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I keep receiving an error massage that I am missing my main method. How do I correct it, any help.
package display;
}
class MathOP{
double num1;
double num2;
double mathadd(){
return num1 + num2;
}
double mathsub(){
return num1 -num2;
}
void setVal(double x, double y) {
num1 = x;
num2 = y;
}
}
class MathOP2 extends MathOP {
double mathadd(){
return num1 + num2;
}
double mathsub(){
return num1 -num2;
}
double mathmul(){
return num1 * num2;
}
double mathdiv(){
return num1 / num2;
}
class display extends MathOP2 {
display() {
System.out.println("MathAdd");
System.out.println("MathSub");
System.out.println("MathMul");
System.out.println("MathDiv");
}
}
}
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Remove "}" after package.
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The packages having class without a Main function are more like a library package. Are you sure you don't want to have a Main function?
You can create a seperate class (maybe inside the same package) and then add the Main function inside it
package packagename;
public class MainClass {
public static void Main(String[] args) {
System.out.println("Hello world!");
}
}
This would be executed as the first function, and you can set it to the default entry point. Which IDE are you using? NetBeans or eclipse?
Main function is the entry point; set by you in properties, and it the very first function to be executed by the application. That is why it is required.
The sh*t I complain about
It's like there ain't a cloud in the sky and it's raining out - Eminem
~! Firewall !~
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I am using jgrasp. Thanks for responding to my post
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This is your third question on this subject, and reinforces my view that you really should follow the link I gave you to the Java Tutorials, and work through them carefully. You are posting a lot of code which does not really fit together in any useful way, so the chances of you stumbling across a working solution are not very high. Posting questions like this is not a good way to learn programming.
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Can someone see where I am getting it wrong, I could not get this code to compile.
class MathOP{
double num1;
double num2;
//create a method mathadd
double mathadd(){
return num1 + num2;
}
// create a method mathsub
double mathsub(){
return num1 -num2;
}
//set value of mathop for test
void setVal(double x, double y) {
num1 = x;
num2 = y;
}
}
// Here MathOP is extended to include multiply and division
class MathOP2 extends MathOP {
double mathadd(){
return num1 + num2;
}
double mathsub(){
return num1 -num2;
}
double mathmul(){
return num1 * num2;
}
double mathdiv(){
return num1 / num2;
}
/************************
Name:
Program
Date:
Purpose:
**************************/
class MathOP{
public static void main(String args[]) {
double num1, num2;
//the try exception is put her to monitor the block of code
try{
double num1 = 0;
double num2 = 5.5/num1;
System.out.println("Division by zero " is + num2");
// Catch exception is to catch the exception from above
}catch (ArithmeticException e){
System.out.println(("Division by zero ") is; + e");
}
System.out.println("After catch statement.");
}
}
boolean Y = true;
System.out.println("Do you want to exist (Y/N)?");
}finally{
if (Y) {
System.out.println("Thanks for using our system");
}else{
System.out.println("run the program again");
}
}
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Please do not repost the same question.
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Please can someone assist in debug the below code. I am trying to add multiply and division method to the code whereby both methods can accepts two parameters and return a value.
class MathOP{
double num1;
double num2;
//create a method mathadd
double mathadd(){
return num1 + num2;
}
// create a method mathsub
double mathsub(){
return num1 -num2;
}
//set value of mathop for test
void setVal(double x, double y) {
num1 = x;
num2 = y;
}
}
/************************
This is a flower box
Name:
Program name:
Date:
Purpose:
**************************/
class TestMathOP {
public static void main (String args[]) {
MathOP mytest1 = new MathOP();
MathOP mytest2 = new MathOP();
MathOP mytest3 = new MathOP();
double Mathadd;
double Mathsub;
double Mathadd1;
//intitialize each text
mytest1.setVal(5.5, 7.5);
mytest2.setVal(5.5, 7.5);
mytest3.setVal(5.5, 7.5);
//get values
Mathadd = mytest1.mathadd();
System.out.println("The sum of two number is " + Mathadd);
//get values of subtraction
Mathsub = mytest2.mathsub();
System.out.println("The subtraction of two number is " + Mathsub);
boolean Y = true;
System.out.println("Do you want to exist (Y/N)?");
if (Y) {
System.out.println("Thanks for using our system");
}else{
System.out.println("run the program again");
}
}
//Modify the code to prompt for the operation
class TestMathOP1 {
void main (String args[]) {
MathOP mytest3 = new MathOP();
double Mathadd1;
Mathadd1 = mytest3.mathadd();
System.out.println("Enter operator + " + Mathadd1);
System.out.println("Do you want another operation (Y/N)?");
}
}
}
modified 23-Feb-15 20:40pm.
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what u want, i didn't understand bro, your code is running well except run the program again.. call
if u have problem then specify correctly
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I can seem to get the other part of the class to run. I mean after the "run the program again".
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double mathadd(){
return num1 + num2;
}
Your methods should accept local parameters rather than having some other method set them in advance, as shown below:
double mathadd(double num1, double num2) {
return num1 + num2;
}
The same with the subtraction method. You then call it with a stament like:
double result = mytest1.mathadd(5.5, 7.12);
The setval method is redundant and should not be used. You also need to import the MathOP class into your test application, rather than trying to define them in your source.
