ModelUtil.java
/**
*
* Copyright 2003-2007 Jive Software.
*
* Licensed 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.
*/
package org.jivesoftware.smackx.workgroup.util;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import java.util.ListIterator;
/**
* Utility methods frequently used by data classes and design-time
* classes.
*/
public final class ModelUtil {
private ModelUtil() {
// Prevents instantiation.
}
/**
* This is a utility method that compares two objects when one or
* both of the objects might be <CODE>null</CODE> The result of
* this method is determined as follows:
* <OL>
* <LI>If <CODE>o1</CODE> and <CODE>o2</CODE> are the same object
* according to the <CODE>==</CODE> operator, return
* <CODE>true</CODE>.
* <LI>Otherwise, if either <CODE>o1</CODE> or <CODE>o2</CODE> is
* <CODE>null</CODE>, return <CODE>false</CODE>.
* <LI>Otherwise, return <CODE>o1.equals(o2)</CODE>.
* </OL>
* <p/>
* This method produces the exact logically inverted result as the
* {@link #areDifferent(Object, Object)} method.<P>
* <p/>
* For array types, one of the <CODE>equals</CODE> methods in
* {@link java.util.Arrays} should be used instead of this method.
* Note that arrays with more than one dimension will require some
* custom code in order to implement <CODE>equals</CODE> properly.
*/
public static final boolean areEqual(Object o1, Object o2) {
if (o1 == o2) {
return true;
}
else if (o1 == null || o2 == null) {
return false;
}
else {
return o1.equals(o2);
}
}
/**
* This is a utility method that compares two Booleans when one or
* both of the objects might be <CODE>null</CODE> The result of
* this method is determined as follows:
* <OL>
* <LI>If <CODE>b1</CODE> and <CODE>b2</CODE> are both TRUE or
* neither <CODE>b1</CODE> nor <CODE>b2</CODE> is TRUE,
* return <CODE>true</CODE>.
* <LI>Otherwise, return <CODE>false</CODE>.
* </OL>
* <p/>
*/
public static final boolean areBooleansEqual(Boolean b1, Boolean b2) {
// !jwetherb treat NULL the same as Boolean.FALSE
return (b1 == Boolean.TRUE && b2 == Boolean.TRUE) ||
(b1 != Boolean.TRUE && b2 != Boolean.TRUE);
}
/**
* This is a utility method that compares two objects when one or
* both of the objects might be <CODE>null</CODE>. The result
* returned by this method is determined as follows:
* <OL>
* <LI>If <CODE>o1</CODE> and <CODE>o2</CODE> are the same object
* according to the <CODE>==</CODE> operator, return
* <CODE>false</CODE>.
* <LI>Otherwise, if either <CODE>o1</CODE> or <CODE>o2</CODE> is
* <CODE>null</CODE>, return <CODE>true</CODE>.
* <LI>Otherwise, return <CODE>!o1.equals(o2)</CODE>.
* </OL>
* <p/>
* This method produces the exact logically inverted result as the
* {@link #areEqual(Object, Object)} method.<P>
* <p/>
* For array types, one of the <CODE>equals</CODE> methods in
* {@link java.util.Arrays} should be used instead of this method.
* Note that arrays with more than one dimension will require some
* custom code in order to implement <CODE>equals</CODE> properly.
*/
public static final boolean areDifferent(Object o1, Object o2) {
return !areEqual(o1, o2);
}
/**
* This is a utility method that compares two Booleans when one or
* both of the objects might be <CODE>null</CODE> The result of
* this method is determined as follows:
* <OL>
* <LI>If <CODE>b1</CODE> and <CODE>b2</CODE> are both TRUE or
* neither <CODE>b1</CODE> nor <CODE>b2</CODE> is TRUE,
* return <CODE>false</CODE>.
* <LI>Otherwise, return <CODE>true</CODE>.
* </OL>
* <p/>
* This method produces the exact logically inverted result as the
* {@link #areBooleansEqual(Boolean, Boolean)} method.<P>
*/
public static final boolean areBooleansDifferent(Boolean b1, Boolean b2) {
return !areBooleansEqual(b1, b2);
}
/**
* Returns <CODE>true</CODE> if the specified array is not null
* and contains a non-null element. Returns <CODE>false</CODE>
* if the array is null or if all the array elements are null.
