I was giving a quick skim to some tutorials on the internet where I have found the exception that is handled is also declared in the throws clause of the method wrapping the try-catch block. For a code representation consider the following:
public void methodName() throws IOException {
try {
...
} catch (IOException ex) {
.... TODO handle exception
}
}
I have studied about the hierarchy of exception classes in which Throwable class comes at the top and two of its direct subclasses are Error and Exception..I just want to ask if in some code snippet we throw an instance of Error or its subclass within the try catch block then will that be also called "exception handling" ? I am asking this because Error class is not a child class of Exception therefore cant be said an Exception, therefore handling the same should not be called exception handling
View Replies View RelatedI have a file greenGrow.txt, and every three lines of the file has a last name, first name, and yard size. Every time a Customer object is created, I need to read the file 3 lines and assign the object a last name, first name, and yard size.
Snippet of my code:
import java.io.*;
import java.util.*;
public class Customer {
private String lastName;
private String firstName;
private int yardSize;
[Code] .....
My issue is that I cannot call readFile() from the constructor, and I'm assuming that's because I throw Exception on readFile(). Is this a simple fix, or am I looking at it the wrong way?
what is the use of checked exception.I know unchecked exception or Runtime exception are thrown by jvm whenever programmer makes any mistake in logic and current thread is terminated.But checked Exception are checked at compile time so that compiler compels programmer to put risky methods in try catch clause. And this checked Exception are caused due to problem in IO operation or any such operation which the programmer can't control.Programmer can't do anything to avoid this checked exception but can catch this exception.
Now the question is Why compiler compels checked exception to be put in try catch clause but doesn't complain anything in case of Runtime Exception???
int nRows = 0;
for (EITest testCurr : testList) {
testCaseListArray[nRows] = new Object[3];
String testName = testCurr.getTestName();
LOG.info("testName=" + testName);
testCaseListArray[nRows][0] = testName;
[Code] ....
This throws null pointer exception because of array initialization error. I tried this:
int nRows=0;
for(EITest testCurr: testList){
testCaseListArray[nRows] = new Object[3];
String testName = testCurr.getTestName();
LOG.info("testName=" + testName);
testCaseListArray[nRows][0] = testName;
[Code] ....
But this is not complete solution.
2) I want to make this as a collection object such as array list instead of Array declaration.
The 2 minute drill from page 69 SCJP kathy and bert book, says regarding Interfaces, that - "A legal nonabstract implementing class must not declare any new checked exceptions for an implementation method."
When I try the below given code in eclipse , it does not throw any errors . (Here I have tried to throw NullPointerException from testFunc whereas the interface function throws IllegalStateExc)
package abstracttesting;
public class StaticCheck implements check{
public void testFunc() throws NullPointerException{
// TODO Auto-generated method stub
} public static void main(String[] args) {
// TODO Auto-generated method stub
}
}
interface check{
void testFunc() throws IllegalStateException;
}
Is there any connection between packages and exception handling in java. Means is it necessary to create a package before trying exception handling examples?
View Replies View RelatedIs there a special mechanism through which exception can be handled in a constructor?
Suppose while creation of an object there occurred an exception while creating an object, and the object is half constructed. How do we make sure we handle this kind of exceptions in a constructor?
For one of my last labs for the semester, my professor is having the class go back to our very first program and apply some of the exception handling that we just recently learned about. Here's my improved code so far:
Java Code: import java.util.*;
import java.lang.*;
public class Lab2Part1 {
public static void main (String [] args) {
Scanner input = new Scanner (System.in);
[code]....
My code compiles fine, but even if I enter an integer or a double, it saves the number as a string, and prints that out as the name. Is there any way to get around this? Or do I need to use something besides a try-catch?
I have been working on a problem dealing with exception handling and text input output for a few days now. The exercise is a two part exercise. The first part of the exercise I have to write a program to display the total salary for assistant professors, associate professors, full professors, and all faculty, respectively, and display the average salary for assistant professors, associate professors, full professors, and all faculty, respectfully using the what is posted on the [URL] .... Each line in the file consists of a faculty member's first name, last name, rank, and salary. The second part of the exercise I have to take my code and change it so that it
-lets the user enter the name of the file to be read,
-Uses a try-catch block to handle the FileNotFoundException displaying instead The file already exists..
... Use a second catch block to ignore any other exception thrown.