Take a look at http://docs.oracle.com/javase/tutorial/java/index.html[^] for a more detailed explanation of how to write Java.
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Thanks for responding to my post but I am still have issue compiling the code. Can you see what I am doing wrong in the below code?
package display;
class MathOP{
double num1;
double num2;
double mathadd(){
return num1 + num2;
}
double mathsub(){
return num1 -num2;
}
class MathOP2 extends MathOP {
double mathmul(){
return num1 * num2;
}
double mathdiv(){
return num1 / num2;
}
MathOP2 objMath = new MathOP2();
double return = objMath.mathadd(5.5,5.12);
System.out.println("MathAdd" + Mathadd);
double return = objMath;mathsub(42.0,20.2);
System.out.println("MathSub" + Mathsub);
double return = objMath;mathdiv(60.3,20.2);
System.out.println("MathMul" + Mathmul);
double return = objMath;mathmult(10.4,5.4);
System.out.println("MathDiv" + Mathdiv);
}
}
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Your methods in MathOP and MathOP2 are not using method parameters. They should be of the form:
double mathadd(double num1, double num2){
return num1 + num2;
}
As I suggested in my previous message, you should go and work through the Java tutorials.
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//solv by akshgods 
/*
i deleted many thing which is not required in your program,
so always try to make simple and easy dear.
sorry for late reply
*/
package javaapplication8;
import java.util.*;
class MathOP{
//create a method mathadd
double mathadd(double a,double b){
return a+b;
}
// create a method mathsub
double mathsub(double x,double z){
return x-z;
}
}
//TestMathOp class
class TestMathOP {
public static void main (String args[])
{
MathOP mytest1 = new MathOP();
MathOP mytest2 = new MathOP();
double add;
double sub;
/*
scanner class for taking integer input
*/
Scanner sc=new Scanner(System.in);
int f=0;
while(f==0)//while for reapitation of program
{
add = mytest1.mathadd(5.5,7.5);
System.out.println("The sum of two number is " +add);
//get values of subtraction
sub = mytest2.mathsub(5.5,7.5);
System.out.println("The subtraction of two number is " +sub);
System.out.println("Do you want to exist (Y=1/N=0)?");
f=sc.nextInt();//here we are taking value from keybord 1 or 0 for exit or reapeat programm
if (f==1)
{
System.out.println("Thanks for using our system");
break;
}
else
{
System.out.println("run the program again");
}
}
}
}
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Please format your code properly when posting answers.
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what to format ? an how? give example with my post
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Like this
double mathsub(double x,double z){
return x-z;
}
surrounding your code with <pre> tags, by using the code button on the edit window.
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Today I was testing the ArrayList of the Java because I've just started learning the Java after C#. Concept that underlies is the generic, similar to the C#, API is somewhat similar.
But there was a problem, that I faced, I started with the String class objects in the ArrayList and I found surprising that the list allows all type of objects in it. For example the following code from my HelloWorld application.
List list = new ArrayList<String>();
list.add(new JavaHelloCollections());
list.add("String data");
list.add(4345345345.9898996756);
for(Object o : list) {
System.out.println(o);
}
Well, firstly it compiles all fair and doesn't only compile it also prints the result; a little doubty result for the float (or double) type data.
javahellocollections.JavaHelloCollections@529e0c79
String data
4.3453453459899E9
I am using NetBeans and I am really confused of how can this happen. Does JVM perform some .toString() checks there or what? Where actually does this type check or type conversion happens?
The sh*t I complain about
It's like there ain't a cloud in the sky and it's raining out - Eminem
~! Firewall !~
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What you have actually created is a simple List that will accept any type. Try
ArrayList<String> list = new ArrayList<String>();
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+1 Thanks Richard.
The sh*t I complain about
It's like there ain't a cloud in the sky and it's raining out - Eminem
~! Firewall !~
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Afzaal Ahmad Zeeshan wrote: Where actually does this type check or type conversion happens?
Although the previous comment pointed out your code problem it didn't answer this question.
The answer is that this occurs in the compiler and only in the compiler. Quite possible and easy to inject something wrong into it if one is not careful or one just wants to circumvent it.
One will often run into this with situations like the following.
void method(List<String> list) { ... }
void method(List<Integer> list) { ... }
Although these look like two different overloads after the compiler gets done with them the signature will resolve to exactly the same overload (the compiler will throw an error about that.)
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Yeah that makes sense. Thanks for your clarification. Now it does make sense for why did I get problems. But, isn't the List generic? Why would it throw error for attaching a type to the List?
Secondly, I am still just learning and not building any application so "careless" won't apply, I was trying to make the application throw error but it accepted it that cause me to ask the question here. I will continue trying more such "careless" attempts in order to learn more.
The sh*t I complain about
It's like there ain't a cloud in the sky and it's raining out - Eminem
~! Firewall !~
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Afzaal Ahmad Zeeshan wrote: Why would it throw error for attaching a type to the List?
Not sure what you mean by "throw error" but the compiler validates types for generics and will produce a compiler error when it finds those.
Other than that it is possible to put the wrong type in a list because the compiled version doesn't have a type. An error will occur later because as the compiler produces code it puts in checks which impact what happens when you get something out of the list. And one of those checks will fail. Seeing such a error isn't a good thing since it can be very confusing.
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need a simple java code for transport ticketing
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