How To Find Needed Info From Java API Documentation
May 13, 2015
Let's say I'd like to print out something as a prompt without end with a new line char, so the standard System.out.println() is not an option and I'd like to find something else inplace of println().
Where to find that? I googled about that and learned printf() is the one I want, but how to get it from java api documentation.
I have a HTML page with an applet inside it.I have the applet class and all other needed classes in a jar file in jre/lib/ext folder (I'm on windows). But when I open the HTML file in a browser it gives me ClassNotFound exception..The HTML file is this:
I have this HostOnDemand class in its package in a jar file in jre/lib/ext but it can't be found.Since the applet is way too old, I'm using jre1.4.2 and netscape.
why interfaces are needed in Java,Now you saw what a class must do to avail itself of the s... - justpaste.it (if I paste the quote here, I get the "Page not found" error after posting -.^)
the first fragment reads that the compiler must be sure that a method exits at a compile time, whereas the second fragment denies it - if a[i] doesn't have the specified compareTo method, a JVM simply throws an exception.
method called []getLetterGrades but the only hint My professor told me was that I needed to declare another array list for this method and he wouldnt tell me anything else so bummer. But I don't understand why if what we are returning is a char. It would make sense to return an array list of char to get letter grade. Which is what i did but since the function is a char, the array list character wont work as a return.Primarily i would like to know the type that is needed. I just want an explanation for an array list in this method and how it would serve in this method.
Should we always use getters/setters, e.g. even in something like
Java Code:
class Foo { private static int foo; public int getFoo() { return foo; } public void setFoo(int fig) { foo = fig; } } mh_sh_highlight_all('java');
Or should we use the only when there is a good reason to use them, e.g. validation for a setter or may be computing a value to return from some variables etc. ?
I have a .jar that is installed in other computer(outside netbeans). Everything works fine except with report. I am sure the libraries needed for iReport is added in my lib folder but I receive this error message when I to load the report using the program.I use command prompt to see the error:
Java Code:
java -jar projCosting.jar mh_sh_highlight_all('java'); And here is the error message: Java Code: net.sf.jasperreports.engine.JRException: Error compiling report java source files : [b]D:CostingRptCosting_1288072391310_955208.java[/b] at net.sf.jasperreports.engine.design.JRJavacCompiler.compileClasses
[code]....
I have included the library in lib folder but do you think I have to install the iReport application?
The keys in a HashMap and the values in a Set must all be unique, but this can be circumvented when using custom objects in a HashMap and Set, because the compiler has no way to determine if the objects are equal or not, as shown in the example below:
Java Code:
import java.util.LinkedHashMap; import java.util.Map; public class HashCodeEquals { public void run(){ Person p1 = new Person(1, "John"); Person p2 = new Person(2, "Matt"); Person p3 = new Person(1, "John");
[code]....
Obviously the equals method is needed because that compares the two objects. But why is the hashCode method needed?
I have a simple classes here one is interface and another one is abstract class when i try to compile them abstract class is givving compilation error.
public interface MyInterface{ public void getName(); public void getName(String s); } public class HelloWorld{} abstract class SampleClass{
I have to meet certain requirements for this one program, and one of them is as follow: The program will require the user to enter the needed values one after another. If any of the entered values is invalid, then the program will detect that and go into a loop requiring the user to enter a valid value. The program must keep track of the total number of invalid values that the user has entered.
I know how to set a restriction and create a loop to keep asking the same question until it is satisfactory ( in this case I used a while loop) but I am at loss on how I should keep track of the total number of invalid values. I know I can use an increment but how do I set a variable for when the program meets an wrong input from the user.
I am reading from a database(SQL Server 2012) and storing that information in a ResultSet. I am then trying to display that information using a DataTable.
Here is my managed bean
/* * To change this license header, choose License Headers in Project Properties. * To change this template file, choose Tools | Templates * and open the template in the editor. */ package clientspage; import java.io.Serializable;
[Code].....
The ID and the commandLinks are being displayed but the Client is not.
