods
ArrayList<String> methodsDesciption = getDeclaredMethodsList(c);
System.out.println("Declared Methods for " + c.getName());
for (String desc : methodsDesciption) {
System.out.println(desc);
}
