Direct JDBC Connection to the database.
java.sql.Statement stmt = null;
ResultSet rs = null;
PreparedStatement ps = null;
List result = null;
try {
Class.forName("oracle.jdbc.OracleDriver");
String url = "jdbc:oracle:thin:@mfn2asff4:10005:APPRDEV";
java.sql.Connection conn = DriverManager.getConnection(url,
"sgrtdbo", "sgrt123dbo");
stmt = conn.createStatement();
// TODO Auto-generated method stub
String maxDateInfo="select (max(To_Date(dateinfo,'DD MON YYYY HH24:MI:SS'))) as maxdate from srgt_metrics";
ResultSet resultSet=stmt.executeQuery(maxDateInfo);
while(resultSet.next()){
String maxDateFromDB=resultSet.getString(1);
System.out.println("Max date retrieved from the database is :"+maxDateFromDB);
}
}catch(Exception e){
System.out.println("IN Excepiton e");
e.printStackTrace();
}
Friday, February 23, 2007
Date Formattin in Java.
Things to remember for Simple Date FOrmatting
Letter Date or Time Component Presentation Examples
G Era designator Text AD
y Year Year 1996; 96
M Month in year Month July; Jul; 07
w Week in year Number 27
W Week in month Number 2
D Day in year Number 189
d Day in month Number 10
F Day of week in month Number 2
E Day in week Text Tuesday; Tue
a Am/pm marker Text PM
H Hour in day (0-23) Number 0
k Hour in day (1-24) Number 24
K Hour in am/pm (0-11) Number 0
h Hour in am/pm (1-12) Number 12
m Minute in hour Number 30
s Second in minute Number 55
S Millisecond Number 978
z Time zone General time zone Pacific Standard Time; PST; GMT-08:00
Z Time zone RFC 822 time zone -0800
For Addtional Processing use the following:
Date and Time Pattern Result
"yyyy.MM.dd G 'at' HH:mm:ss z" 2001.07.04 AD at 12:08:56 PDT
"EEE, MMM d, ''yy" Wed, Jul 4, '01
"h:mm a" 12:08 PM
"hh 'o''clock' a, zzzz" 12 o'clock PM, Pacific Daylight Time
"K:mm a, z" 0:08 PM, PDT
"yyyyy.MMMMM.dd GGG hh:mm aaa" 02001.July.04 AD 12:08 PM
"EEE, d MMM yyyy HH:mm:ss Z" Wed, 4 Jul 2001 12:08:56 -0700
"yyMMddHHmmssZ" 010704120856-0700
Sample Code for conversion:
String datefromTable="2/22/2007 6:46:15 PM";
SimpleDateFormat sdf = new SimpleDateFormat("MM/dd/yyyy KK:mm:ss aaa");
SimpleDateFormat sdf2= new SimpleDateFormat("dd MMM yyyy hh:mm:ss");
String fromFile="23 Feb 2007 12:21:12";
java.util.Date d=null;
java.util.Date d2=null;
try{
d=sdf.parse(datefromTable);
d2=sdf2.parse(fromFile);
}catch(Exception e){
e.printStackTrace();
}
System.out.println("Compare Dates : "+d.compareTo(d2));
Letter Date or Time Component Presentation Examples
G Era designator Text AD
y Year Year 1996; 96
M Month in year Month July; Jul; 07
w Week in year Number 27
W Week in month Number 2
D Day in year Number 189
d Day in month Number 10
F Day of week in month Number 2
E Day in week Text Tuesday; Tue
a Am/pm marker Text PM
H Hour in day (0-23) Number 0
k Hour in day (1-24) Number 24
K Hour in am/pm (0-11) Number 0
h Hour in am/pm (1-12) Number 12
m Minute in hour Number 30
s Second in minute Number 55
S Millisecond Number 978
z Time zone General time zone Pacific Standard Time; PST; GMT-08:00
Z Time zone RFC 822 time zone -0800
For Addtional Processing use the following:
Date and Time Pattern Result
"yyyy.MM.dd G 'at' HH:mm:ss z" 2001.07.04 AD at 12:08:56 PDT
"EEE, MMM d, ''yy" Wed, Jul 4, '01
"h:mm a" 12:08 PM
"hh 'o''clock' a, zzzz" 12 o'clock PM, Pacific Daylight Time
"K:mm a, z" 0:08 PM, PDT
"yyyyy.MMMMM.dd GGG hh:mm aaa" 02001.July.04 AD 12:08 PM
"EEE, d MMM yyyy HH:mm:ss Z" Wed, 4 Jul 2001 12:08:56 -0700
"yyMMddHHmmssZ" 010704120856-0700
Sample Code for conversion:
String datefromTable="2/22/2007 6:46:15 PM";
SimpleDateFormat sdf = new SimpleDateFormat("MM/dd/yyyy KK:mm:ss aaa");
SimpleDateFormat sdf2= new SimpleDateFormat("dd MMM yyyy hh:mm:ss");
String fromFile="23 Feb 2007 12:21:12";
java.util.Date d=null;
java.util.Date d2=null;
try{
d=sdf.parse(datefromTable);
d2=sdf2.parse(fromFile);
}catch(Exception e){
e.printStackTrace();
}
System.out.println("Compare Dates : "+d.compareTo(d2));
Converting Strings to Dates in Java
grrrr.. it took me a long time to realize there is a way of doing it. :)
Here is how u make dates from Strings in java.
