This question already has answers here:
Eclipse command line arguments
(4 answers)
Closed 3 years ago.
Trying to run a program that swaps names. The task is simple: input > Alice Bob Alex, output > Alex Bob Alice
P.s. Maybe the problem is stupid, but I just recently started programming, so I don't know what to do
I try to run the code in Eclipse - gives an index error. I start in the console - gives an error of the main name. Tried to pass through the internal debugger in Eclipse - writes that I am using obsolete methods. In the end, nothing is clear./
public class Noob {
public static void main(String[] args) {
// TODO Auto-generated method stub
System.out.print(args[2]);
System.out.print(" " + args[1]);
System.out.println(" " + args[0]);
}
}
Error message from Eclipse:
Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: Index 2 out of bounds for length 0
at noob/noob.Noob.main(Noob.java:7)
Console (the file name is Noob.java)
First I compiled src file (> javac Noob.java)
Then I ran it (> java Noob)
Error: Could not find or load main class Noob
Caused by: java.lang.NoClassDefFoundError: noob/Noob (wrong name: Noob)
You need to pass three arguments
This is the steps you need to follow, to passing arguments
1-) Click on Run -> Run Configurations
2-) Click on Arguments tab
3-) In Program Arguments section , Enter your arguments.
4-) Click Apply
You are not passing correctly the values to your program. If you call the program from command line with java myProgram Alice Bob Alex your code should work.
Moreover, you can pass the values to your code through Eclipse directly inside Run Configuration option.
Also, it would be better to not hard code the values. Try this:
for (int i=args.length-1; i>=0; i--) {
System.out.print(args[i] + ' ');
}
System.out.println("");
Related
Summary
1. I am import java.io.console,i am not getting any error in my code,
code is correct, I thought, It's getting some error in eclipse
software... Error :
Exception in thread "main" java.lang.NullPointerException at
loops.Escapey.main(Escapey.java:9)
Coding:
package loops;
import java.io.Console;
public class Escapey {
public static void main(String[] args) {
Console ar = System.console(); // creating a new object for console
String name = ar.readLine("how old are you ?"); //reads a user input
System.out.printf("%s - pretty age",name);
}
}
Ouput :
- I except the output how old are you ?? 18 18 - pretty age
But the actual output is getting error... Exception in thread "main"
java.lang.NullPointerException at loops.Escapey.main(Escapey.java:9)
I assume you are running this into some IDE. Since System.console returns the attached console, if you run it into IDE, it will return NULL. The better approach is to use Scanner class. If you really want to use System.console, you will have to test it on some console. If on Mac, run the terminal. On Linux any of the terminal apps would work.
If we run this in IDE (Intellij), it is throwing null pointer exception. Since this is related to console, I tried to execute this in command line and it works fine.
Execute these steps in terminal or command line and it will work
1) javac Escapey.java
2) java Escapey
This question already has answers here:
Java ArrayIndexOutOfBound
(4 answers)
Closed 4 years ago.
public class Exercise10 {
public static void main(String[] args) {
System.out.println("args[0] = " + args[0]);
System.out.println("args[1] = " + args[1]);
System.out.println("args[2] = " + args[2]);
}
}
The error message I get is: Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 0
The "args" String array argument to main() is populated by the command-line arguments you give to your program when you run it. Since you presumably haven't given it any, looking up the 0th one is quite reasonably an ArrayIndexOutOfBoundsException.
If you are invoking this with java on the command line, try $ java Exercise10 arg0 arg1 arg2
If you are invoking it from an IDE, you'll need to figure out how that IDE supports passing command line arguments. For example, in Eclipse, I believe there should be an Arguments tab in the Run dialog.
"Arg" as said in the names equals to Arguments, You haven't passed any Argument to your program hence it raises the error ArrayIndexOutOfBound, You can pass Arguments to your program by executing it as a jar in command prompt java -jar myJar.jar a b c
I am working my way through "Java: A Beginner's Guide", Sixth Edition and I've encountered an area where I'm typing precisely what the book says, but I'm getting a undesired output.
Here's my class:
// Display all command-line information
public class CLDemo {
public static void main(String args[]) {
System.out.println("There are " + args.length + " command-line arguments");
System.out.println("They are: ");
for(int i = 0; i < args.length; i++)
System.out.println("arg[" + i + "]: " + args[i]);
}
}
My console output:
There are 0 command-line arguments
They are:
Desired console output:
There are 3 command-line arguments
There are:
arg[0]: one
arg[1]: two
arg[2]: three
I'm using Eclipse IDE for Java Developers
Version: Kepler Service Release 1
Build id: 20130919-0819
Any thoughts re: why the number of arguments from my code don't match the book's count of arguments would be greatly appreciated.
Update:
The solution to my issue turned out to be very simple. I had been running the sample projects in Eclipse by pressing the "Run" button without specifying arguments, as I've done for the prior 164 pages of the book without issue. The book instructed me to execute the program from the command line as follows:
java CLDemo one two three // where one two three are the arguments passed
Thank you to those who steered me to the solution.
It seems you are running the program from Eclipse where by default zero arguments got passed.
If you want to pass your arguments, you can do it through run -- >run configuration --> arguments tab.
Guide
This question is unlikely to help any future visitors; it is only relevant to a small geographic area, a specific moment in time, or an extraordinarily narrow situation that is not generally applicable to the worldwide audience of the internet. For help making this question more broadly applicable, visit the help center.
Closed 10 years ago.