... Design your code so that, if the user enters a file that does not exist, the program prompts the user to enter again a file name.
and I need to Note: In order to catch the FileNotFoundException, you need to include import
java.io.FileNotFoundException;
package pkg14.pkg25;
import java.util.Scanner;
import java.io.IOException;
import java.net.MalformedURLException;
import java.net.URL;
[code]...
I want to use my given code as base class
Java Code:
public static void file(String[] arg) throws IOException{
BufferedReader in;
String line;
try{
System.out.println("Reading word");
in =new BufferedReader(new FileReader("inp.txt"));
[Code] .....
I know I can calculate the sum of squares as such:
// SumSquares.java: calculate the sum of two squares
class SumSquares {
static int sumSquares(int a, int B)/>/> {
int asquare;
int bsquare;
[Code] ....
But how can I modify the code so that it inputs a list of integer values in the range of -100 to 100 from the keyboard and computes the sum of the squares input values. And how would I go about using exception handling to ensure that the input values are in range and are legal integers.
The requirement is to write a rectangle class and a test class, which include try-catch blocks and exception handling. Exceptions, involving try, catch, throw, throws, and finally commands,how to write a code about basic things, but in the test class, it gives me specific width and height so that i dont konw how to write a try-catch blocks an exception handling in this test class.There is my two classes, they are separated.
public class Rectangle {
double width ;
double height ;
Rectangle(){
width = 1;
height = 1;
[code]....
I am trying to learn how to use file input/output in addition to exception handling... The problem is my textbook wrote this chapter for a version of Java that hasn't come out yet, so everything I do "according to the textbook" doesn't work. any feedback on correcting these exception errors because I am not sure what is causing them or how to fix them.
I was able to have it display the name of the book in the Book.txt file, but when I added the second part if the file doesn't exist, that's when the errors came up and it wouldn't compile.
import java.io.*;
import java.util.*;
public class DisplayBook
{
public static void main(String[] args) {
try {
File book = new File("Book.txt");
FileInputStream in = new FileInputStream(book);
[Code]...
These are the compilation error messages I am receiving: (I have managed to get it down from 7 errors to just 4, but now I'm stuck)
DisplayBook.java:15: error: unreported exception IOException; must be caught or declared to be thrown
while ((letter = in.read()) != -1) //if file exists, displays book title
^
DisplayBook.java:24: error: unreported exception FileNotFoundException; must be caught or declared to be thrown
[Code] ....
4 errors
class MultipleReturn {
int getInt() {
int returnVal = 10;
try {
String[] students = {"Harry", "Paul"};
//System.out.println(students[5]); //if i remove comment
[Code] .....
I know I can calculate the sum of squares as such:
// SumSquares.java: calculate the sum of two squares
class SumSquares {
static int sumSquares(int a, int B)/>/> {
int asquare;
int bsquare;
[Code] .....
But how can I modify the code so that it inputs a list of integer values in the range of -100 to 100 from the keyboard and computes the sum of the squares input values. And how would I go about using exception handling to ensure that the input values are in range and are legal integers.
I have written the following code to calculate tax payments based on income and filing status :
import java.util.Scanner;
public class computeTax {
public static void main(String[] args) {
Scanner input = new Scanner(System.in);
// prompt for filing status
System.out.println("enter '0' for single filer,");
[Code] ....
The while loop initiated on line 21 is there so that in case the wrong input is given at the prompt given in line 24, the program outputs "please type the right answer" with the command on line 254 before looping back to line 24 and prompting the user to enter his status number. The program works as long as the input at line 28 is an integer. Not surprisingly if the erroneous input here is not an integer, the program outputs the following error message :
Exception in thread "main" java.util.InputMismatchException
at java.util.Scanner.throwFor(Scanner.java:909)
at java.util.Scanner.next(Scanner.java:1530)
at java.util.Scanner.nextInt(Scanner.java:2160)
at java.util.Scanner.nextInt(Scanner.java:2119)
at computeTax.main(computeTax.java:28
To try to solve this I used the Try / Catch technique with the following version of the code :
import java.util.Scanner;
public class computeTax {
public static void main(String[] args) {
Scanner input = new Scanner(System.in);
// prompt for filing status
System.out.println("enter '0' for single filer,");
[Code] ....