String datefromTable="23 Feb 2007 13:23:43";
SimpleDateFormat sdf = new SimpleDateFormat("dd MMM yyyy hh:mm:ss");
String fromFile="22 Feb 2007 13:23:43";
java.util.Date d=null;
java.util.Date d2=null;
try{
d=sdf.parse(datefromTable);
d2=sdf.parse(fromFile);
}catch(Exception e){
e.printStackTrace();
}
System.out.println("Compare Dates : "+d.compareTo(d2));
System.out.println("Date value is :"+d);
Major advantage of doing this is you can you java's built in compare to method to compare dates and process accordingly hehe.. lazy to write my own comare to method for strings :)
Here is how u make dates from Strings in java.
String datefromTable="23 Feb 2007 13:23:43";
SimpleDateFormat sdf = new SimpleDateFormat("dd MMM yyyy hh:mm:ss");
String fromFile="22 Feb 2007 13:23:43";
java.util.Date d=null;
java.util.Date d2=null;
try{
d=sdf.parse(datefromTable);
d2=sdf.parse(fromFile);
}catch(Exception e){
e.printStackTrace();
}
System.out.println("Compare Dates : "+d.compareTo(d2));
System.out.println("Date value is :"+d);
Major advantage of doing this is you can you java's built in compare to method to compare dates and process accordingly hehe.. lazy to write my own comare to method for strings :)
Thursday, February 15, 2007
Deployment descriptor "web.xml" is malformed.
U see this error because the order of elements in ur web.xml is different from the dtd its using
ex: UR web.xml shud comply with http://java.sun.com/dtd/web-app_2_3.dtd so if any of the ordering is different you will see the above error.
com.jpmchase.srgt.interceptor.SrgtSessionListener
org.apache.struts.action.ActionServlet
Thursday, February 8, 2007
invoking a url with query parameters
here is how you invoke a url with query parameters
http://localhost:7001/srgt/actions/proposalDetails.do?action=displayView&operURL=yes&proposalId=1230
all the variables set here are your form variables. So in this case proposalDetaislForms shud contain these vars defined
action
operURL
proposalId etc
http://localhost:7001/srgt/actions/proposalDetails.do?action=displayView&operURL=yes&proposalId=1230
all the variables set here are your form variables. So in this case proposalDetaislForms shud contain these vars defined
action
operURL
proposalId etc
Wednesday, January 31, 2007
Iterating through a Hash Map
Lets say you have a hash map
Map currencyMap=new HashMap();
currencyMap=someMapYouGot();
//YOu can iterate thru this map using either the entry set or key set
//here is how
Iterator iterator=currencyMap.keySet().Iterator;
while(iterator.hasNext()){
Object key=iterator.next();
System.out.printn("Key is :"+key.toString());
Object value=currencyMap.get(key);
System.out.println("Value is :"+value.toString());
}
//Other way of doing is:
Iterator iterator=currencyMap.entrySet().iterator;
while(iterator.hasNext()){
Map.Entry entry=(Entry)iterator.next();
Object key=entry.getKey();
Object value=entry.getValue();
}
}
//Yet another way of doing is create a collection of values from the map and iterate thru the list:)
//Here is how
List list=new ArrayList();
Collection coll=currencyMap.values();
list.addAll(coll);
--Happy Coding
}
Map currencyMap=new HashMap();
currencyMap=someMapYouGot();
//YOu can iterate thru this map using either the entry set or key set
//here is how
Iterator iterator=currencyMap.keySet().Iterator;
while(iterator.hasNext()){
Object key=iterator.next();
System.out.printn("Key is :"+key.toString());
Object value=currencyMap.get(key);
System.out.println("Value is :"+value.toString());
}
//Other way of doing is:
Iterator iterator=currencyMap.entrySet().iterator;
while(iterator.hasNext()){
Map.Entry entry=(Entry)iterator.next();
Object key=entry.getKey();
Object value=entry.getValue();
}
}
//Yet another way of doing is create a collection of values from the map and iterate thru the list:)
//Here is how
List list=new ArrayList();
Collection coll=currencyMap.values();
list.addAll(coll);
--Happy Coding
}
Thursday, January 11, 2007
import java.lang.reflect.Method;
import java.util.Comparator;
import java.util.Date;
import java.util.Map;
public class ObjectComparator implements Comparator
{
/** Constant to specify a descending sort for the attribute */
public static final int SORT_DESCENDING = 0;
/** Constant to specify an ascending sort for the attribute */
public static final int SORT_ASCENDING = 1;
/** The fully-qualified class name of the object to be sorted */
private String sortObjectClassName;
/** The actual Class object of the object to be sorted */
private Class sortObjectClass;
/** An array of Method objects that correspond to each sort attribute */
private Method sortFieldGetterMethods[];
/** An array of Strings that represent the argument(s) to pass to the getter method (really only necessary for Map objects) */
private String sortFieldMethodArgs[];
/** An integer array that corresponds to each sort attribute's sort order */
private int sortFieldOrder[];
/** If the classes to sort are instances of map, this is set to true */
private boolean isMap;
/**
* Private Constructor - not used
* @exception ObjectComparatorException
**/
private ObjectComparator() throws ObjectComparatorException
{
}
/**
* Constructor for ObjectComparator when passing in the actual object that will be sorted
* by later on. This is an alternative to passing in the fully-qualified class name for the
* objects that will be sorted.
