Public static final Comparator String CASE_INSENSITIVE_ORDER
in this declaration..
public static final Comparator<String> CASE_INSENSITIVE_ORDER
what does <String> mean?
thanks!
what does the Comparator do. Look at the API and you would see the following description about the compare method.
public int compare(Object o1,
Object o2)Compares its two arguments for order. Returns a negative integer, zero, or a positive integer as the first argument is less than, equal to, or greater than the second.
The implementor must ensure that sgn(compare(x, y)) == -sgn(compare(y, x)) for all x and y. (This implies that compare(x, y) must throw an exception if and only if compare(y, x) throws an exception.)
The implementor must also ensure that the relation is transitive: ((compare(x, y)>0) && (compare(y, z)>0)) implies compare(x, z)>0.
Finally, the implementer must ensure that compare(x, y)==0 implies that sgn(compare(x, z))==sgn(compare(y, z)) for all z.
It is generally the case, but not strictly required that (compare(x, y)==0) == (x.equals(y)). Generally speaking, any comparator that violates this condition should clearly indicate this fact. The recommended language is "Note: this comparator imposes orderings that are inconsistent with equals."
Now your question is about what <String> is in your declaration. It is the type of the objects which are going to be compared.
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Constant values (public static final String) are not shown??
This has already been posted and no body answered. Any help is appreciated.
In web service is it possible to expose the Constants used in the application. Let say for my web service I need to pass value for Operation, possible values for this are (add, delete, update). Is it possible expose these constant values(add, delete, update) visible to client application accesssing the web service.
Server Side:
public static final String ADD = "ADDOPP";
public static final String DELETE = "DELETEOPP";
public static final String UPDATE = "UPDATEOPP";
client Side: mywebserviceport.setOperation( mywebservicePort.ADD );
thanks
vijaySure, you can use JAX-WS and enums.
For example on the server:
@WebService
public class echo {
public enum Status {RED, YELLOW, GREEN}
@WebMethod
public Status echoStatus(Status status) {
return status;
on the client you get.
@WebService(name = "Echo", wsdlLocation ="..." )
public interface Echo {
@WebMethod
public Status echoStatus(
@WebParam(name = "arg0", targetNamespace = "")
Status arg0);
@XmlEnum
public enum Status {
GREEN,
RED,
YELLOW;
public String value() {
return name();
public static Status fromValue(String v) {
return valueOf(v);
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How to call java with public static void main(String[] args) throws by jsp?
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import java.net.MalformedURLException;
import java.io.IOException;
import com.openwave.wappush.*;
public class spServiceInd
private final static String ppgAddress = "http://devgate2.openwave.com:9002/pap";
private final static String[] clientAddress = {"1089478279-49372_devgate2.openwave.com/[email protected]"};
// private final static String[] clientAddress = {"+639209063665/[email protected]"};
private final static String SvcIndURI = "http://devgate2.openwave.com/cgi-bin/mailbox.cgi";
private static void printResults(PushResponse pushResponse) throws WapPushException, MalformedURLException, IOException
System.out.println("hello cze, I'm inside printResult");
//Read the response to find out if the Push Submission succeded.
//1001 = "Accepted for processing"
if (pushResponse.getResultCode() == 1001)
try
String pushID = pushResponse.getPushID();
SimplePush sp = new SimplePush(new java.net.URL(ppgAddress), "SampleApp", "/sampleapp");
StatusQueryResponse queryResponse = sp.queryStatus(pushID, null);
StatusQueryResult queryResult = queryResponse.getResult(0);
System.out.println("Message status: " + queryResult.getMessageState());
catch (WapPushException exception)
System.out.println("*** ERROR - WapPushException (" + exception.getMessage() + ")");
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System.out.println("hello cze, I'm inside SubmitMsg");
try
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SimplePush sp = new SimplePush(new java.net.URL(ppgAddress), "SampleApp", "/sampleapp");
//Send the Service Indication.