Right, so I got this program. It takes input from the user and assigns it to fields on an object. But, it's meant to check the users input. If the user enters bad input, it's supposed to throw this exception. For each of these exceptions, theres a class specifically for it.
public class PayrollDemo
{
public static void main(String[] args)
{
Payroll pr = new Payroll ("Test Name", 234);
System.out.println("Current Employee Information.
");
System.out.println("Name: " + pr.getName());
System.out.println("ID: " + pr.getID());
System.out.println("Hourly Pay Rate: " + pr.getHourlyPayRate());
[Code] ....
And this is the exception class.
public class InvalidNameException extends Exception
{
/**
No-arg constructor
*/
public InvalidNameException()
{
super("Invalid name");
}
}
PayrollDemo.java:43: error: cannot find symbol
InvalidNameException.InvalidNameException();
^
symbol: method InvalidNameException()
location: class InvalidNameException
1 error
It's just meant to tell the user that they entered an invalid value, which would mean if they entered an empty string instead of a name.
can we achieve runtime polymorphism by data members?
View Replies View RelatedI have a program which runs perfectly fine in Eclipse. however, the same program after exporting to jar in desktop and then executing in cmd gives exception.
why is this difference.
in eclipse. it is built up 1.6 JDK and run using 1.6 JRE.
in CMD, it runs by 1.7 JRE.
can this JRE version make a difference. Technically should not i believe.
value1 = text1.getText();
value2 = text2.getText();
Connect c = new Connect(value1,value2);
if(c.check()== true)
{
Menu start = new Menu(c.getID());
dispose();
[code].....
I get an error "unreported exception java.SQLException; must be caught or declared to be thrown" how can i solve this I have taken a few basic classes but never got to exceptions.
I want to encrypt and decrypt a txt file by using PGP.I completed my PGP Encryption.I'm getting an error in PGP Decryption. The error msg as follows
Quote:
Exception in thread "main" java.lang.IllegalArgumentException: Invalid PGP message
at com.newpackage.bouncy.PGPUtils.getDataList(PGPUtil s.java:502)
at com.newpackage.bouncy.PGPUtils.decryptFile(PGPUtil s.java:198)
at com.newpackage.bouncy.PGPFileProcessor.decrypt(PGP FileProcessor.java:56)
at com.newpackage.bouncy.Tester.testDecrypt(Tester.ja va:46)
at com.newpackage.bouncy.Tester.main(Tester.java:61)
I am getting this error in the following line of my code.
PGPObjectFactory factory=new PGPObjectFactory(PGPUtil.getDecoderStream(is));
=>> Object obj=factory.nextObject();//here i am getting obj as null
if (obj == null) {
//System.out.println("Invalid PGP Message");
//System.exit(0);
[Code] .....
So I've been working on this program to make tournament matches for beach volley.
First little info: (I'm Belgian so some words are Dutch)
-Class Speler: has arraylist with information with which player already has been played (codesLijst)
-Class Inschrijvingen: makes players sign up with their level and name
-Class Wedstrijd: makes matches, checks with Inschrijvingen if the players already have played together. If so, gives message that they need to change partner. If not, makes them a team.
Now if I run the program with fresh players, none of them have had a partner, it works fine. If I make just one new team and the other already exists, it also works fine. It's when I make the two teams with existing records (to see whether they already played together), that the error comes.I know there's a lot of code duplicate, will clear out eventually, this is just a raw version.
CLASS SPELER
import java.util.ArrayList;
public class Speler {
private Wedstrijden wedstrijd;
private Inschrijvingen inschrijving;
private String naam, ploeg;
private int setPunten, winPunten;
private long time;
private String code;
private ArrayList<String> lijstCodes = new ArrayList<String>();
[code]....
class Arg
{
public void rt()throws Exception
{
System.out.println("hi");
throw new RuntimeException();
}
public static void main(String args[])
[code]...
the way to handle the exception that has been in the catch block{b.rt()} .
I have the below code :
public class Beyond {
static Float i;
public static void main(String[] args) {
float y = 7 * i;
}
}
It gives : Exception in thread "main" java.lang.NullPointerException : Line 5...Why is it giving NPE? Isnt the variable defaulted with 0.0f? Also, I am not performing any dot operation, it's just a multiplication operation.
Why I have this out of bounds exception? I highlighted the code that the error is in
public String encrypt() {
//TODO: Complete this method
int groupMoves = 0;
int testing = 0;
String encrypted = "";
//a b c d e f g h i j k l
//1 2 0 1 2 0 1 2 0 1 2 0
[Code] ....