NewBee question - Import statements

Hi,
I am new to Bea workshop.
Can someone help me out in how to add my own Import statements in Java classes
created in workshop.
Thanks and Regards,
Nikita

Hi Nikita,
Welcome to Workshop!
The JWS classes used in Workshop are essentially Java classes with the
additional capability to understand the JWS metatags in the comments.
Hence you can use the import statements in the same manner as you use in a
normal Java class.
Please do let us know if you have any further queries.
Regards,
Anurag
Workshop Support
"Nitika" <[email protected]> wrote in message
news:[email protected]..
>
Hi,
I am new to Bea workshop.
Can someone help me out in how to add my own Import statements inJava classes
created in workshop.
Thanks and Regards,
Nikita

Similar Messages

Newbie question : import statements

So, i'm a complete java newbie trying to make his first swing application, a basic calc. I download NetBeans 6.5, install it, and begin to code. I quickly learn about the Matisse GUI editor, find it very easy to use, and in a couple hours, the work is done and runs very fine.
But looking at my code, I realize I have forgotten all import statements (like import javax.swing, import java.awt.event ....), nevertheless the application runs fine. I suppose then that the Netbeans compiler automatically corrects my mistakes, but I want to do it right.
So, I write the import statements explicitly in my code and I get a warning message : "import unused". After that, I find out about the "fix import" tool in Netbeans, use it and all my import statements disappear. I guess i'm missing something here.
I thought import of swing classes were mandatory to write a swing application. I have NO import statement in my code, even if I'm using jFrames, jButtons, event handlers and the program works fine, why ?
Would I be able to compile this importless code in another environment (let's say Eclipse or even javac) ?
I'm using JDK 1.6 and Netbeans 6.5 with Windows XP.
TIA

glawen wrote:
Ok, thanks for the answers, and sorry for my misinterpretation of BigDaddyLoveHandles's first post. I understand now, the import statements are useful only if you don't want to write full class names, and the generated code uses full class names so no import needed.Please also understand BigDaddyLoveHandles's latest post. If you learn to code Swing with NetBeans' Matisse, then you will be learning Matisse, not Swing. When it comes time to try to tweak or upgrade your program, you will be lost. Better is to learn Swing from the ground up by going through the Sun Swing tutorials. Though having said that, if you are very new to the language, better still is to learn the fundamentals of Java first before embarking in the murky waters of GUI programming. Best of luck to you in your endeavors.

Import statement question

what's the difference between
import java.util.Vector;
and
import java.util.*;
is there any difference in bytecode generated? or time takes to compile?
what's the best practice?

Yes there is a best practice, it's the one you mentioned. Use the more specific import statement. If you're only using one or two classes from a package, explicitly name them in the import statements. That way somebody else reading your code (which includes yourself, six months later) can immediately get a better understanding of your code.
If this rule is followed, and you see this as the first line of a source file:
import java.util.StringTokenizer;
then you know the StringTokenizer is being used. But if you saw this:
import java.util.*;
you wouldn't know which one is being used until you're deep in the code.
Knowing right away whether a class is tokening a string, versus say using collections, makes it a lot easier to read.
You should only use the whole-package include if you're importing a really big part of the package. For example:
import java.awt.*;
is probably OK because it's relatively unlikely a person will use only a couple classes from that package.

Some questions on import statements.

When I see
import java.awt.*
import java.awt.event.*
am I on track interpreting this to mean that you want to be able to use any of the classes found in package java.awt?
why would import java.awt.event.* be necessary if event is a class in the java.awt.* package you're importing in the second import statement up above?
does * mean like a "wildcard" which allows you to utilize
anything that is part of java.awt?

It allows you to use any of the classes in that directory, but not any classes in sub-directories of that directory.

Question about import statements

Why is it that I must have the import statement on the
same frame
and same layer
as the AS code that utilizes the Class that I am importing?
At least that is how it appears.

Because that is how it works.
Remember, import doesn't actually "import" anything. It is
just a shortcut so you don't have to type the whole package name
every time you use the coded in your example.
It is actually kind of nice when you come back to code later
or if you open somebody else's code (that you have to update or
change) and to see at the top, "Oh, this bit of code has a reliance
on class blah.blah.Yadda." In a way it kind of helps enforce a bit
of good coding practice.