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//Print the response from the PPG.
printResults(response);
}//try
catch (WapPushException exception)
System.out.println("*** ERROR - WapPushException (" + exception.getMessage() + ")");
catch (IOException exception)
System.out.println("*** ERROR - IOException (" + exception.getMessage() + ")");
}//SubmitMsg()
public static void main(String[] args) throws WapPushException, IOException
System.out.println("hello cze, I'm inside main");
spServiceInd spsi = new spServiceInd();
spsi.SubmitMsg();
}//main
}//class spServiceIndIn general, classes with main method should be called from command prompt (that's the reason for main method). Remove the main method, put the class in a package and import the apckage in your jsp (java classes should not be in the location as jsps).
When you import the package in jsp, then you can instantiate the class and use any of it's methods or call the statis methods directly:
<%
spServiceInd spsi = new spServiceInd();
spsi.SubmitMsg();
%> -
Declaring public static final variables in jsp?
The question is in the title...
I know this is not a jsp forum, but some people here might know if it's possible or not.
If yes, how to declare them and how to access them from other jsp pages?
ThxIf you need that, you definitely do too much work in your JSPs. You should do all your work in Servlets (or Actions if you're using Struts or something similar).
Your JSPs should only do the presentation.
Remember that JSPs are not classes (they are compiled into classes internally, but you don't have direct access to those).
If you absolutely need such a public static final field that you want to access from several JSPs, just define it in a Class and reference that class from your JSPs. -
Trying to acces the value of a public static final int using reflection
-Java 6
-Windows XP
-Signed Applet
doing the following:
Class.forName(classname).getField(code).getInt(null);
is giving me the error:
java.lang.IllegalAccessException: Class com.cc.applet.util.ServiceConfiguration can not access a member of class com.cc.util.error.codes.SendMessageErrorCodes with modifiers "public static final"
at sun.reflect.Reflection.ensureMemberAccess(Unknown Source)
at java.lang.reflect.Field.doSecurityCheck(Unknown Source)
at java.lang.reflect.Field.getFieldAccessor(Unknown Source)
at java.lang.reflect.Field.getInt(Unknown Source)
I'm not understanding why it can't access the value of the field. Any help would be great.
Edited by: zparticle on Oct 17, 2007 11:07 PMstefan.schulz wrote:
oebert, you are right. Good one.
I actually think that, in this case, the message is misleading. The current implementation of sun.reflect.Reflection.ensureMemberAccess() treats any failing access check the same. It should and could inculde better contextual information.Stefan,
That is a good point. Did you file a RFE with Sun yet? I also think they should provide a more contextual error message in this case.
Gili -
Why can't created an object in the "public static void main(String args[])"
Example:
public Class Exp {
public static void main(String args[])
new Exp2();-------------> To Occur Error
Class Exp2 {
public Exp2()You can't create an inner class within main, because
it is a static method. Inner classes can only be
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!! help using: public static Boolean valueOf(String s)
I am trying to use this simple function to convert a string value to a boolean. According to the documentation for this Boolean method (public static Boolean valueOf(String s)), this should work:
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As a test, I tried to run this line of code:
tmp_bool = Boolean.valueOf("True");
I get this compilation error:
test_file.java:10: incompatible types
found : java.lang.Boolean
required: boolean
tmp_bool = Boolean.valueOf("True");
.....................................^
According to the documentation for SDK 1.4, there is a new function:
public static Boolean valueOf(boolean b)
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Am I somehow using the method wrong?
Thanks!OK, I think I understand now. Thanks.
Let me make sure i have this right...
So basically, if you use variable types of Boolean and need to pass them to methods that take booleans, would you have to call the booleanValue method first?
ex:
Boolean bool_obj;
//example method that takes a boolean
//test_method(boolean b);
test_method ( bool_obj.booleanValue() );
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I'm having a block here... I want to have a constant List, but I can't figure out how to do it so it actually contains the values I want. It's going to be a list of strings about 40 elements long. Obviously, if I didn't need the final, I'd just do List.add( ), but I need to do it right in the constructor. Thanks for the help.
I guess the problem could be reworded, If I wantedto
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how would I initialize the List?You use a static intializer.Ah. I didn't get that out of the question. Thanks for the help.
But here's an example:public class Foo {
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list.add("three");
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Public static boolean contains(string s, string t)
i am just a beginner to java....plz help me out...this is my first time programming.