*
* @param sortObject An instance of the object that will be sorted on
* @param sortFields An array of all the field names to sort by
* @param sortFieldOrder An integer array representing the sort order for the fields that will be sorted.
* Should either contain ObjectComparator.SORT_DESCENDING or ObjectComparator.SORT_ASCENDING
*
* @exception ObjectComparatorException if any errors occurred during creation
**/
public ObjectComparator(
Object sortObject,
String[] sortFields,
int[] sortFieldOrder)
throws ObjectComparatorException
{
this.sortObjectClass = sortObject.getClass();
this.sortObjectClassName = sortObjectClass.getName();
this.checkIsMap();
loadMethods(sortFields, sortFieldOrder);
}
/**
* Constructor for ObjectComparator when passing in the fully-qualified class name of the objects that will be sorted
* by later on. This is an alternative to passing in an instance of the actual object.
*
* @param sortObjectClassName The fully-qualified class name for the objects that will be sorted
* @param sortFields An array of all the field names to sort by
* @param sortFieldOrder An integer array representing the sort order for the fields that will be sorted.
* Should either contain ObjectComparator.SORT_DESCENDING or ObjectComparator.SORT_ASCENDING
*
* @exception ObjectComparatorException if any errors occurred during creation
**/
public ObjectComparator(
String sortObjectClassName,
String[] sortFields,
int[] sortFieldOrder)
throws ObjectComparatorException
{
try
{
this.sortObjectClass = Class.forName(sortObjectClassName);
this.sortObjectClassName = sortObjectClassName;
this.checkIsMap();
}
catch (ClassNotFoundException e)
{
throw new ObjectComparatorException(
"Error creating ObjectComparator: " + e);
}
loadMethods(sortFields, sortFieldOrder);
}
/**
* Constructor for ObjectComparator when passing in the actual object that will be sorted
* by later on. This is an alternative to passing in the fully-qualified class name for the
* objects that will be sorted. This constructor is also used when you want to sort by a maximum
* of only 3 fields, as opposed to passing in an array of fields to sort by.
*
* @param sortObject An instance of the object that will be sorted on
* @param sortField1 First field to sort by
* @param sortField1SortOrder Sort order for first field, either ObjectComparator.SORT_DESCENDING or ObjectComparator.SORT_ASCENDING
* @param sortField2 Second field to sort by
* @param sortField2SortOrder Sort order for second field, either ObjectComparator.SORT_DESCENDING or ObjectComparator.SORT_ASCENDING
* @param sortField3 Third field to sort by
* @param sortField3SortOrder Sort order for third field, either ObjectComparator.SORT_DESCENDING or ObjectComparator.SORT_ASCENDING
*
* @exception ObjectComparatorException if any errors occurred during creation
**/
public ObjectComparator(
Object sortObject,
String sortField1,
int sortField1SortOrder,
String sortField2,
int sortField2SortOrder,
String sortField3,
int sortField3SortOrder)
throws ObjectComparatorException
{
this.sortObjectClass = sortObject.getClass();
this.sortObjectClassName = sortObjectClass.getName();
this.checkIsMap();
loadMethods(
sortField1,
sortField1SortOrder,
sortField2,
sortField2SortOrder,
sortField3,
sortField3SortOrder);
}
/**
* Constructor for ObjectComparator when passing in the fully-qualified class name of the objects that will be sorted
* by later on. This is an alternative to passing in an instance of the actual object.
* This constructor is also used when you want to sort by a maximum
* of only 3 fields, as opposed to passing in an array of fields to sort by.
*
* @param sortObjectClassName An instance of the object that will be sorted on
* @param sortField1 First field to sort by
* @param sortField1SortOrder Sort order for first field, either ObjectComparator.SORT_DESCENDING or ObjectComparator.SORT_ASCENDING
* @param sortField2 Second field to sort by
* @param sortField2SortOrder Sort order for second field, either ObjectComparator.SORT_DESCENDING or ObjectComparator.SORT_ASCENDING
* @param sortField3 Third field to sort by
* @param sortField3SortOrder Sort order for third field, either ObjectComparator.SORT_DESCENDING or ObjectComparator.SORT_ASCENDING
*
* @exception ObjectComparatorException if any errors occurred during creation
**/
public ObjectComparator(
String sortObjectClassName,
String sortField1,
int sortField1SortOrder,
String sortField2,
int sortField2SortOrder,
String sortField3,
int sortField3SortOrder)
throws ObjectComparatorException
{
try
{
this.sortObjectClass = Class.forName(sortObjectClassName);
this.sortObjectClassName = sortObjectClassName;
}
catch (ClassNotFoundException e)
{
throw new ObjectComparatorException(
"Error creating ObjectComparator: " + e);
}
loadMethods(
sortField1,
sortField1SortOrder,
sortField2,
sortField2SortOrder,
sortField3,
sortField3SortOrder);
}
/**
* Loads the proper getter method for the field
*
* @param sortFields An array of all the field names to sort by
* @param sortFieldOrder An integer array representing the sort order for the fields that will be sorted.