Import statement is not working

hi everybody,
I have a directory under which I have a number of sub-directories. Lets call this directory "parent_directory". under this directory I have another directory called "child_1". Under "child_1" I have another subdirectory called "child_2". Now I have a code in child_2 that has the following statement:
import program_1;
//this is a program present in the parent directory. lets call it
//program_1.java
when I am compiling I am getting an error saying:
program_2.java:28: '.' expected
import program_1;
^
1 error
program_2.java is the program present in child_2 in which I have included the import statement.
If I change the ";" to "." then again error appears as the import statement only needs the name of the class and doesnot need the extension.
I will be very grateful to you if you could please suggest me a way around this.

This questions belongs in the "New to Java" forum ...
sigh
Anyways, import works on package names with trailing * or full qualified class names, e.g.import mypackage1.*; // imports all classes in mypackage1
import mypackage2.MyClass2; // imports MyClass2 from mypackage2So instead of import program_1; you need to do
1. ensure that program_1 is in some package
2. ensure that your directory structure mirrors your package structure (same names!)
3. ensure that your CLASSPATH is either not set at all or points to the parent dir of your topmost package
Example:
Directory structure:C:\tmp\java\top\
C:\tmp\java\top\MyClass1.java
C:\tmp\java\top\bottom\
C:\tmp\java\top\bottom\MyClass2.java
CLASSPATH=".;<java install dir>\jre\lib\rt.jar;C:\tmp\java"Source for MyClass1.java:package top;
public class MyClass1 {
}Source for MyClass2.java:package top.bottom;
import top.MyClass1;
public class MyClass2 {
private MyClass1 myClass1;
}

Import statement and directory structure

First of all, sorry for such a long post, I believe part of it is because I am unsure of the concept of importing in Java. Secondly, Thanks to anyone who can ultimately enlighten me to the concept of import. I did ask this question before in the "erorr and error handling" forum, and the people who have helped me there did a great job. But, I believe I require a little more clarification and thus have decided to post here.
Anyhow, my question..
Could someone explain to me the concept of the import statement, or direct me to a webpage with sort of explanation for newbies? For some reason, I am having a hard time grasping the concept.
As I understand it, the import statement in Java, is very similar to the namespace keyword in C. That is to say, import doesn't actually "import" any source code, the way that the #include statement does in C.
So I suppose what my question is, say I have a java class file like below:
//filename: sentence.java
//located: c:\school\csc365
package csc365;
class sentence
//some variables here..
//some constructor here..
//some methods here..
And some sample program like the one below which implements the above..
//filename: test.java
//located: c:\school\csc365
import csc365.*;
import java.io.*;
class test.java
//creates some sentence object
//uses the object's methods
//some other things.
As I understand it, the test.java file should not compile because the csc365 package is not in the correct directory. (assuming of course, the classpath is like c:\school\csc365;c:\school )
But, ... where then should the sentence.java be located? In a subdirectory of c:\school called csc365 (i.e c:\school\csc365\) ?
And thus that would mean the test.java file could be located anywhere on the hard drive?
I suppose, I just need a little clarification on the correlation between a package's "name" (i.e package csc365; ) and its corresponding directory's name, and also how the javac compiler searches the classpath for java classes.
..So, theoretically if I were to set the classpath to look in every conceivable directory(provided the directory names were all unique) of the harddrive, then I could compile a test.java anywhere?
As a note: I have been able to get the test.java file to compile, by leaving out the import statement in the test.java file, and also leaving out the package statement for the sentence class, but I assume this is because the files are defaulted to the same package?