Is it possibly also your first time posting a question on a technical forum?
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Any body know hat this following code means?
public static final String JAVA_HOME = System.getProperty("java.home");
public static final String CURRENT_DIR = System.getProperty("user.dir");
thanks youIt defines two object variables (JAVA_HOME and CURRENT_DIR), that are:
static - there's only ever one of them, no matter how many times the class they are in is instantiated.
final - cannot be changed.
public - available to all other classes outside of the current class.
The two variables are then assigned to system properties, for a list of system properties and their meanings look here:
http://java.sun.com/docs/books/tutorial/essential/system/properties.html
A 'static final' variable is called a 'constant'. It is very useful when you want to define a variable and keep it that way. For example, if you wrote a program that worked out the area of a circle, you might want a static final variable PI = 3.14159.
Constant variables are usually defined in uppercase. This is not forced, but it's good practice. -
How can i pass the values to method public static void showBoard(boolean[][
I need x and y to pass to the method
public static void showBoard(boolean[][] board
i am very confused as to why its boolean,i know its an array but does that mean values ar true or false only?Thanks
import java.util.Random;
import java.util.Scanner;
public class Life1
public static void main(String[] args)
int x=0;
int y=0;
Scanner keyIn = new Scanner(System.in);
System.out.println("Enter the first dimension of the board : ");
x = keyIn.nextInt();
System.out.println("Enter the second dimension of the board : );
y = keyIn.nextInt();
boolean[][] board = new boolean[x][y];
fillBoard(board);
showBoard(board);
//Ask the user how many generations to show.
board = newBoard(board);
showBoard(board);
//This method randomly populates rows 5-9 of the board
//Rewrite this method to allow the user to populate the board by entering the
//coordinates of the live cells. If the user requests that cell 1, 1 be alive,
//your program should make cell 0,0 alive.
public static void fillBoard(boolean[][] board)
int row, col, isAlive;
Random picker = new Random();
for(row = 4; row < 9; row++)
for(col = 4; col < 9; col++)
if (picker.nextInt(2) == 0)
board[row][col] = false;
else
board[row][col] = true;
//This method displays the board
public static void showBoard(boolean[][] board)
int row, col;
System.out.println();
for(row=0; row < x; row++)
for(col=0; col<y; col++)
if (board[row][col])
System.out.print("X");
else
System.out.print(".");
System.out.println();
System.out.println();
//This method creates the next generation and returns the new population
public static boolean[][] newBoard(boolean[][] board)
int row;
int col;
int neighbors;
boolean[][] newBoard = new boolean[board.length][board[0].length];
makeDead(newBoard);
for(row = 1; row < board.length-1; row++)
for(col = 1; col < board[row].length-1; col++)
neighbors = countNeighbors(row, col, board);
//make this work with one less if
if (neighbors < 2)
newBoard[row][col]=false;
else if (neighbors > 3)
newBoard[row][col] = false;
else if (neighbors == 2)
newBoard[row][col]= board[row][col];
else
newBoard[row][col] = true;
return newBoard;
//This method counts the number of neighbors surrounding a cell.
//It is given the current cell coordinates and the board
public static int countNeighbors(int thisRow, int thisCol, boolean[][] board)
int count = 0;
int row, col;
for (row = thisRow - 1; row < thisRow + 2; row++)
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if (board[row][col])
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if (board[thisRow][thisCol])
count--;
return count;
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public static void makeDead(boolean[][] board)
int row, col;
for(row = 0; row < board.length; row++)
for(col = 0; col < board[row].length; col++)
board[row][col] = false;
}this is what im workin with mabey you can point me in the right directionimport java.util.Random;
/* This class creates an application to simulate John Conway's Life game.
* Output is sent to the System.out object.
* The rules for the Life game are as follows...
