I started learning Java lately, and trying to make my first program based on book which is the "Hello World" program.
After writing the script on notepad, i try to compile it on the command prompt and then this notice appeared.
first I type: javac javaCode.java
then there a notice said:
javaCode.java:2: error: <identifier> expected
public class static void main(string[] args) {
^
javaCode.java:6: error: reached end of file while parsing
}
^
2 errors
I don't have any ideas what going on here so please give detailed information and how to fix this thing.
public class static void main(string[] args)
Remove class
public static void main(string[] args)
class is different from method. main method syntax doesn't contain class.
Your main method needs to go inside a class: Java won't let you do things any other way.
Try:
public class HelloWorld{
public static void main (String[] args){
//your code goes here
}
}
this the basic structure for a simple program like this.
the class identifier, has to be on the declaration of the class.
public class Caculator {
public static void main(String[] args) {
// Your code here
}
}
It probably should be:
public class JavaCode {
public static void main(String[]args){
}
}
That should do it. ;)
Related
File Name = multiple_main_methods.java
class multiple_main_methods_two {
public static void main(String[] args){
System.out.println("Class second");
}
}
class multiple_main_methods_one {
public static void main(String[] args){
System.out.println("Class first");
}
}
Output
Class first
IDE used - IntelliJ IDEA
IntelliJ is choosing a class to execute.
Remember, you execute the main method in a class, not in a file.
Check it in your Run configurations
enter image description here
It is not giving error because your main methods belong to different classes i.e. multiple_main_methods_two and multiple_main_methods_one which is completely fine.
//: innerclasses/TestBed.java
// Putting test code in a nested class.
// {main: TestBed$Tester}
public class TestBed {
public void f() { System.out.println("f()"); }
public static class Tester {
public static void main(String[] args) {
TestBed t = new TestBed();
t.f();
}
}
} /* Output:
f()
*///:~
I am studying "Think in Java". I am just wondering why the above code doesn't work which should be a way to test each class, and can be removed by deleting TestBed$Tester.class file.
The error msg instructs there should be a public static void main(String[] args) in TestBed class as program entry.
java compile version: javac 1.7.0_40
The main method must be in the public top-level class. That is the one with the same name as the java-file. Here, that's the TestBed-class.
The current main method is in an inner class (namely TestBed$Tester), and can't be used to start a program.
EDIT: I may have been wrong. I took a look in the book you mentioned, and it looks like you're able to run the inner class from the Command Promt by writing:
java TestBed$Tester
Was just testing a simple code, and it appears my eclipse just got worse. This code is suppose to output 2. But when I run it, very weird error says 'Error: Main method not found in class jasc1, please define the main method as: public static void main(String[] args)' when my main method is clearly defined.
Does anyone know what this error is all about??
public class jasc1 {
int a = 2;
public void abc(){
System.out.print(a);
}
public static void main(String[] args){
new jasc1().abc();
}
}
This works fine for me, your file name must be wrong. It MUST be the same as the class name.
Additionally
Class names should (by convention) begin with an upper case letter so Jasc1
If you want to execute a class It should have a method public static void main(String [] args) (or similar meanings). But, for executing a class you have to run that class.
ex: In command line you call java jasc1 after compiling it with javac jasc1.java (ofcourse there are some options like -cs; see help)
The same way you can run one class in Eclipse or NetBeans IDEs by right-clicking on it in the project explorer and select Run or Run as
Of course, this jasc1 class cannot call another class that have a public static void main(String []args) method.
I was trying to know what would happen if I have two classes with the main function.
I used the following code:
class A {
public static void main(String[] args){
System.out.println("Hello,World!");
}
}
class Hello {
public static void main(String[] args){
System.out.println("Hello,World!");
}
}
I compiled it using javac First.java (since no class is specified as public , I named the file as First.java); it got compiled without any error and i ran only the class A.Expecting the Hello class to run itself. DIDN'T HAPPEN(?),maybe the program ran out of scope.
So,
I tried compiling the following java code(I am a beginner) but i got the following error.
Code:
class Hello {
public static void main(String[] args) {
System.out.println("Hello,World!");
}
}
class A {
public static void main(String[] args) {
System.out.println("Hello,World!");
Hello.main();
}
}
I compiled it through javac First.javaand got the following error:
method main in class Hello cannot be applied to given types;
Hello.main();
^
I wanted the program to run first the class A's main function and then class Hello's.
What's going wrong here?
Look at the declaration of Hello.main:
public static void main(String[] args)
Now you're trying to call it like this:
Hello.main();
What would you expect the value of args to be, within the method? You need to provide it with a value for args... and fortunately, you already have one, as you're within a method which uses args as a parameter, also of type String[]. So you should just be able to change your code to:
Hello.main(args);
Note that the two args parameters - one for Hello.main and one for A.main are entirely separate. We happen to use pass the value of one to the provide the initial value for the other, but we could easily have written:
Hello.main(null);
or
Hello.main(new String[] { "Some", "other", "strings" });
instead.
Do this in your second class:
public static void main(String[] args) throws IOException {
MyOtherClass.main(args);
}
Pretty new to Java programming, but I'm having trouble getting this to run. I want to read in a word using the StringBuffer class, then reverse it. I am fairly unfamiliar with importing Java libraries, so I'm not sure if I did that correctly. Either way, this is what I have. I tried to compile it (I'm working in the Terminal), but got a few compiler errors. Any help would be appreciated.
import java.util;
import java.io;
public class HW1A {
public static void main (String[] args) {
printBackwards();
}
public static void printBackwards (String[] args) {
StringBuffer backwards = new StringBuffer(args);
System.out.println(backwards.reverse());
}
}
I get the following complier errors:
HW1A.java:1: cannot find symbol
symbol : class util
location: package java
import java.util;
^
HW1A.java:2: cannot find symbol
symbol : class io
location: package java
import java.io;
Thanks.
Since this is a learning exercise have a look at printBackwards, and ask yourself:
What parameters does it need and what are you passing?
Then look at this and what StringBuffer needs - do these match?
Two corrections:
import java.io.*;
To import everything in java.io.
And:
printBackwards(args);
To pass args to your printBackwards method (you declared it correctly, but didn't pass the variable).
The method printBackwards takes a String[] as an argument, but you're not passing anything when you call it.
This compiles :
public class HW1A {
public static void main (String[] args) {
printBackwards(args);
}
public static void printBackwards (String[] args) {
StringBuffer backwards = new StringBuffer(args[0]);
System.out.println(backwards.reverse());
}
}
But you have to decide if the argument to pass to create the StringBuffer is the first element of the args array.
No compilation error... but not sure this is what you want to do...
public class HW1A {
public static void main (String[] args) {
printBackwards(args);
}
public static void printBackwards (String[] args) {
StringBuffer backwards = new StringBuffer();
for (int i = 0; i < args.length; i++) {
backwards.append(args[i]);
}
System.out.println(backwards.reverse());
}
}
Parameters: Hello world!
Output: !dlrowolleH