Hi Mary,
No, import isn't analogous to C++ namespace - Java package is closer to the namespace mark.
import is just a convenience for the programmer. You can go your whole Java career without ever writing an import statement if you wish. All that means is that you'll have to type out the fully-resolved class name every time you want to use a class that's in a package other than java.lang. Example:
// NOTE: No import statements
public class Family
   // NOTE: fully-resolved class names
   private java.util.List children = new java.util.ArrayList();
}If you use the import statement, you can save yourself from typing:
import java.util.ArrayList;
import java.util.List;
public class Family
   // NOTE: fully-resolved class names
   private List children = new ArrayList();
}import isn't the same as class loader. It does not bring in any source code at all.
import comes into play when you're compiling or running your code. Java will check to make sure that any "shorthand" class names you give it live in one of the packages you've imported. If it can't find a matching fully-resolved class name, it'll give you a message like "Symbol not found" or something like that.
I arrange Java source in a directory structure that matches the package structure in the .class files.
If I've got a Java source file like this:
package foo.bar;
public class Baz
   public static void main(String [] args)
        Baz baz = new Baz();
        System.out.println(baz);
   public String toString()
       return "I am a Baz";
}I'll store it in a directory structure like this:
root
+---classes
+---src
      +---foo
           +---bar
                +---Baz.javaWhen I compile, I go to root and compile by typing this:
javac -d classes foo/bar/*.javaI can run the code from root by typing:
java -classpath classes foo.bar.BazI hope this wasn't patronizing or beneath you. I don't mean to be insulting. - MOD

Unused packages in import statement

Guyz,
Can anyone throw some light on this ?
Does using a lot of unused packages in import statement of a jsp affects its performance in terms of page loading ?
Thanks.

I have just found the answer for my question in another forum.
Please visit:
http://saloon.javaranch.com/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic&f=15&t=000240
Thanks.

Confused about CLASSPATH and how java handles import statements...

Hello,
I must admit I don't get it. I read the articles about setting CLASSPATH etc. but I still wonder:
If you use an import statement, what does the compiler do? I.e. where does it look for the specified classes? I find it confusing because I see in different locations different .jar files:
C:\jdk1.3.1_03\lib\dt.jar
C:\jdk1.3.1_03\lib\htmlconvertor.jar
C:\jdk1.3.1_03\lib\tools.jar
and also
C:\jdk1.3.1_03\jre\lib\i18n.jar
C:\jdk1.3.1_03\jre\lib\rt.jar
C:\jdk1.3.1_03\jre\lib\jaws.jar
C:\jdk1.3.1_03\jre\lib\sunrassign.jar
Can someone explain me what the purpose is of these files?
And why do I have the same contents in
C:\Program Files\JavaSoft\JRE\1.3.1_03\lib
and in
C:\jdk1.3.1_03\jre\lib
Why is that?
Thanks for answering my questions!
-mike

Thanx for the answers, but I still wonder, everyone
here says I need to set the classpath, but I don't.Probably because your classes are already in the class path. The compiler/jvm also look for classes by themselves not just in jar files, when just a directory is supplied in the class path. And a period (".") is a valid directory.
Programs importing different classes compile with no
problem. So what's up with that?
Presumably you are referring to your own code - because they are in the class path.
Second, I still don't understand why the runtime needs
the .jar files. The runtime uses classes, like String, that have to come from somewhere.
This would also mean that end-users
need to set the classpath to the .jar files in their
JRE directory to be able to run programs that import
classes from these .jars. But this is not true, right?No it is true. The end-users will have to set the class path. There are variations on this which make it seem like no class path is set. For instance applets in a browser are java but the end-user does not need to set a class path. That is because the browser knows how to download classes/jars and how to set it up so it uses them. (Actually it uses a class loader, but that is probably more information that you need.)
Because if I make some nice classes myself and import
them, how can I expect my end-user to install these
classes and make a classpath for them?That would be between you and you end-user.
First installation is not part of java. For installation you will have to find something outside of java to accomplish the goal.
Additionally how the class path gets set is OS specific. Java does not deal with that. You will also have to find some way to deal with this (most likely part of the installation.)
There are also variations on this. For example the browser example I gave above. Or using the ext directory. Or creating an executable jar. Or simply setting the class path.
In my understanding it should only be needed in the JDK, not
in the JRE. True or am I mistaken?Mistaken. The class path is needed in the JRE as well. You will need to set it.

What is import statement for ?