* Your final version of the program should explain the game and its use
* to the user.
public class Life
public static void main(String[] args)
//Allow the user to specify the board size
boolean[][] board = new boolean[10][10];
fillBoard(board);
showBoard(board);
//Ask the user how many generations to show.
board = newBoard(board);
showBoard(board);
//This method randomly populates rows 5-9 of the board
//Rewrite this method to allow the user to populate the board by entering the
//coordinates of the live cells. If the user requests that cell 1, 1 be alive,
//your program should make cell 0,0 alive.
public static void fillBoard(boolean[][] board)
int row, col, isAlive;
Random picker = new Random();
for(row = 4; row < 9; row++)
for(col = 4; col < 9; col++)
if (picker.nextInt(2) == 0)
board[row][col] = false;
else
board[row][col] = true;
//This method displays the board
public static void showBoard(boolean[][] board)
int row, col;
System.out.println();
for(row=0; row < 10; row++)
for(col=0; col<10; col++)
if (board[row][col])
System.out.print("X");
else
System.out.print(".");
System.out.println();
System.out.println();
//This method creates the next generation and returns the new population
public static boolean[][] newBoard(boolean[][] board)
int row;
int col;
int neighbors;
boolean[][] newBoard = new boolean[board.length][board[0].length];
makeDead(newBoard);
for(row = 1; row < board.length-1; row++)
for(col = 1; col < board[row].length-1; col++)
neighbors = countNeighbors(row, col, board);
//make this work with one less if
if (neighbors < 2)
newBoard[row][col]=false;
else if (neighbors > 3)
newBoard[row][col] = false;
else if (neighbors == 2)
newBoard[row][col]= board[row][col];
else
newBoard[row][col] = true;
return newBoard;
//This method counts the number of neighbors surrounding a cell.
//It is given the current cell coordinates and the board
public static int countNeighbors(int thisRow, int thisCol, boolean[][] board)
int count = 0;
int row, col;
for (row = thisRow - 1; row < thisRow + 2; row++)
for(col = thisCol - 1; col < thisCol + 2; col++)
if (board[row][col])
count++;
if (board[thisRow][thisCol])
count--;
return count;
//This method makes each cell in a board "dead."
public static void makeDead(boolean[][] board)
int row, col;
for(row = 0; row < board.length; row++)
for(col = 0; col < board[row].length; col++)
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} -
Instantiation of static final objects
Is there a problem with coding the following?:
class A {
public static final A static_final_a_obj = new A ( B.static_final_b_obj );
private B b;
public A ( B b ) {
this.b = b;
class B {
public static final B static_final_b_obj = new B ( A.static_final_a_obj );
private A a;
public B ( A a ) {
this.a = a;
I put log messages in each of the constructors to see if it would cause an infinite loop, but it doesn't seem to. The question is 'why'.. :) How can either of the static final objects ever be fully instantiated?Exactly. It is not executed infinitely.
class A {
public static final A static_final_a_obj = new A ( B.static_final_b_obj );
private B b;
public A ( B b ) {
System.out.println(" A Cons");
this.b = b;
public static void main(String args[]) {
System.out.println("A");
Output:
B Cons
A Cons
A
class B {
public static final B static_final_b_obj = new B ( A.static_final_a_obj );
private A a;
public B ( A a ) {
System.out.println(" B Cons");
this.a = a;
public static void main(String args[]) {
System.out.println("B");
Output:
A Cons
B Cons
B
Edited by: prajeshps on Sep 18, 2007 1:51 PM -
Using equals() to compare strings
It was told in a previous post that when comparing two strings to use the equals()
So rather than doing something like this
package relationships;
public class Starter {
public static void main(String[] args){
String foo = "foo";
String bar = "bar";
if(foo == bar){
System.out.println("Strings are logically equal");
} else if(foo != bar){
System.out.println("Strings are not logically equal");
}Where the console would output "Strings are not logically equal" How would I do this using the equals() (other then using else)
package relationships;
public class Starter {
public static void main(String[] args){
String foo = "foo";
String bar = "bar";
if(foo.equals(bar)){
System.out.println("Strings are logically equal");
} else if( /* WHAT GOES HERE? */ ){
System.out.println("Strings are not logically equal");
}I know to test if they are equal just to go like this foo.equals(bar) but what would I put in the else if?
