import java.util.Arrays;
import java.util.Iterator;
import java.util.ArrayList;
public class Book {
private String book;
private String authorFirstName;
private String authorSecondName;
[Code] ....
i don't understand, the above code generates an error saying that class book is publc, should be declared in a file called book.java. It is. And when the the public modifier is left out of the class it comiles but I then get a load of compile errors java.lang.noclassdefound error.
I have several different PopupWindows that i want to access from the same fragment. I would like for each PopupWindow to be it's own java file. Here is trimmed down code from an example showPopup.java file,
showPopup.java public class showPopup { //public class showPopup extends Activity implements View.OnClickListener{ //public class showPopup extends Window { public static Context appContext; PopupWindow popupWindow; SQLiteDatabase db; EditText edSpeciesLookup,edSpeciesLookupRowid;
[code]...
How do I configure inheritance to allow showPopup() class to reside in it's own Java file and be called from another class (file)? I've reviewed several hours of online resources as well as my reference books with no productive illumination. I've tried a number of possible implementations and extensions such as "public class showPopup extends Activity implements View.OnClickListener{...", and "public class showPopup extends Window.
1.) Is FileReader class the same as File Class. In my book it uses File class to read data from a file, but one of the members here used FileReader so I was wanting to know if it's identical function or not.
2.) When creating an output file, I will use
PrintWriter outputfile("hello.txt")
i just read a new topic of " appending data to a file," meaning if I want to preserve the old file I would have to use this. From my understanding all this does is prevents the old data from being deleted.
Now, in my code if I type ( "hello.txt",true)this would preserve the old data?
The compiler won't let me declare more than one class as "public". Am i correct in understanding that this is a java restriction ? This means i need to create a new file, for each public class that i want in a package ? The rest of the classes without access modifier will all be package-private. (Q has been asked before probably, but my search could not be narrowed).
I am starting to learn java , If suppose we write a simple hello world program
class helloWorld { public static void main(String args[]) { System.out.print("Hello World !"); } }
And save this as test.java.Now after compiling it a helloWorld.class file is generated.But if we compile the same after adding "public" in front of 1st line, it throws error.
public class helloWorld { public static void main(String args[]) { System.out.print("Hello World !"); } }
but then changing the file name to the name of the class i.e. helloWorld.java, corrects the error.
I have got 2 classes in a source file, 1 real class and 1 test class with main() method. While executing with java command which class name should i write - real class or test class???
I am wanting to override certain methods in some Minecraft class files, and tell those class files to use code from my class files.
And no, I don't mean extend a class. When I try to extend from the main Block.Class, it makes that file as another block file for the game, or something.
So like, I want to tell the main file that handles block registries to use the code from my class file to register my custom blocks to the list of blocks, but without modifying that main block file.
Is this even something that's possible?
Also, I know that the way a file is named affects the loading order. My class files would be named using symbols to make it load right before the class file I want to override.
I am having hard time to grasp the concept of java as i am beginner. according to different sources found in internet, only one class is written in one source file. and all those class can be accessed through the main class. my question is
1.can we access one class present in one source file, through another class present in another source file [not through the class containing main method]?
2.can we create more than 1 class in same source file?is there special way to do it? i do get error always when i try to do so 3.can multiple classes contain main method? or should there be only single class containing it?
I'm trying to access class file which is inside the package and package is inside the jar file but I can't access that class file inside my source file . All files are on desktop .
I am trying to create a second class in a single java file (first time trying this) and want to use data from the first class in the second class but I am not able to do it. What am I missing :
package simplecommissioncalculation; import java.util.Scanner; // import java.util.Scanner public class SimpleCommissionCalculation { public static void main(String[] args) {
I've a .java file that won't compile, but produces no errors (in cmd prompt).
I think its the import of java.util.ArrayList thats causing the problem (because it can compile a different file in the same source folder) - so i'm assuming its the classpath that is wrong. which is fine. i love fighting with classpaths.