Hi all,
Sorry for asking a silly question. Since it is a new to java forum I am asking this.
What is happening when an import statement is triggered at compile time and at runtime.
What is the difference/advantages/disadvantages between importing an entire package and importing required classes only.
Is there any size limit on the generated class file.
rgds
Antony Paul

looks like we are both beguinners
i just received a newsletter from sun and in it has this
MONITORING CLASS LOADING AND GARBAGE COLLECTION
Have you ever wondered what classes are loaded when you launch an application or from where the classes are loaded? Have you ever wondered when garbage collection runs or how long it takes? The java command line tool offers several different command line options that you can use to get answers to those questions.
You might already be familiar with a number of command line options available with the java command line tool, such as -cp, -Xms, and -Xmx. The -cp option is used for specifying the classpath. The -Xms and -Xmx options are used to specify the heap size. For example, instead of setting the CLASSPATH environment variable, you can use the -cp option to tell the system to look in a specific directory for necessary class files:
java -cp ExampleDir MyExample
Here, the system will look in the ExampleDir subdirectory for the MyExample.class file and anything else needed besides the system classes. The ExampleDir in the command line tells the system to look only in the ExampleDir directory (assume that it's the parent directory). If MyExample.class is located in the current working directory, the system would not find it.
Two less frequently used command line features report on class loading and garbage collection. The -verbose:class option reports when a class is loaded into the Java virtual machine and from where it came. For instance, if you use the -verbose:class option when loading the SwingSet2 demo that comes with the J2SE 1.4.2 SDK, you get a report on the many different classes that are loaded as part of the demo, such the following two:
java -verbose:class -jar
C:\j2sdk1.4.2\demo\jfc\SwingSet2\SwingSet2.jar
[Loaded FilePreviewer]
[Loaded javax.swing.plaf.TableUI from
C:\j2sdk1.4.2\jre\lib\rt.jar]
The first line indicates that the class came from the main JAR for the demo (assuming it was started with java -jar SwingSet2.jar). The second line indicates that the TableUI class was loaded from the rt.jar file that comes with the runtime located in the c:\j2sdk1.4.2\jre directory. (From there, the rt.jar file is located in the lib subdirectory.) Different implementations of the Java platform can have different formats here. The only requirement is that -verbose:class displays messages as classes get loaded and unloaded.
Let's see when classes are loaded, and how many classes are needed for the following simple program:
public class Sample {
public static void main(String args[]) {
System.out.println("Hello, World");
Compile the Sample class. Then run it with the -verbose:class option enabled:
java -verbose:class Sample
When you run the command, you'll see that this simple program requires the opening of five jar files (such as rt.jar) and the loading of almost 250 classes.
To see an example of a class unloading message, try the -verbose:class command line option with the RunItReload class shown in the August 19, 2003 Tech Tip titled Unloading and Reloading Classes.
The -verbose:gc option reports on each garbage collection event. This includes the time for garbage collection to run, and the before and after heap sizes. This is demonstrated in the following lines:
[GC 27872K->26296K(42216K), 0.0069590 secs]
[GC 28973K->26455K(42216K), 0.0036812 secs]
[GC 29134K->26474K(42216K), 0.0016388 secs]
[GC 29117K->26487K(42216K), 0.0008859 secs]
[GC 29134K->26498K(42216K), 0.0009197 secs]
[GC 29180K->26479K(42216K), 0.0008711 secs]
[GC 29149K->26484K(42216K), 0.0008716 secs]
Like the output for -verbose:class, there is no requirement for output format, and it is subject to change without notice. The "GC" at the beginning indicates what kind of collection occurred. The number before the "->" is the heap occupancy before the collection. The number after the "->" is the heap occupancy after the collection. The number in parentheses is the currently allocated size of the heap. The seconds are the duration of the collection.
This information can be useful in debugging. For example, it could help you determine if garbage collection happened at a critical point in time, and might have caused a program to crash. This sometimes happens when mixing Java and C/C++ code with JNI, especially when there is an underlying bug on the C/C++ code side.
If you're ever curious about why it takes so long for an application to start, or if garbage collection in the middle of an operation appears to cause a problem, be sure to try out these command line options.
hope it helps

Using Import Statement

Hi,
I understand that in order to access the methods of a different class, I can "import" it. Here is my question though:
Where am I importing it from? I mean, surely if I am importing a class from e.g. the Java.util package, doesn't this package need to be on my computer somewhere?
And also, if I make a .jar file of my application for use on another computer and the files contain import statements, doesn't the other computer need to have these packages on their machine?
I know this seems like a silly question but it's bothering me!
GF

Yep, you can unzip them to see inside. The package name unzips into a directory structure and the Class name is a file. So java.util.HashMap will unzip into a directory java/util and have a file called HashMap.class in it.
You can usually download the source code for these classes also.