* Should either contain ObjectComparator.SORT_DESCENDING or ObjectComparator.SORT_ASCENDING
*
* @exception ObjectComparatorException if any errors occurred during creation
**/
private void loadMethods(String[] sortFields, int[] sortFieldOrder)
throws ObjectComparatorException
{
if (sortFields.length != sortFieldOrder.length)
{
throw new ObjectComparatorException(
"Error creating ObjectComparator. Sort Fields array count "
+ "doesn't match Sort Field Order array count.");
}
//Determine the appropriate Method object for the field to be sorted by
String sortField = "";
int sortOrder = 0;
int length = sortFields.length;
this.sortFieldGetterMethods = new Method[length];
this.sortFieldOrder = new int[length];
this.sortFieldMethodArgs = new String[length];
int getterCount = 0;
for (int i = 0; i < length; i++)
{
sortField = sortFields[i];
sortOrder = sortFieldOrder[i];
if ((sortField != null && sortField != ""))
{
this.sortFieldGetterMethods[getterCount] =
getMethodName(sortField);
if (this.isMap) this.sortFieldMethodArgs[getterCount]=sortField; // Map objects use method "get" and pass the field name as an arg
this.sortFieldOrder[getterCount] = sortOrder;
getterCount++;
}
}
}
/**
* Loads the proper getter method for the field
*
* @param sortField1 First field to sort by
* @param sortField1SortOrder Sort order for first field, either ObjectComparator.SORT_DESCENDING or ObjectComparator.SORT_ASCENDING
* @param sortField2 Second field to sort by
* @param sortField2SortOrder Sort order for second field, either ObjectComparator.SORT_DESCENDING or ObjectComparator.SORT_ASCENDING
* @param sortField3 Third field to sort by
* @param sortField3SortOrder Sort order for third field, either ObjectComparator.SORT_DESCENDING or ObjectComparator.SORT_ASCENDING
*
* @exception ObjectComparatorException if any errors occurred during creation
**/
private void loadMethods(
String sortField1,
int sortField1SortOrder,
String sortField2,
int sortField2SortOrder,
String sortField3,
int sortField3SortOrder)
throws ObjectComparatorException
{
this.sortFieldGetterMethods = new Method[3];
this.sortFieldOrder = new int[3];
if (sortField1 != null && !sortField1.equals(""))
{
this.sortFieldGetterMethods[0] = getMethodName(sortField1);
if (this.isMap) this.sortFieldMethodArgs[0]=sortField1; // Map objects use method "get" and pass the field name as an arg
this.sortFieldOrder[0] = sortField1SortOrder;
}
if (sortField2 != null && !sortField2.equals(""))
{
this.sortFieldGetterMethods[1] = getMethodName(sortField2);
if (this.isMap) this.sortFieldMethodArgs[1]=sortField2; // Map objects use method "get" and pass the field name as an arg
this.sortFieldOrder[1] = sortField2SortOrder;
}
if (sortField3 != null && !sortField3.equals(""))
{
this.sortFieldGetterMethods[2] = getMethodName(sortField3);
if (this.isMap) this.sortFieldMethodArgs[2]=sortField3; // Map objects use method "get" and pass the field name as an arg
this.sortFieldOrder[2] = sortField3SortOrder;
}
}
/**
* Checks if the Class object currently set and associated with this ObjectComparator
* implements interface Map
*
*/
private void checkIsMap() {
/*
if (this.sortObjectClass.isInstance( aMapObject ) ) {
this.isMap = true;
}
*/
/*
* The method Class.isInstance(Object) above doesn't seem to work. Even when I created
* an explicit instance of the object to sort (like a 'Hashtable'), it never
* detected the correct object type. Instead, I am trying to get a hard instance
* of the object so I can check instanceof, which *does* seem to work. If I can't
* create an instance of the object using the empty constructor, then I'm assuming
* it's not a Map!
