Mega Code Archive
String search and reflection helper methods
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/**
* The utillib library.
* More information is available at http://www.jinchess.com/.
* Copyright (C) 2002, 2003 Alexander Maryanovsky.
* All rights reserved.
*
* The utillib library 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 of the
* License, or (at your option) any later version.
*
* The utillib library 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 utillib library; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307, USA
*/
import java.util.Hashtable;
import java.util.Enumeration;
import java.util.NoSuchElementException;
/**
* A collection of general utility methods.
*/
public class Utilities{
/**
* A 0-length Object array.
*/
public static final Object [] EMPTY_ARRAY = new Object[0];
/**
* A 0-length long array.
*/
public static final long [] EMPTY_LONG_ARRAY = new long[0];
/**
* A 0-length int array.
*/
public static final int [] EMPTY_INT_ARRAY = new int[0];
/**
* A 0-length short array.
*/
public static final short [] EMPTY_SHORT_ARRAY = new short[0];
/**
* A 0-length byte array.
*/
public static final byte [] EMPTY_BYTE_ARRAY = new byte[0];
/**
* A 0-length char array.
*/
public static final char [] EMPTY_CHAR_ARRAY = new char[0];
/**
* A 0-length double array.
*/
public static final double [] EMPTY_DOUBLE_ARRAY = new double[0];
/**
* A 0-length float array.
*/
public static final float [] EMPTY_FLOAT_ARRAY = new float[0];
/**
* A 0-length String array.
*/
public static final String [] EMPTY_STRING_ARRAY = new String[0];
/**
* An empty enumeration.
*/
public static final Enumeration EMPTY_ENUM = new Enumeration(){
public boolean hasMoreElements(){return false;}
public Object nextElement(){throw new NoSuchElementException();}
};
/**
* Returns <code>true</code> if the two specified objects are the same.
* Returns <code>false</code> otherwise. To be considered the same, the two
* references must either both be null or invoking <code>equals</code> on one
* of them with the other must return <code>true</code>.
*/
public static boolean areEqual(Object obj1, Object obj2){
return (obj1 == obj2) || (obj1 == null ? false : obj1.equals(obj2));
}
/**
* Maps the specified key to the specified value in the specified
* <code>Hashtable</code>. If the specified value is <code>null</code> any
* existing mapping of the specified key is removed from the
* <code>Hashtable</code>. The old value mapped to the specified key
* is returned, or <code>null</code> if no value was mapped to the key.
*/
public static Object put(Hashtable table, Object key, Object value){
return value == null ? table.remove(key) : table.put(key, value);
}
/**
* Returns <code>true</code> if the specified object is an element of the
* specified array. The specified array may not be <code>null</code>. The
* specified object may be <code>null</code>, in which case this method will
* return <code>true</code> iff one of the indices in the array is empty
* (contains <code>null</code>).
*/
public static boolean contains(Object [] array, Object item){
return (indexOf(array, item) != -1);
}
/**
* Returns the index of the first occurrance of specified object in the
* specified array, or -1 if the specified object is not an element of the
* specified array. The specified object may be <code>null</code> in which
* case the returned index will be the index of the first <code>null</code>
* in the array.
*/
public static int indexOf(Object [] array, Object item){
if (array == null)
throw new IllegalArgumentException("The specified array may not be null");
for (int i = 0; i < array.length; i++)
if (areEqual(item, array[i]))
return i;
return -1;
}
/**
* Returns the index of the first occurrance of specified integer in the
* specified array, or -1 if the specified integer is not an element of the
* specified array.
*/
public static int indexOf(int [] arr, int val){
if (arr == null)
throw new IllegalArgumentException("The specified array may not be null");
for (int i = 0; i < arr.length; i++)
if (arr[i] == val)
return i;
return -1;
}
/**
* Converts the specified array into a string by appending all its elements
* separated by a semicolon.
*/
public static String arrayToString(Object [] arr){
StringBuffer buf = new StringBuffer();
for (int i = 0; i < arr.length; i++){
buf.append(arr[i]);
buf.append("; ");
}
if (arr.length > 0)
buf.setLength(buf.length() - 2); // get rid of the extra "; "
return buf.toString();
}
/**
* Converts the specified <code>Hashtable</code> into a string by putting
* each key and value on a separate line (separated by '\n') and an arrow
* (" -> ") between them.
*/
public static String hashtableToString(Hashtable hashtable){
StringBuffer buf = new StringBuffer();
Enumeration keys = hashtable.keys();
while (keys.hasMoreElements()){
Object key = keys.nextElement();
Object value = hashtable.get(key);
buf.append(key.toString());
buf.append(" -> ");
buf.append(value.toString());
buf.append("\n");
}
return buf.toString();
}
/**
* Returns the maximum element in the specified integer array.
*/
public static int max(int [] arr){
if (arr == null)
throw new IllegalArgumentException("The specified array may not be null");
if (arr.length == 0)
throw new IllegalArgumentException("The specified array must have at least one element");
int n = arr[0];
for (int i = 1; i < arr.length; i++)
if (arr[i] > n)
n = arr[i];
return n;
}
/**
* Returns a hash code for the specified double value.
*/
public static int hashCode(double val){
return hashCode(Double.doubleToLongBits(val));
}
/**
* Returns a hash code for the specified long value.
*/
public static int hashCode(long val){
return (int)(val ^ (val >>> 32));
}
/**
* Returns the name of the package of the specified class.
*/
public static String getPackageName(Class c){
return getPackageName(c.getName());
}
/**
* Returns the name of the package of the class with the specified (full) name.
*/
public static String getPackageName(String className){
int lastDotIndex = className.lastIndexOf(".");
return lastDotIndex == -1 ? "" : className.substring(0, lastDotIndex);
}
/**
* Returns the short name (excluding the package name) of the specified class.
*/
public static String getClassName(Class c){
return getClassName(c.getName());
}
/**
* Returns the short name (excluding the package name) of the class with the
* specified fully qualified name.
*/
public static String getClassName(String className){
int lastDotIndex = className.lastIndexOf(".");
return lastDotIndex == -1 ? className : className.substring(lastDotIndex + 1);
}
}
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