But why isn't it providing me with an error. the compiler usually goes bat-sh.. crazy if the -cp is incorrect!
Its because I'm switching between command prompt and a text editor and it hadn't saved the file for some reason, and still won't am getting rid of this editor!!
Am facing a very strange issue. While trying to compile a very simple Hello World java program, the compilation completes successfully without any error or warning, but it does not generate the class file.
It happens when I compile with a particular jar file, otherwise compiling only the program (or with any other jar) does generate the class file. I am using java 1.7.0_45.
I have a question about the following snippet concerning the steps the javac compiler follows to compile a program:
[...]at first, searching a class within a package is discussed if the latter doesn't contain a full package name[...]
It is a compile-time error if more than one class is found. (Classes must be unique, so the order of the import statements doesn't matter.)
The compiler goes one step further. It looks at the source files to see if the source is newer than the class file. If so, the source file is recompiled automatically. Recall that you can import only public classes from other packages. A source file can only contain one public class, and the names of the file and the public class must match. Therefore, the compiler can easily locate source files for public classes.
However, you can import nonpublic classes from the current package. These classes may be defined in source files with different names. If you import a class from the current package, the compiler searches all source files of the current package to see which one defines the class. I don't quite understand the red fragment. I wondered if the word "import" nonpublic classes from the current package weren't a synonym for the word "use", since why would we want to import a class from the same package when compiler searches the current package automatically anyway?
However I wanted to test nonpublic classes that are contained in source file which name doesn't match the class name:
NonpublicClass.java:
Java Code:
package com.work.company; class NonpublicClass { public void description() { System.out.println("Working!"); } } mh_sh_highlight_all('java');
[Code] ....
Everything's fine when the source file names are the same as above. However, when I change NonpublicClass.java to a different name, there's an error "cannot find symbol" in:
Java Code: NonpublicClass v = new NonpublicClass(); mh_sh_highlight_all('java');
I noticed that the class file for NonpublicClass isn't even generated so that's probably the cause. If I change to the directory of the package the NonpublicClass is contained in and compile it directly, i.e. issue for example:
I am stuck with my application. I have jsp, servlet application with jasper report server. When I run the application through eclipse, everything works perfectly. But When I try to run it in Tomcat (without eclipse) it gives me the "Unable to resolve the class file " error. I tried all the solutions I got through the google, but still I am unable to come over it.
I extracted a jar file and decompiled one of the classes using jad in order to made a small edit (the original jar was looking to load an image file in the current directory, I replaced the current directory with an environmental variable). I went and recompiled that class. It complained that it cannot find some swt classes, so I downloaded swt.jar for Linux from the Eclipse website and specified the classpath to contain it. It compiled fine and I repacked the jar file. But when I tried to execute it I got:
Java Code: Exception in thread "main" java.lang.NoClassDefFoundError: org/eclipse/swt/widgets/Decorations at java.lang.Class.getDeclaredMethods0(Native Method) at java.lang.Class.privateGetDeclaredMethods(Class.java:2531) at java.lang.Class.getMethod0(Class.java:2774) at java.lang.Class.getMethod(Class.java:1663)
[code]...
I do not get the same error when I execute the original jar file (that complains that it cannot find the image file unless I put the image in the directory I execute it from). I even tried putting swt.jar in the classpath during execution:
I'm trying to load a class file into Oracle using loadjava and I get the following error:
ORA-29552: verification warning: java.lang.UnsupportedClassVersionError: helloworld (Unsupported major.minor version 51.0)
Presumably this is related to an inconsistency between the jdk that I used to compile helloworld and the Oracle JVM? Or something like that?
My JAVA_HOME is C:Program Files (x86)Javajre7bin My javac version used to compile the code is javac 1.7.0_15 java -version is "1.7.0_15" When I do a find on java.exe in the oracle installation directory (I'm running 11.2) I get