Basic import statement

I have a question whenever I want to print out any string, value, I always use
System.out.println("some string");
System.out.print("some string");
System.out.printf("%s", "some string");my question is: is there anyway that I can write shorter code?
.out.println("hihi") or just .println("hihi"); I think there must be something to do with the import statement, but just I cant get it to work.

DO NOT do this. Your laziness will result in unreadble code for others. Anyone who looks at your code will know what System.out.println() means. Whereas they do not know what someObscureMethodName() is or does.

Difference Betwen #include statement and Import statement

What is the Difference between #include and Import statements!

Why do you need to shout! Are you unware that English has a question mark that is used at the end of a question sentence! Java doesn't have #include! It only has import!
Import in Java simply tells the compiler that when you say, for example, List, you mean, for example, java.util.List! It does not affect the generated class file in anyway!
#include in C/C++ causes the body of the reference file to be inserted into the compilation stream! So, unlike Java's import, that file actually gets compiled into the final output!

Cannot resolve import statements

I recently decided to start messing around with some Java3d. I tried to get an example program to try to dissect but I can't even get past compilation. The main problem is the fact that the import statements cannot be resolved. I thought maybe I was using an outdated example program but upon further inspection of Oracle's own Java3d tutorials I saw the same import statements. I downloaded java3d 1.5.1 because I thought perhaps it wasn't included in the java core classes. This did not help me at all. So maybe it is a problem with the IDE (eclipse) not recognizing them. However, I have had no such success with Google thus far. I realize that this is more than likely a horribly simple mistake that anyone over a novice understanding of Java would be able to spot. But if anyone could help me figure out why I can't compile it would be much appreciated.
Regards,
Corey
Import statements that would not resolve
import com.sun.j3d.utils.geometry.GeometryInfo;
import com.sun.j3d.utils.geometry.NormalGenerator;
import com.sun.j3d.utils.universe.SimpleUniverse;
import javax.media.j3d.*;
import javax.vecmath.*;Full program
import java.awt.Color;
import com.sun.j3d.utils.geometry.GeometryInfo;
import com.sun.j3d.utils.geometry.NormalGenerator;
import com.sun.j3d.utils.universe.SimpleUniverse;
import javax.media.j3d.*;
import javax.vecmath.*;
// An Egyptian pyramid
// Base divided into two triangles
public class PyramidExample {
     public static void main(String[] args) {
          SimpleUniverse universe = new SimpleUniverse();
          BranchGroup group = new BranchGroup();
          Point3f e = new Point3f(1.0f, 0.0f, 0.0f); // east
          Point3f s = new Point3f(0.0f, 0.0f, 1.0f); // south
          Point3f w = new Point3f(-1.0f, 0.0f, 0.0f); // west
          Point3f n = new Point3f(0.0f, 0.0f, -1.0f); // north
          Point3f t = new Point3f(0.0f, 0.721f, 0.0f); // top
          TriangleArray pyramidGeometry = new TriangleArray(18,
                    TriangleArray.COORDINATES);
          pyramidGeometry.setCoordinate(0, e);
          pyramidGeometry.setCoordinate(1, t);
          pyramidGeometry.setCoordinate(2, s);
          pyramidGeometry.setCoordinate(3, s);
          pyramidGeometry.setCoordinate(4, t);
          pyramidGeometry.setCoordinate(5, w);
          pyramidGeometry.setCoordinate(6, w);
          pyramidGeometry.setCoordinate(7, t);
          pyramidGeometry.setCoordinate(8, n);
          pyramidGeometry.setCoordinate(9, n);
          pyramidGeometry.setCoordinate(10, t);
          pyramidGeometry.setCoordinate(11, e);
          pyramidGeometry.setCoordinate(12, e);
          pyramidGeometry.setCoordinate(13, s);
          pyramidGeometry.setCoordinate(14, w);
          pyramidGeometry.setCoordinate(15, w);
          pyramidGeometry.setCoordinate(16, n);
          pyramidGeometry.setCoordinate(17, e);
          GeometryInfo geometryInfo = new GeometryInfo(pyramidGeometry);
          NormalGenerator ng = new NormalGenerator();
          ng.generateNormals(geometryInfo);
          GeometryArray result = geometryInfo.getGeometryArray();
          // yellow appearance
          Appearance appearance = new Appearance();
          Color3f color = new Color3f(Color.yellow);
          Color3f black = new Color3f(0.0f, 0.0f, 0.0f);
          Color3f white = new Color3f(1.0f, 1.0f, 1.0f);
          Texture texture = new Texture2D();
          TextureAttributes texAttr = new TextureAttributes();
          texAttr.setTextureMode(TextureAttributes.MODULATE);
          texture.setBoundaryModeS(Texture.WRAP);
          texture.setBoundaryModeT(Texture.WRAP);
          texture.setBoundaryColor(new Color4f(0.0f, 1.0f, 0.0f, 0.0f));
          Material mat = new Material(color, black, color, white, 70f);
          appearance.setTextureAttributes(texAttr);
          appearance.setMaterial(mat);
          appearance.setTexture(texture);
          Shape3D shape = new Shape3D(result, appearance);
          group.addChild(shape);
          // above pyramid
          Vector3f viewTranslation = new Vector3f();
          viewTranslation.z = 3;
          viewTranslation.x = 0f;
          viewTranslation.y = .3f;
          Transform3D viewTransform = new Transform3D();
          viewTransform.setTranslation(viewTranslation);
          Transform3D rotation = new Transform3D();
          rotation.rotX(-Math.PI / 12.0d);
          rotation.mul(viewTransform);
          universe.getViewingPlatform().getViewPlatformTransform().setTransform(
                    rotation);
          universe.getViewingPlatform().getViewPlatformTransform().getTransform(
                    viewTransform);
          // lights
          BoundingSphere bounds = new BoundingSphere(new Point3d(0.0, 0.0, 0.0),
                    1000.0);
          Color3f light1Color = new Color3f(.7f, .7f, .7f);
          Vector3f light1Direction = new Vector3f(4.0f, -7.0f, -12.0f);
          DirectionalLight light1 = new DirectionalLight(light1Color, light1Direction);
          light1.setInfluencingBounds(bounds);
          group.addChild(light1);
          Color3f ambientColor = new Color3f(.4f, .4f, .4f);
          AmbientLight ambientLightNode = new AmbientLight(ambientColor);
          ambientLightNode.setInfluencingBounds(bounds);
          group.addChild(ambientLightNode);
          universe.addBranchGraph(group);
}

