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2010-05-31T17:44:26Z

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== Demonstrate Package ==



<source lang="java">
class PkgTest {
public static void main(String args[]) {
Package pkgs[];

pkgs = Package.getPackages();

for(int i=0; i < pkgs.length; i++)
System.out.println(
pkgs[i].getName() + " " +
pkgs[i].getImplementationTitle() + " " +
pkgs[i].getImplementationVendor() + " " +
pkgs[i].getImplementationVersion()
);

}
}</source>



== Detect if a package is available ==



<source lang="java">
public class Main{
public static void main(String args[]) {
System.out.println(isAvailable("javax.swing.JComponent"));
}
public static boolean isAvailable(String className) {
boolean isFound = false;
try {
Class.forName(className, false, null);
isFound = true;
}
catch (ClassNotFoundException e) {
isFound = false;
}
return isFound;
}
}</source>



== Find the Package of an Object ==



<source lang="java">
import java.util.ArrayList;
import java.util.Vector;
public class Main {
public static void main(String[] args) {
System.out.println(new Vector().getClass().getPackage().getName());
System.out.println(new ArrayList().getClass().getPackage().getName());
System.out.println("Test String".getClass().getPackage().getName());
System.out.println(new Integer(1).getClass().getPackage().getName());
}
}
/*
java.util
java.util
java.lang
java.lang
*/</source>



== Get full package name ==



<source lang="java">
public class Main {
public static String getPackageName(Class c) {
String fullyQualifiedName = c.getName();
int lastDot = fullyQualifiedName.lastIndexOf(".");
if (lastDot == -1) {
return "";
}
return fullyQualifiedName.substring(0, lastDot);
}
public static void main(String[] args) {
System.out.println(getPackageName(java.awt.Frame.class));
}
}</source>



== Get non Package Qualified Name ==



<source lang="java">
public class Utils {
public static String nonPackageQualifiedName( final Class<?> clazz ) {
String name = clazz.getName();
return name.substring(name.lastIndexOf(".") + 1);
}

}</source>



== Get package name of a class ==



<source lang="java">
import java.util.Date;
public class Main {
public static void main(String[] args) {
Date date = new Date();
Package pack = date.getClass().getPackage();
String packageName = pack.getName();
System.out.println("Package Name = " + packageName);
}
}</source>



== Get Package Names From Dir ==



<source lang="java">
/**
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
*/
import java.io.File;
import java.util.List;
public final class ReflectionUtil {
private static void getPackageNamesFromDir(File base, File dir, List<String> pkgs) {
boolean foundClass = false;
for (File file : dir.listFiles()) {
if (file.isDirectory()) {
getPackageNamesFromDir(base, file, pkgs);
} else if (!foundClass && file.getName().endsWith(".class")) {
foundClass = true;
String pkg = "";
file = dir;
while (!file.equals(base)) {
if (!"".equals(pkg)) {
pkg = "." + pkg;
}
pkg = file.getName() + pkg;
file = file.getParentFile();
}
if (!pkgs.contains(pkg)) {
pkgs.add(pkg);
}
}
}
}
private static String getPackageName(String clzName) {
if (clzName.indexOf("/") == -1) {
return null;
}
String packageName = clzName.substring(0, clzName.lastIndexOf("/"));
return packageName.replace("/", ".");
}
}</source>



== getPackage() returns null for a class in the unnamed package ==



<source lang="java">
public class Main {
public static void main(String[] argv) throws Exception {
Class cls = MyClass.class;
Package pkg = cls.getPackage(); // null
}
}
class MyClass{}</source>



== getPackage() returns null for a primitive type or array ==



<source lang="java">
public class Main {
public static void main(String[] argv) throws Exception {
Package pkg = int.class.getPackage(); // null
pkg = int[].class.getPackage(); // null
}
}</source>



== Get the class name with or without the package ==



<source lang="java">
public class Main {
public static String getClassName(Class c) {
String className = c.getName();
int firstChar;
firstChar = className.lastIndexOf(".") + 1;
if (firstChar > 0) {
className = className.substring(firstChar);
}
return className;
}

public static void main(String[] args) {
System.out.println(getClassName(java.awt.Frame.class));
}
}</source>



== Get the package name of the specified class. ==



<source lang="java">
import java.lang.reflect.Method;
import java.net.URL;
import java.security.CodeSource;
import java.security.ProtectionDomain;
import java.util.HashSet;
import java.util.List;
import java.util.Set;
/*
* JBoss, Home of Professional Open Source
* Copyright 2005, JBoss Inc., and individual contributors as indicated
* by the @authors tag. See the copyright.txt in the distribution for a
* full listing of individual contributors.
*
* This is free software; you can redistribute it and/or modify it
* under the terms of the GNU Lesser General Public License as
* published by the Free Software Foundation; either version 2.1 of
* the License, or (at your option) any later version.
*
* This software is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this software; if not, write to the Free
* Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
* 02110-1301 USA, or see the FSF site: http://www.fsf.org.
*/
public class Main {
/** The string used to separator packages */
public static final String PACKAGE_SEPARATOR = ".";
/**
* Get the package name of the specified class.
*
* @param classname
* Class name.
* @return Package name or "" if the classname is in the <i>default</i>
* package.
*
* @throws EmptyStringException
* Classname is an empty string.
*/
public static String getPackageName(final String classname) {
if (classname.length() == 0)
System.out.println("Empty String Exception");
int index = classname.lastIndexOf(PACKAGE_SEPARATOR);
if (index != -1)
return classname.substring(0, index);
return "";
}
}</source>



== Get the short name of the specified class by striping off the package name. ==



<source lang="java">
import java.lang.reflect.Method;
import java.net.URL;
import java.security.CodeSource;
import java.security.ProtectionDomain;
import java.util.HashSet;
import java.util.List;
import java.util.Set;
/*
* JBoss, Home of Professional Open Source
* Copyright 2005, JBoss Inc., and individual contributors as indicated
* by the @authors tag. See the copyright.txt in the distribution for a
* full listing of individual contributors.
*
* This is free software; you can redistribute it and/or modify it
* under the terms of the GNU Lesser General Public License as
* published by the Free Software Foundation; either version 2.1 of
* the License, or (at your option) any later version.
*
* This software is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this software; if not, write to the Free
* Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
* 02110-1301 USA, or see the FSF site: http://www.fsf.org.
*/
public class Main {
/** The string used to separator packages */
public static final String PACKAGE_SEPARATOR = ".";
/**
* Get the short name of the specified class by striping off the package name.
*
* @param classname
* Class name.
* @return Short class name.
*/
public static String stripPackageName(final String classname) {
int idx = classname.lastIndexOf(PACKAGE_SEPARATOR);
if (idx != -1)
return classname.substring(idx + 1, classname.length());
return classname;
}
}</source>



== Returns the package portion of the specified class ==



<source lang="java">
public class Utils {
/**
* Returns the package portion of the specified class
* @param className the name of the class from which to extract the package
* @return package portion of the specified class
*/
public static String getPackageName(final String className) {
if (className != null) {
final int index = className.lastIndexOf(".");
return ((index != -1) ? className.substring(0, index) : ""); // NOI18N
}
return null;
}
}</source>

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в 17:44, 31 мая 2010

Admin: 1 версия