*/
try {
Object o = this.sortObjectClass.newInstance();
if (o instanceof Map) {
this.isMap = true;
}
}
catch (InstantiationException e)
{
// Do nothing, just assume it's not a map
/*
throw new ObjectComparatorException(
"could not check for map '"
+ " (map=" + this.isMap + ") findmap: " + findmap.toString()
+ "'. Error is: "
+ e); */
}
catch (IllegalAccessException e)
{
// Do nothing, just assume it's not a map
}
}
/**
* The implementation of the Comparator interface's compare method
*
* @param obj1 The first object to compare
* @param obj2 The second object to compare
* @return int
* @see java.util.Comparator#compare(Object, Object)
**/
public int compare(Object obj1, Object obj2)
{
int returnVal = 0;
try
{
Object obj1FieldValue = null;
Object obj2FieldValue = null;
int length = sortFieldGetterMethods.length;
Method getterMethod = null;
String[] methodArg = null;
for (int i = 0; i < length; i++)
{
getterMethod = sortFieldGetterMethods[i];
methodArg = new String[] { sortFieldMethodArgs[i] };
if (getterMethod != null)
{
if (this.isMap) {
// If we're a Map, we need to invoke get() method with the key as an argument
obj1FieldValue = getterMethod.invoke(obj1, methodArg);
obj2FieldValue = getterMethod.invoke(obj2, methodArg);
} else {
// If we're not a Map, we need to invoke the getter method
obj1FieldValue = getterMethod.invoke(obj1, null);
obj2FieldValue = getterMethod.invoke(obj2, null);
}
if(obj1FieldValue == null){
if (obj2FieldValue instanceof String )
obj1FieldValue = new String();
else if (obj2FieldValue instanceof Integer )
obj1FieldValue = new Integer(0);
else if (obj2FieldValue instanceof Long)
obj1FieldValue = new Long(0);
else if (obj2FieldValue instanceof Float)
obj1FieldValue = new Float(0);
else if (obj2FieldValue instanceof Double)
obj1FieldValue = new Double(0);
else if (obj2FieldValue instanceof Date)
obj1FieldValue = new Date(0);
else obj1FieldValue = new Object();
}
if (obj1FieldValue instanceof String )
{
if ( obj2FieldValue == null )
{
obj2FieldValue = new String();
}
returnVal =
obj1FieldValue.toString().toUpperCase().compareTo(
obj2FieldValue.toString().toUpperCase());
}
else if (obj1FieldValue instanceof Integer)
{
if ( obj2FieldValue == null )
{
obj2FieldValue = new Integer(0);
}
Integer obj1Integer = (Integer) obj1FieldValue;
Integer obj2Integer = (Integer) obj2FieldValue;
returnVal = obj1Integer.compareTo(obj2Integer);
}
else if (obj1FieldValue instanceof Long)
{
if ( obj2FieldValue == null )
{
obj2FieldValue = new Long(0);
}
Long obj1Long = (Long) obj1FieldValue;
Long obj2Long = (Long) obj2FieldValue;
returnVal = obj1Long.compareTo(obj2Long);
}
else if (obj1FieldValue instanceof Float)
{
if ( obj2FieldValue == null )
{
obj2FieldValue = new Float(0);
}
Float obj1Float = (Float) obj1FieldValue;
Float obj2Float = (Float) obj2FieldValue;
returnVal = obj1Float.compareTo(obj2Float);
}
else if (obj1FieldValue instanceof Double)
{
if ( obj2FieldValue == null )
{
obj2FieldValue = new Double(0);
}
Double obj1Double = (Double) obj1FieldValue;
Double obj2Double = (Double) obj2FieldValue;
returnVal = obj1Double.compareTo(obj2Double);
}
else if (obj1FieldValue instanceof Date)
{
if ( obj2FieldValue == null )
{
obj2FieldValue = new Date(0);
}
Date obj1Date = (Date) obj1FieldValue;
Date obj2Date = (Date) obj2FieldValue;
returnVal = obj1Date.compareTo(obj2Date);
}
else
{
if ( obj2FieldValue == null )
{
obj2FieldValue = new Object();
}
returnVal =
obj1FieldValue.toString().compareTo(
obj2FieldValue.toString());
}
if (returnVal != 0)
{
if (sortFieldOrder[i] == SORT_DESCENDING)
{
returnVal = returnVal * -1;
}
break;
}
}
}
}
catch (Exception e)
{
//Can't throw an exception since the inherited compare method doesn't define it
// That means any exception when comparing the objects goes into a black hole, and
// you won't be able to know why your compare didn't work.
returnVal = 0;
}
return returnVal;
}
/**
* Used to retrieve the 'getter' method, as a Method object, for the passed in field name
*
* @param fieldName The field name
* @return The getter method
* @throws ObjectComparatorException
**/
private Method getMethodName(String fieldName)
throws ObjectComparatorException
{
Method theMethod = null;
String methodName = null;
Class[] parameterTypes = null;
String firstChar = "";
if (fieldName != null && !fieldName.equals(""))
{
if (this.isMap) {
// If we're a Map, we'll always check for method "get()"
methodName="get";
// Object o = new Object();
Object o = new Object();
parameterTypes = new Class[] { o.getClass() };
} else {
// If we're not a Map, check for bean-style get method (i.e. "getMyProperty()")
firstChar = fieldName.substring(0, 1);
if (fieldName.length() >= 2)
{
methodName =
"get" + firstChar.toUpperCase() + fieldName.substring(1);
}
else
{
methodName = "get" + firstChar.toUpperCase();
}
}
}
try
{
theMethod = sortObjectClass.getMethod(methodName, parameterTypes);
}
catch (NoSuchMethodException e)
{
throw new ObjectComparatorException(
"No getter method matches the field name passed in '"
+ fieldName + " (map=" + this.isMap + ") "
+ "'. Error is: "
+ e);
}
return theMethod;
}
}
import java.util.Comparator;
import java.util.Date;
import java.util.Map;
public class ObjectComparator implements Comparator
{
/** Constant to specify a descending sort for the attribute */
public static final int SORT_DESCENDING = 0;
/** Constant to specify an ascending sort for the attribute */
public static final int SORT_ASCENDING = 1;
/** The fully-qualified class name of the object to be sorted */
private String sortObjectClassName;
/** The actual Class object of the object to be sorted */
private Class sortObjectClass;
/** An array of Method objects that correspond to each sort attribute */
private Method sortFieldGetterMethods[];
/** An array of Strings that represent the argument(s) to pass to the getter method (really only necessary for Map objects) */
private String sortFieldMethodArgs[];
/** An integer array that corresponds to each sort attribute's sort order */
private int sortFieldOrder[];
/** If the classes to sort are instances of map, this is set to true */
private boolean isMap;
/**
* Private Constructor - not used
* @exception ObjectComparatorException
**/
private ObjectComparator() throws ObjectComparatorException
{
}
/**
* Constructor for ObjectComparator when passing in the actual object that will be sorted
* by later on. This is an alternative to passing in the fully-qualified class name for the
* objects that will be sorted.