I am at a very introductory level of programming with java. I am writing a simple code that involves taking an investment and adding an intrest rate into it. The code is not finished yet but I hav run into the java.lang.ClassNotFoundException error. Since I am so new to java, I have not yet run into this problem before. Where my confusion comes in is the program will compile. I really don't know how to approach this problem.
As I said I dont have a clue about where to start on this, here is the error.
Exception in thread "main" java.lang.NoClassDefFoundError: CDCalc/java
Caused by: java.lang.ClassNotFoundException: CDCalc.java
at java.net.URLClassLoader$1.run(URLClassLoader.java:202)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:190)
at java.lang.ClassLoader.loadClass(ClassLoader.java:306)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301)
at java.lang.ClassLoader.loadClass(ClassLoader.java:247)
The entire code
import java.util.Scanner;
public class CDCalc
{
public static void main(String args[])
{
int Count = 0;
int Investment = 0;
double Rate = 0;
Scanner userInput = new Scanner(System.in);
System.out.println("How much money do you want to invest?");
int Invest = userInput.nextInt();
System.out.println("How many years will your term be?");
double Term = userInput.nextInt();
System.out.println("Investing: " + Investment);
System.out.println(" Term: " + Term);
if (Term <= 1)
{
Rate = .3;
}
else if (Term <= 2)
{
Rate = .45;
}
else if (Term <= 3)
{
Rate = .95;
}
else if (Term <= 4)
{
Rate = 1.5;
}
else if (Term <= 5)
{
Rate = 1.8;
}
System.out.println("Total is: " + (Rate * Invest));
}
}
I would greatly appreciate any help on this. Thanks
edit
I apologize, I should have included this. The code did compile just fine, the problem came in when I ran it. I did use javav CDCalc.java and java CDCalc and thats when the error came up. The even stranger thing is I didn't change a thing, closed out terminal and my text editor, deleted the saved files, reopened everything, saved it, compiled it, and it runs fine now. I apologize again for this post but it seems it fixed itself! –
Your code should compile fine. The way you compile Java files is different than how you execute them.
You compile with
javac CDCalc.java
...and run them with
java CDCalc
Looks like you tried to run it as java CDCalc.java, but it should be just java CDCalc.
The Java command takes a class name (not a file name), so there is no ".java" at the end, and no slashes or backslashes but dots for the package name (your class does not have a package).
This is an sample example:
public class HelloWorldDemo {
public static void main(String args[]) {
System.out.println("Hello world test message");
}
}
This is sample hello world program,When i compile this program using javac HelloWorldDemo.java command, this compiles fine and generates HelloWorldDemo.class in the current directory,
After running this programm using java HelloWorldDemo command, I am getting the below exceptions.
Exception in thread "main" java.lang.NoClassFoundError: HelloWorldDemo
thread main throws this error and exit the program abnormally.
This reason for this error is java virtual machine can not find class file at run time. java command looks for the classes that are there in the current directory, so if your class file is not in current directory, you have to set in classpath, so the solution is to place this .class file in the classpath
classpath is the enviornment variable in every system which points to class files in the directories. if you classfile is in jar file, jar should be in classpath. classpath can be absolute(complete path) or relative path( related to directory )
solve java.lang.NoClassDefFoundError :-
HelloWorldDemo.class is not avialble at runtime, so we have to set the class file to java command using -classpath option
java -classpath . HelloWorld
This is for fixing NoClassDefFoundError error by setting classpath inline for java command.
We are instructing the jvm to look for the HelloWorldDemo.class in the current directory by specifying .
if class file is in different directory, we need specify the complete directory absolute or relative path instead of . for java command
Fix for java.lang.NoClassDefFoundError in windows:-
To solve NoClassDefFoundError error in windows , we have to set CLASSPATH environment variable.
to set classpath in windows, we have to configure the below values
set CLASSPATH=%CLASSPATH%;.;
%CLASSPATH% means existing classpath to be added and . points to current directory
After setting classpath,
java HelloWorldDemo
command works fine and prints hello world message
Your program seems fine. Did you compile your java file using Javac?
You need to perform steps below:
Compiling the .java file (source code) using javac
javac CDCalc.java
This should create a class file named CDCalc.class
Executing the compiled class file using java
java CDCalc
I've just started using eclipse and java and I'm not used to either one of them. I wrote a simple helloworld-programm, but the next task (school) was to create a program that takes a userinput (from commandline) and responds with the highest number of two. The code I wrote looks like following:
public class Larger {
/**
* #param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub
if(args.length < 2)
{
System.out.print("Too few parameters submitted.");
return;
}
int num1 = Integer.parseInt(args[0]);
int num2 = Integer.parseInt(args[1]);
System.out.print(Math.max(num1, num2));
}
}
It all works well when I hit the "run"-button in eclipse, but later when I browse the source-files and tries to run "java Larger.class 2 4" i get an error from java.exe saying that no class was found.
Any idea what this can be?
When it fails, are you invoking the Java process through Eclipse or the command line? It sounds like you're doing it from the command line. In that case, you don't specify the ".class" portion when invoking your Java program. Try :
java Larger 2 4
The "run" button launch your program with the adequate classpath (the bin folder where the .class is generated)
alt text http://ftp.sumylug.osdn.org.ua/pub/mirrors/eclipse.org/downloads/drops/R-3.2-200606291905/new_noteworthy/images/rt-classpath.png
the java needs to refer to that same bin folder, and use the class name (not the class generated binary)
java -cp bin Larger 2 4
To compile javac Large.java
To run java Larger 2 4