else if( /* WHAT GOES HERE? */ )Where the console would output "Strings are not
logically equal" How would I do this using the
equals() (other then using else)You don;t need anything else. If it is not true it is false there isn't a third boolean value of maybe or perhaps. -
ERROR: serializable class HelloComponent does not declare a static final
Hi everyone! I'm sorry but I'm a newbie to Java and I'm having some, I assume, basic problems learning to compile and run with javac. Here is my code:
import javax.swing.* ;
import java.awt.* ;
public class MyJava {
* @param args
public static void main(String[] args)
// TODO Auto-generated method stub
JFrame frame = new JFrame( "HelloJava" ) ;
HelloComponent hello = new HelloComponent() ;
frame.add( hello ) ;
frame.setSize( 300, 300 ) ;
frame.setVisible( true ) ;
class HelloComponent extends JComponent
public void paintComponent( Graphics g )
g.drawString( "Hello Java it's me!", 125, 95 ) ;
And here is the error:
1. WARNING in HelloJava.java
(at line 20)
class HelloComponent extends JComponent {
^^^^^^^^^^^^^^
The serializable class HelloComponent does not declare a static final serialVersionUID field of type long
ANY HELP WOULD BE GREAT! THANKS! =)Every time I extend GameLoop, it gives me the warning
serializable class X does not declare a static final serialVersionUID field of type long
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Comparing Strings with "If" statements : help please. :-)
I have an assignment for class... and having lots of trouble trying to figure out what I did wrong. I cannot find a solution.. if anyone can help me with this, it'd be much appreciated.
Assignment Write a program to allow the user to calculate the area and perimeter of a square, or the area and circumference of a circle, or the area of a triangle.
To do this, the user will enter one of the following characters: S, C, or T. The program should then ask the user for the appropriate information in order to make the calculation, and should display the results of the calculation. See the example program execution shown in class.
The program should use dialog boxes.
When expecting an S, C, or T, the program should reject other characters with an appropriate message.
Get extra points for allowing both the uppercase and lowercase versions of a valid character to work. Name the program ShapesCalc.java.My error codes are
incomparable types: java.lang.String and Char
cannot find symbol variable output
incomparable types: java.lang.String and Char
incomparable types: java.lang.String and CharI've asked a friend and they said something about Strings cannot be compared in "If" statements... if that is the case.. how is this supposed to be arranged? If you can point me in the right direction, I will be very grateful! :-)
What I have created so far
import javax.swing.JOptionPane;
public class ShapesCalc {
public static void main(String[] args) {
//Enter S,C, or T
String input = JOptionPane.showInputDialog("Enter S,C, or T");
//If Statements
//Square
if (input == 'S'){
String lengthu = JOptionPane.showInputDialog("Enter length of a square");
double length = Double.parseDouble(lengthu);
double area = length * length;
double perimeter = length * 4;
String ouput = "The area is " + area + " and the perimeter is " + perimeter;
JOptionPane.showMessageDialog(null, output);}
//Circle
else if (input == 'C'){
String radiusu = JOptionPane.showInputDialog("Enter the radius of a circle");
double radius = Double.parseDouble(radiusu);
double area = 3.14159 * radius * radius;
double circumference = 2 * 3.14159 * radius;
String output = "The area is " + area + " and the circumference is " + circumference;
JOptionPane.showMessageDialog(null, output);}
//Triangle
else if (input == 'T'){
String baseu = JOptionPane.showInputDialog("Enter the base of a triangle");
double base = Double.parseDouble(baseu);
String heightu = JOptionPane.showInputDialog("Enter the height of a triangle");
double height = Double.parseDouble(heightu);
String output = "The area is " + (base * height) / 2;
JOptionPane.showMessageDialog(null,output);}
//Error Message
else {
String error = "Incorrect variable please enter S,C, or T only.";
JOptionPane.showMessageDialog(null,error);}
//Signature
String signature = "Rodriguez, Markos has compiled a Java program.";
JOptionPane.showMessageDialog(null,signature);
}Edited by: ZambonieDrivor on Feb 22, 2009 6:52 PMZambonieDrivor wrote:
How would I go about on the extration of a single char from a String to make it comparable, I don't quite understand this part.Read the [Java API|http://java.sun.com/javase/6/docs/api/] for the String class and see what methods it has.
I will convert the == to equals() method.If you want to compare primitives (ints, chars etc) then using == is fine. Only when comparing objects do you use the equals method.
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