*
* @param sortObject An instance of the object that will be sorted on
* @param sortFields An array of all the field names to sort by
* @param sortFieldOrder An integer array representing the sort order for the fields that will be sorted.
* Should either contain ObjectComparator.SORT_DESCENDING or ObjectComparator.SORT_ASCENDING
*
* @exception ObjectComparatorException if any errors occurred during creation
**/
public ObjectComparator(
Object sortObject,
String[] sortFields,
int[] sortFieldOrder)
throws ObjectComparatorException
{
this.sortObjectClass = sortObject.getClass();
this.sortObjectClassName = sortObjectClass.getName();
this.checkIsMap();
loadMethods(sortFields, sortFieldOrder);
}
/**
* Constructor for ObjectComparator when passing in the fully-qualified class name of the objects that will be sorted
* by later on. This is an alternative to passing in an instance of the actual object.
*
* @param sortObjectClassName The fully-qualified class name for the objects that will be sorted
* @param sortFields An array of all the field names to sort by
* @param sortFieldOrder An integer array representing the sort order for the fields that will be sorted.
* Should either contain ObjectComparator.SORT_DESCENDING or ObjectComparator.SORT_ASCENDING
*
* @exception ObjectComparatorException if any errors occurred during creation
**/
public ObjectComparator(
String sortObjectClassName,
String[] sortFields,
int[] sortFieldOrder)
throws ObjectComparatorException
{
try
{
this.sortObjectClass = Class.forName(sortObjectClassName);
this.sortObjectClassName = sortObjectClassName;
this.checkIsMap();
}
catch (ClassNotFoundException e)
{
throw new ObjectComparatorException(
"Error creating ObjectComparator: " + e);
}
loadMethods(sortFields, sortFieldOrder);
}
/**
* Constructor for ObjectComparator when passing in the actual object that will be sorted
* by later on. This is an alternative to passing in the fully-qualified class name for the
* objects that will be sorted. This constructor is also used when you want to sort by a maximum
* of only 3 fields, as opposed to passing in an array of fields to sort by.
*
* @param sortObject An instance of the object that will be sorted on
* @param sortField1 First field to sort by
* @param sortField1SortOrder Sort order for first field, either ObjectComparator.SORT_DESCENDING or ObjectComparator.SORT_ASCENDING
* @param sortField2 Second field to sort by
* @param sortField2SortOrder Sort order for second field, either ObjectComparator.SORT_DESCENDING or ObjectComparator.SORT_ASCENDING
* @param sortField3 Third field to sort by
* @param sortField3SortOrder Sort order for third field, either ObjectComparator.SORT_DESCENDING or ObjectComparator.SORT_ASCENDING
*
* @exception ObjectComparatorException if any errors occurred during creation
**/
public ObjectComparator(
Object sortObject,
String sortField1,
int sortField1SortOrder,
String sortField2,
int sortField2SortOrder,
String sortField3,
int sortField3SortOrder)
throws ObjectComparatorException
{
this.sortObjectClass = sortObject.getClass();
this.sortObjectClassName = sortObjectClass.getName();
this.checkIsMap();
loadMethods(
sortField1,
sortField1SortOrder,
sortField2,
sortField2SortOrder,
sortField3,
sortField3SortOrder);
}
/**
* Constructor for ObjectComparator when passing in the fully-qualified class name of the objects that will be sorted
* by later on. This is an alternative to passing in an instance of the actual object.
* This constructor is also used when you want to sort by a maximum
* of only 3 fields, as opposed to passing in an array of fields to sort by.
*
* @param sortObjectClassName An instance of the object that will be sorted on
* @param sortField1 First field to sort by
* @param sortField1SortOrder Sort order for first field, either ObjectComparator.SORT_DESCENDING or ObjectComparator.SORT_ASCENDING
* @param sortField2 Second field to sort by
* @param sortField2SortOrder Sort order for second field, either ObjectComparator.SORT_DESCENDING or ObjectComparator.SORT_ASCENDING
* @param sortField3 Third field to sort by
* @param sortField3SortOrder Sort order for third field, either ObjectComparator.SORT_DESCENDING or ObjectComparator.SORT_ASCENDING
*
* @exception ObjectComparatorException if any errors occurred during creation
**/
public ObjectComparator(
String sortObjectClassName,
String sortField1,
int sortField1SortOrder,
String sortField2,
int sortField2SortOrder,
String sortField3,
int sortField3SortOrder)
throws ObjectComparatorException
{
try
{
this.sortObjectClass = Class.forName(sortObjectClassName);
this.sortObjectClassName = sortObjectClassName;
}
catch (ClassNotFoundException e)
{
throw new ObjectComparatorException(
"Error creating ObjectComparator: " + e);
}
loadMethods(
sortField1,
sortField1SortOrder,
sortField2,
sortField2SortOrder,
sortField3,
sortField3SortOrder);
}
/**
* Loads the proper getter method for the field
*
* @param sortFields An array of all the field names to sort by
* @param sortFieldOrder An integer array representing the sort order for the fields that will be sorted.
