124 lines
3.5 KiB
Java
124 lines
3.5 KiB
Java
package genericReflection;
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import java.lang.reflect.*;
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import java.util.*;
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/**
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* @version 1.10 2007-05-15
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* @author Cay Horstmann
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*/
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public class GenericReflectionTest
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{
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public static void main(String[] args)
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{
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// read class name from command line args or user input
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String name;
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if (args.length > 0) name = args[0];
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else
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{
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try (Scanner in = new Scanner(System.in))
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{
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System.out.println("Enter class name (e.g. java.util.Collections): ");
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name = in.next();
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}
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}
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try
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{
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// print generic info for class and public methods
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Class<?> cl = Class.forName(name);
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printClass(cl);
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for (Method m : cl.getDeclaredMethods())
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printMethod(m);
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}
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catch (ClassNotFoundException e)
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{
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e.printStackTrace();
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}
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}
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public static void printClass(Class<?> cl)
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{
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System.out.print(cl);
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printTypes(cl.getTypeParameters(), "<", ", ", ">", true);
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Type sc = cl.getGenericSuperclass();
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if (sc != null)
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{
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System.out.print(" extends ");
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printType(sc, false);
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}
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printTypes(cl.getGenericInterfaces(), " implements ", ", ", "", false);
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System.out.println();
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}
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public static void printMethod(Method m)
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{
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String name = m.getName();
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System.out.print(Modifier.toString(m.getModifiers()));
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System.out.print(" ");
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printTypes(m.getTypeParameters(), "<", ", ", "> ", true);
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printType(m.getGenericReturnType(), false);
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System.out.print(" ");
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System.out.print(name);
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System.out.print("(");
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printTypes(m.getGenericParameterTypes(), "", ", ", "", false);
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System.out.println(")");
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}
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public static void printTypes(Type[] types, String pre, String sep, String suf,
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boolean isDefinition)
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{
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if (pre.equals(" extends ") && Arrays.equals(types, new Type[] { Object.class })) return;
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if (types.length > 0) System.out.print(pre);
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for (int i = 0; i < types.length; i++)
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{
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if (i > 0) System.out.print(sep);
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printType(types[i], isDefinition);
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}
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if (types.length > 0) System.out.print(suf);
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}
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public static void printType(Type type, boolean isDefinition)
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{
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if (type instanceof Class)
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{
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Class<?> t = (Class<?>) type;
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System.out.print(t.getName());
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}
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else if (type instanceof TypeVariable)
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{
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TypeVariable<?> t = (TypeVariable<?>) type;
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System.out.print(t.getName());
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if (isDefinition)
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printTypes(t.getBounds(), " extends ", " & ", "", false);
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}
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else if (type instanceof WildcardType)
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{
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WildcardType t = (WildcardType) type;
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System.out.print("?");
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printTypes(t.getUpperBounds(), " extends ", " & ", "", false);
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printTypes(t.getLowerBounds(), " super ", " & ", "", false);
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}
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else if (type instanceof ParameterizedType)
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{
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ParameterizedType t = (ParameterizedType) type;
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Type owner = t.getOwnerType();
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if (owner != null)
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{
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printType(owner, false);
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System.out.print(".");
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}
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printType(t.getRawType(), false);
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printTypes(t.getActualTypeArguments(), "<", ", ", ">", false);
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}
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else if (type instanceof GenericArrayType)
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{
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GenericArrayType t = (GenericArrayType) type;
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System.out.print("");
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printType(t.getGenericComponentType(), isDefinition);
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System.out.print("[]");
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}
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}
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}
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