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How would you go about this reflection task in Groovy:
(1) provide a class type to the Groovy function
(2) loop over all the methods of this class
(a) print out each parameter name and type from the method
(b) print out the return type
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Overview. Method Parameter Reflection support was added in Java 8. Simply put, it provides support for getting the names of parameters at runtime. In this quick tutorial, we'll take a look at how to access parameter names for constructors and methods at runtime – using reflection.
You can obtain the names of the formal parameters of any method or constructor with the method java. lang. reflect.
In order to reflect a Java class, we first need to create an object of Class . And, using the object we can call various methods to get information about methods, fields, and constructors present in a class. class Dog {...} // create object of Class // to reflect the Dog class Class a = Class. forName("Dog");
I think the best you can do is to write something like this:
def dumpOut( clz ) {
clz.metaClass.methods.each { method ->
println "${method.returnType.name} ${method.name}( ${method.parameterTypes*.name.join( ', ' )} )"
}
}
dumpOut String.class
Which will print out:
boolean equals( java.lang.Object )
java.lang.Class getClass( )
int hashCode( )
void notify( )
void notifyAll( )
java.lang.String toString( )
void wait( )
void wait( long )
void wait( long, int )
char charAt( int )
int codePointAt( int )
int codePointBefore( int )
int codePointCount( int, int )
int compareTo( java.lang.Object )
int compareTo( java.lang.String )
int compareToIgnoreCase( java.lang.String )
java.lang.String concat( java.lang.String )
boolean contains( java.lang.CharSequence )
boolean contentEquals( java.lang.CharSequence )
boolean contentEquals( java.lang.StringBuffer )
java.lang.String copyValueOf( [C )
java.lang.String copyValueOf( [C, int, int )
boolean endsWith( java.lang.String )
boolean equals( java.lang.Object )
boolean equalsIgnoreCase( java.lang.String )
java.lang.String format( java.lang.String, [Ljava.lang.Object; )
java.lang.String format( java.util.Locale, java.lang.String, [Ljava.lang.Object; )
[B getBytes( )
[B getBytes( java.lang.String )
[B getBytes( java.nio.charset.Charset )
void getBytes( int, int, [B, int )
void getChars( int, int, [C, int )
int hashCode( )
int indexOf( int )
int indexOf( java.lang.String )
int indexOf( int, int )
int indexOf( java.lang.String, int )
java.lang.String intern( )
boolean isEmpty( )
int lastIndexOf( int )
int lastIndexOf( java.lang.String )
int lastIndexOf( int, int )
int lastIndexOf( java.lang.String, int )
int length( )
boolean matches( java.lang.String )
int offsetByCodePoints( int, int )
boolean regionMatches( int, java.lang.String, int, int )
boolean regionMatches( boolean, int, java.lang.String, int, int )
java.lang.String replace( char, char )
java.lang.String replace( java.lang.CharSequence, java.lang.CharSequence )
java.lang.String replaceAll( java.lang.String, java.lang.String )
java.lang.String replaceFirst( java.lang.String, java.lang.String )
[Ljava.lang.String; split( java.lang.String )
[Ljava.lang.String; split( java.lang.String, int )
boolean startsWith( java.lang.String )
boolean startsWith( java.lang.String, int )
java.lang.CharSequence subSequence( int, int )
java.lang.String substring( int )
java.lang.String substring( int, int )
[C toCharArray( )
java.lang.String toLowerCase( )
java.lang.String toLowerCase( java.util.Locale )
java.lang.String toString( )
java.lang.String toUpperCase( )
java.lang.String toUpperCase( java.util.Locale )
java.lang.String trim( )
java.lang.String valueOf( [C )
java.lang.String valueOf( boolean )
java.lang.String valueOf( char )
java.lang.String valueOf( double )
java.lang.String valueOf( float )
java.lang.String valueOf( int )
java.lang.String valueOf( java.lang.Object )
java.lang.String valueOf( long )
java.lang.String valueOf( [C, int, int )
I think parameter names are not possible without manipulating the bytecode (and assuming the class was compiled with this sort of debug information intact)
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