* Should either contain ObjectComparator.SORT_DESCENDING or ObjectComparator.SORT_ASCENDING
*
* @exception ObjectComparatorException if any errors occurred during creation
**/
private void loadMethods(String[] sortFields, int[] sortFieldOrder)
throws ObjectComparatorException
{
if (sortFields.length != sortFieldOrder.length)
{
throw new ObjectComparatorException(
"Error creating ObjectComparator. Sort Fields array count "
+ "doesn't match Sort Field Order array count.");
}
//Determine the appropriate Method object for the field to be sorted by
String sortField = "";
int sortOrder = 0;
int length = sortFields.length;
this.sortFieldGetterMethods = new Method[length];
this.sortFieldOrder = new int[length];
this.sortFieldMethodArgs = new String[length];
int getterCount = 0;
for (int i = 0; i < length; i++)
{
sortField = sortFields[i];
sortOrder = sortFieldOrder[i];
if ((sortField != null && sortField != ""))
{
this.sortFieldGetterMethods[getterCount] =
getMethodName(sortField);
if (this.isMap) this.sortFieldMethodArgs[getterCount]=sortField; // Map objects use method "get" and pass the field name as an arg
this.sortFieldOrder[getterCount] = sortOrder;
getterCount++;
}
}
}
/**
* Loads the proper getter method for the field
*
* @param sortField1 First field to sort by
* @param sortField1SortOrder Sort order for first field, either ObjectComparator.SORT_DESCENDING or ObjectComparator.SORT_ASCENDING
* @param sortField2 Second field to sort by
* @param sortField2SortOrder Sort order for second field, either ObjectComparator.SORT_DESCENDING or ObjectComparator.SORT_ASCENDING
* @param sortField3 Third field to sort by
* @param sortField3SortOrder Sort order for third field, either ObjectComparator.SORT_DESCENDING or ObjectComparator.SORT_ASCENDING
*
* @exception ObjectComparatorException if any errors occurred during creation
**/
private void loadMethods(
String sortField1,
int sortField1SortOrder,
String sortField2,
int sortField2SortOrder,
String sortField3,
int sortField3SortOrder)
throws ObjectComparatorException
{
this.sortFieldGetterMethods = new Method[3];
this.sortFieldOrder = new int[3];
if (sortField1 != null && !sortField1.equals(""))
{
this.sortFieldGetterMethods[0] = getMethodName(sortField1);
if (this.isMap) this.sortFieldMethodArgs[0]=sortField1; // Map objects use method "get" and pass the field name as an arg
this.sortFieldOrder[0] = sortField1SortOrder;
}
if (sortField2 != null && !sortField2.equals(""))
{
this.sortFieldGetterMethods[1] = getMethodName(sortField2);
if (this.isMap) this.sortFieldMethodArgs[1]=sortField2; // Map objects use method "get" and pass the field name as an arg
this.sortFieldOrder[1] = sortField2SortOrder;
}
if (sortField3 != null && !sortField3.equals(""))
{
this.sortFieldGetterMethods[2] = getMethodName(sortField3);
if (this.isMap) this.sortFieldMethodArgs[2]=sortField3; // Map objects use method "get" and pass the field name as an arg
this.sortFieldOrder[2] = sortField3SortOrder;
}
}
/**
* Checks if the Class object currently set and associated with this ObjectComparator
* implements interface Map
*
*/
private void checkIsMap() {
/*
if (this.sortObjectClass.isInstance( aMapObject ) ) {
this.isMap = true;
}
*/
/*
* The method Class.isInstance(Object) above doesn't seem to work. Even when I created
* an explicit instance of the object to sort (like a 'Hashtable'), it never
* detected the correct object type. Instead, I am trying to get a hard instance
* of the object so I can check instanceof, which *does* seem to work. If I can't
* create an instance of the object using the empty constructor, then I'm assuming
* it's not a Map!