*/
public static final boolean hasNonNullElement(Object[] array) {
if (array != null) {
final int n = array.length;
for (int i = 0; i < n; i++) {
if (array[i] != null) {
return true;
}
}
}
return false;
}
/**
* Returns a single string that is the concatenation of all the
* strings in the specified string array. A single space is
* put between each string array element. Null array elements
* are skipped. If the array itself is null, the empty string
* is returned. This method is guaranteed to return a non-null
* value, if no expections are thrown.
*/
public static final String concat(String[] strs) {
return concat(strs, " "); //NOTRANS
}
/**
* Returns a single string that is the concatenation of all the
* strings in the specified string array. The strings are separated
* by the specified delimiter. Null array elements are skipped. If
* the array itself is null, the empty string is returned. This
* method is guaranteed to return a non-null value, if no expections
* are thrown.
*/
public static final String concat(String[] strs, String delim) {
if (strs != null) {
final StringBuilder buf = new StringBuilder();
final int n = strs.length;
for (int i = 0; i < n; i++) {
final String str = strs[i];
if (str != null) {
buf.append(str).append(delim);
}
}
final int length = buf.length();
if (length > 0) {
// Trim trailing space.
buf.setLength(length - 1);
}
return buf.toString();
}
else {
return ""; // NOTRANS
}
}
/**
* Returns <CODE>true</CODE> if the specified {@link String} is not
* <CODE>null</CODE> and has a length greater than zero. This is
* a very frequently occurring check.
*/
public static final boolean hasLength(String s) {
return (s != null && s.length() > 0);
}
/**
* Returns <CODE>null</CODE> if the specified string is empty or
* <CODE>null</CODE>. Otherwise the string itself is returned.
*/
public static final String nullifyIfEmpty(String s) {
return ModelUtil.hasLength(s) ? s : null;
}
/**
* Returns <CODE>null</CODE> if the specified object is null
* or if its <CODE>toString()</CODE> representation is empty.
* Otherwise, the <CODE>toString()</CODE> representation of the
* object itself is returned.
*/
public static final String nullifyingToString(Object o) {
return o != null ? nullifyIfEmpty(o.toString()) : null;
}
/**
* Determines if a string has been changed.
*
* @param oldString is the initial value of the String
* @param newString is the new value of the String
* @return true If both oldString and newString are null or if they are
* both not null and equal to each other. Otherwise returns false.
*/
public static boolean hasStringChanged(String oldString, String newString) {
if (oldString == null && newString == null) {
return false;
}
else if ((oldString == null && newString != null)
|| (oldString != null && newString == null)) {
return true;
}
else {
return !oldString.equals(newString);
}
}
public static String getTimeFromLong(long diff) {
final String HOURS = "h";
final String MINUTES = "min";
final String SECONDS = "sec";
final long MS_IN_A_DAY = 1000 * 60 * 60 * 24;
final long MS_IN_AN_HOUR = 1000 * 60 * 60;
final long MS_IN_A_MINUTE = 1000 * 60;
final long MS_IN_A_SECOND = 1000;
diff = diff % MS_IN_A_DAY;
long numHours = diff / MS_IN_AN_HOUR;
diff = diff % MS_IN_AN_HOUR;
long numMinutes = diff / MS_IN_A_MINUTE;
diff = diff % MS_IN_A_MINUTE;
long numSeconds = diff / MS_IN_A_SECOND;
diff = diff % MS_IN_A_SECOND;
StringBuilder buf = new StringBuilder();
if (numHours > 0) {
buf.append(numHours + " " + HOURS + ", ");
}
if (numMinutes > 0) {
buf.append(numMinutes + " " + MINUTES + ", ");
}
buf.append(numSeconds + " " + SECONDS);
String result = buf.toString();
return result;
}
/**
* Build a List of all elements in an Iterator.
*/
public static <T> List<T> iteratorAsList(Iterator<T> i) {
ArrayList<T> list = new ArrayList<T>(10);
while (i.hasNext()) {
list.add(i.next());
}
return list;
}
/**
* Creates an Iterator that is the reverse of a ListIterator.
*/
public static <T> Iterator<T> reverseListIterator(ListIterator<T> i) {
return new ReverseListIterator<T>(i);
}
}
/**
* An Iterator that is the reverse of a ListIterator.
*/
class ReverseListIterator<T> implements Iterator<T> {
private ListIterator<T> _i;
ReverseListIterator(ListIterator<T> i) {
_i = i;
while (_i.hasNext())
_i.next();
}
public boolean hasNext() {
return _i.hasPrevious();
}
public T next() {
return _i.previous();
}
public void remove() {
_i.remove();
}
}