Hi,
- The latest Java 3D release is *1.5.2*. Uninstall older versions.
- Java 3D home: http://java3d.java.net/
- Java 3D project: http://java.net/projects/java3d
- Java 3D downloads: http://java3d.java.net/binary-builds.html
- Start with one of the Java 3D examples from "j3d-examples-1_5_2-src.zip"
- Use eclipse *3.6.2*, it should recognize Java 3D's jars if they are installed in '..\jre\lib\ext\'. See also Java3D + Newer Eclipse Version -> Access Restriction (solution + question)
August

Filename in import statement

Hi srinivas bobbala,
Thank you for your response.But I think my quesition was not clear.My ques... is for suppose there is one datafile for importing like.. "datafile_21" Here my intention is it takes file from datafile_21 only but it appears in import statement like datafile_21<<curmon>>.
import database sample.sample data from data_file "c:\\ABC\datafile_21_AUG.txt" using server rules_file datafile on error abort;
In this it takes datafile from datafile_21.But it appears like datafile_21_AUG in import statement.This AUG coming from batch file.
Essmsh c:\\ABC\loadmxl.mxl %curmon%

No it is not possible.
I assume the data file "datafile_21" is first renamed to datafile_21_${CurrMth} in the batchscript.
After that this data file *datafile_21_${CurrMth}* is pointed in the import statement.
In the logs you will see this file as datafile_21_Aug.

NewBee question - Import statements

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