*/
try {
Object o = this.sortObjectClass.newInstance();
if (o instanceof Map) {
this.isMap = true;
}
}
catch (InstantiationException e)
{
// Do nothing, just assume it's not a map
/*
throw new ObjectComparatorException(
"could not check for map '"
+ " (map=" + this.isMap + ") findmap: " + findmap.toString()
+ "'. Error is: "
+ e); */
}
catch (IllegalAccessException e)
{
// Do nothing, just assume it's not a map
}
}
/**
* The implementation of the Comparator interface's compare method
*
* @param obj1 The first object to compare
* @param obj2 The second object to compare
* @return int
* @see java.util.Comparator#compare(Object, Object)
**/
public int compare(Object obj1, Object obj2)
{
int returnVal = 0;
try
{
Object obj1FieldValue = null;
Object obj2FieldValue = null;
int length = sortFieldGetterMethods.length;
Method getterMethod = null;
String[] methodArg = null;
for (int i = 0; i < length; i++)
{
getterMethod = sortFieldGetterMethods[i];
methodArg = new String[] { sortFieldMethodArgs[i] };
if (getterMethod != null)
{
if (this.isMap) {
// If we're a Map, we need to invoke get() method with the key as an argument
obj1FieldValue = getterMethod.invoke(obj1, methodArg);
obj2FieldValue = getterMethod.invoke(obj2, methodArg);
} else {
// If we're not a Map, we need to invoke the getter method
obj1FieldValue = getterMethod.invoke(obj1, null);
obj2FieldValue = getterMethod.invoke(obj2, null);
}
if(obj1FieldValue == null){
if (obj2FieldValue instanceof String )
obj1FieldValue = new String();
else if (obj2FieldValue instanceof Integer )
obj1FieldValue = new Integer(0);
else if (obj2FieldValue instanceof Long)
obj1FieldValue = new Long(0);
else if (obj2FieldValue instanceof Float)
obj1FieldValue = new Float(0);
else if (obj2FieldValue instanceof Double)
obj1FieldValue = new Double(0);
else if (obj2FieldValue instanceof Date)
obj1FieldValue = new Date(0);
else obj1FieldValue = new Object();
}
if (obj1FieldValue instanceof String )
{
if ( obj2FieldValue == null )
{
obj2FieldValue = new String();
}
returnVal =
obj1FieldValue.toString().toUpperCase().compareTo(
obj2FieldValue.toString().toUpperCase());
}
else if (obj1FieldValue instanceof Integer)
{
if ( obj2FieldValue == null )
{
obj2FieldValue = new Integer(0);
}
Integer obj1Integer = (Integer) obj1FieldValue;
Integer obj2Integer = (Integer) obj2FieldValue;
returnVal = obj1Integer.compareTo(obj2Integer);
}
else if (obj1FieldValue instanceof Long)
{
if ( obj2FieldValue == null )
{
obj2FieldValue = new Long(0);
}
Long obj1Long = (Long) obj1FieldValue;
Long obj2Long = (Long) obj2FieldValue;
returnVal = obj1Long.compareTo(obj2Long);
}
else if (obj1FieldValue instanceof Float)
{
if ( obj2FieldValue == null )
{
obj2FieldValue = new Float(0);
}
Float obj1Float = (Float) obj1FieldValue;
Float obj2Float = (Float) obj2FieldValue;
returnVal = obj1Float.compareTo(obj2Float);
}
else if (obj1FieldValue instanceof Double)
{
if ( obj2FieldValue == null )
{
obj2FieldValue = new Double(0);
}
Double obj1Double = (Double) obj1FieldValue;
Double obj2Double = (Double) obj2FieldValue;
returnVal = obj1Double.compareTo(obj2Double);
}
else if (obj1FieldValue instanceof Date)
{
if ( obj2FieldValue == null )
{
obj2FieldValue = new Date(0);
}
Date obj1Date = (Date) obj1FieldValue;
Date obj2Date = (Date) obj2FieldValue;
returnVal = obj1Date.compareTo(obj2Date);
}
else
{
if ( obj2FieldValue == null )
{
obj2FieldValue = new Object();
}
returnVal =
obj1FieldValue.toString().compareTo(
obj2FieldValue.toString());
}
if (returnVal != 0)
{
if (sortFieldOrder[i] == SORT_DESCENDING)
{
returnVal = returnVal * -1;
}
break;
}
}
}
}
catch (Exception e)
{
//Can't throw an exception since the inherited compare method doesn't define it
// That means any exception when comparing the objects goes into a black hole, and
// you won't be able to know why your compare didn't work.
returnVal = 0;
}
return returnVal;
}
/**
* Used to retrieve the 'getter' method, as a Method object, for the passed in field name
*
* @param fieldName The field name
* @return The getter method
* @throws ObjectComparatorException
**/
private Method getMethodName(String fieldName)
throws ObjectComparatorException
{
Method theMethod = null;
String methodName = null;
Class[] parameterTypes = null;
String firstChar = "";
if (fieldName != null && !fieldName.equals(""))
{
if (this.isMap) {
// If we're a Map, we'll always check for method "get()"
methodName="get";
// Object o = new Object();
Object o = new Object();
parameterTypes = new Class[] { o.getClass() };
} else {
// If we're not a Map, check for bean-style get method (i.e. "getMyProperty()")
firstChar = fieldName.substring(0, 1);
if (fieldName.length() >= 2)
{
methodName =
"get" + firstChar.toUpperCase() + fieldName.substring(1);
}
else
{
methodName = "get" + firstChar.toUpperCase();
}
}
}
try
{
theMethod = sortObjectClass.getMethod(methodName, parameterTypes);
}
catch (NoSuchMethodException e)
{
throw new ObjectComparatorException(
"No getter method matches the field name passed in '"
+ fieldName + " (map=" + this.isMap + ") "
+ "'. Error is: "
+ e);
}
return theMethod;
}
}
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