I want to ask that, when a server listen to A port and it accepts a request from a client then the server accepts the request using accept method,but how does the server get the info about the client like wat is the port no and ip address of the client,I read a answer regarding this that Server never gets the port no of client only the ip address and it connects to client using a connection stream but as far I know from networking, a device must have the ip address and port no of the device it wants to connect to.
Suppose there're two classes: Exam and MainExam (contains a main method). class Exam has a constructor public Exam(String firstName, String lastName, int ID). Class MainExam reads data from a textfile. For example, the data can be: John Douglas 57. How can one pass data to the constructor from a textfile?
I was trying to make a UDP voice chat but i couldn't make the receive method work! so i just move on to work with TCP. I found a simple code that i found it pretty easy to understand,but i couldn't make it work, always stuck within exception.
Here is the output I got:
Available mixers:
Java Sound Audio Engine
Microsoft Sound Mapper
WinOS,waveOut,multi threaded
java.lang.IllegalArgumentException: Line unsupported: interface TargetDataLine supporting format PCM_SIGNED, 8000.0 Hz, 16 bit, mono, little-endian, audio data
I am trying to invoke some methods in a for loop in order to print some info stored in a List. But for some reason, compiler pops a message saying "cannot find symbol - method getEmpID(). You are using a symbol here (a name for a variable, method or class) that has not been declared in any visible scope." But I am pretty sure that method getEmpID (as also getName(), getAfm(), and payment() ) have been declared as public.
Note: My List contains objects of different type (SalariedEmployee, HourlyEmployee). I hope this is not the factor causing this problem.
Java Code:
import java.util.*; abstract class Employee{ private String name = ""; private String afm = ""; private long EmpID; static long count=0;
I've got a nasty nullpointer that I have tried to resolve to no avail as of yet. The program should prompt for a listings.txt file and take its info and write to a report file. Here's the stacktrace:
run:
Input file: listings Exception in thread "main" java.lang.NullPointerException at java.io.Writer.<init>(Writer.java:88) at java.io.PrintWriter.<init>(PrintWriter.java:113) at java.io.PrintWriter.<init>(PrintWriter.java:100) at kettask2b.PropertyListingsReport.main(PropertyListingsReport.java:34) Java Result: 1
Some adjustments that I have attempted are:
BufferedWriter pwfo = null; for (int i = 0; i < args.length; i++) { String string = args[i]; pwfo = null;
I am trying to get this to where I can type in a name and it will search through each object and print back the corresponding object info.
Java Code:
import java.util.Scanner; public class MyPeople { public static void main(String[] args) { Person[] p = new Person[] { new Person("Chris", 26, "Male", "NJ", "Single"), new Person("JoAnna", 23, "Female", "NJ", "Single"), new Person("Dana", 24, "Female", "NJ", "Single"), new Person("Dan", 25, "Male", "NJ", "Single"), new Person("Mike", 31, "Male", "NJ", "Married") };
Basically the class is supposed to have a static variable that keeps track of the number of companies (numberOfCompanies) that have been created and a static method that returns the value of this variable. I need to have a constructor and a method to addEmployee, a method to printCompany, and a toString method. The addEmployee method will check that there is only 1 salesperson, 2 designers, and 4 manufacturing persons at a time and will check that there are no more than 7 employees of the company.
The addEmployee method will return a String indicating what the error is (i.e. "There is already a sales person in this company") or a null if the employee was added. If attempting to name a third company, an error message will be shown. what i have so far but my print company mmethod returns null company class :in which i am obliged to use inputdialog because it says that it cannot return void when i use the showmeassage diaolog.
company class:
import java.util.ArrayList; import javax.swing.JOptionPane; public class Company { private ArrayList<Employees> list ; private static int numberOfCompanies;
[Code] ....
error message when print button is clicked:
Exception in thread "AWT-EventQueue-0" java.lang.RuntimeException: JOptionPane: parentComponent does not have a valid parent at javax.swing.JOptionPane.createInternalFrame(Unknown Source) at javax.swing.JOptionPane.showInternalOptionDialog(Unknown Source) at javax.swing.JOptionPane.showInternalMessageDialog(Unknown Source)