At school, I write Java programs with Windows’ Java Editor (console mode). There, InOut.readInt() (used for user input) works without problems and I don’t have to import anything.
Now, I have a Java homework for the holidays, and I try to write Java programs on my Mac. In online console Java editors, the line InOut.readInt() causes this error:
/IntBetween10And100.java:8: error: cannot find symbol
int input = InOut.readInt("Integer --> ");
^
symbol: variable InOut
location: class IntBetween10And100
1 error
I already tried import lines (placed before the class) like:
import java.*
import java.util.*
import java.util.InOut
import java.io.BufferedStreamReader
import java.util.*;
public class IntBetween10And100 {
public static void main(String args[]) {
int input = InOut.readInt("Integer --> ");
}
}
int input = InOut.readInt("Integer --> ");
should produce the line
Integer -->
but instead, the error message (seen above) appears.
OK, so you are using the "Java-Editor" tool on Windows for writing your Java code.
It turns out that Java-Editor includes a class called InOut as an example class. (You can see it here: http://javaeditor.org/doku.php?id=en:examples).
For various reasons, it is not suitable for use in production code of any kind:
It is not part of the Java SE class library, or any 3rd-party libraries.
It is a class in the default package
It has limited functionality, even compared to the real System.in and System.out
It would interfere with any application or 3rd party library code that uses System.in in the normal way. (It creates its own BufferedReader to wrap System.in. That is liable to capture "type-ahead" input.)
You don't really need to use it for educational purposes either. It is only a wrapper class ...
However, if you want to use InOut outside of the Java-Editor context, you could simply download the source code from the page above and add it to your project. I can't tell you exactly how, but adding classes should be explained in the documentation of the tool you are using now! (If you are serious about learning Java, I would actually recommend that you download and install a real Java JDK and a real Java IDE on your own computer.)
The authors have neglected to include an explicit copyright notice in the InOut.java file. However, the Java-Editor site as a whole is licensed as "CC Attribution-Share Alike 4.0 International".
Related
I was looking at this video to find some information on making Minecraft Plugins. https://youtu.be/r4W4drYdb4Q
All plugins are made with Java. Since I program with Python I was wondering if it is possible to make a Plugin similar to the one seen in the video but with Jython. I am not sure if this is possible but I started trying.
When programming Java most people use Eclipse and there is a button that says "Add external Jar" and that is where you input the spigot jar file. From what I understand I can do that with:
import sys
sys.path.append("spigot-1.15.2.jar")
in Jython. Then there comes the tricky part. How would I go about converting this:
Code Part 1
Code Part 2
From what I thought I needed to do was something like:
from org.bukkit.plugin.java import JavaPlugin
class Main(JavaPlugin):
def onEnable():
pass
#what do I put here?
def onDisable():
pass
#what do I put here?
But I don't think I am properly converting the Java code to Jython. What would be the proper way to convert the code from Java to Jython?
Thanks very much!
From my understanding you want to interact from your Jython code with a Java class which extends JavaPlugin.
For this I suggest you write a thin wrapper in Java which then calls your Jython code where you do the heavy lifting in your familiar language. A skeleton of the wrapper could look like this:
package {$GroupName}.{$ArtifactName};
import org.bukkit.plugin.java.JavaPlugin;
import org.python.util.PythonInterpreter;
public final class {$ArtifactName} extends JavaPlugin {
#Override
public void onEnable() {
PythonInterpreter pi = new PythonInterpreter();
pi.execfile("enable.py"); // enable.py is the Jython file with the enable stuff
}
#Override
public void onDisable() {
PythonInterpreter pi = new PythonInterpreter();
pi.execfile("disable.py"); // enable.py is the Jython file with the disable stuff
}
}
Be aware that instantiating PythonInterpreter is rather slow, so you'd be better off with a pattern where you do this only once. Plus then you can share data between enable and disable!
For more details and other options (like having the Jython stuff in one file and calling into it via pi.exec) look at Chapter 10: Jython and Java Integration in the Jython Book.
Also keep in mind when coding away: Jython is only Python 2.7!!!
So I want to make a java application in eclipse which the user i will be able to import .zip files. Each .zip file will represent a cat breed. I will click on a "train" button and my program will contact IBM Watson services and create a classifier. Then from a different window, i will import random cat images and the program will show what cat breed is in the image. Everything with the SDKs is fine since I ran some examples from the official Watson site and everything ran smoothly. Problem comes when I try to create my own classifiers. The code you are about to see is also from their site. For some reason the createClassifier method won't take the CreateClassifierOptions object as an argument.
import java.io.File;
import com.ibm.watson.developer_cloud.http.ServiceCall;
import com.ibm.watson.developer_cloud.speech_to_text.v1.model.RecognitionCallback;
import com.ibm.watson.developer_cloud.visual_recognition.v3.*;
import com.ibm.watson.developer_cloud.visual_recognition.v3.model.*;
public class TrainningClassifier{
public static void main(String[] args) {
VisualRecognition service = new VisualRecognition(
VisualRecognition.VERSION_DATE_2016_05_20
);
service.setApiKey("aca4433597018de62edafdeebceb2bdc1482496a");
CreateClassifierOptions createClassifierOptions = new CreateClassifierOptions.Builder()
.name("dogs")
.addClass("beagle", new File("./beagle.zip"))
.addClass("goldenretriever",new File("./golden-retriever.zip"))
.addClass("husky", new File("./husky.zip"))
.negativeExamples(new File("./cats.zip"))
.build();
Classifier dogs = service.createClassifier(createClassifierOptions).execute();
System.out.println(dogs); /*error is in the above line.
the createClassifier method.*/
}
}
Error: Exception in thread "main" java.lang.Error: Unresolved
compilation problem: The method createClassifier(ClassifierOptions)
in the type VisualRecognition is not applicable for the arguments
(CreateClassifierOptions)
at testVisualRec.ForAssignment.main(ForAssignment.java:31)
Any ideas?
Found the solution. For some reason eclipse wouldn't recommend this solution I had to experiment. I just added throws IOException in main method. I also put inside the main method System.out.println(new File(".").getAbsoluteFile()); to make sure the path was correct, and it was. (SDK used for this project is 4.0.0, not the newest one. SDK found here: https://github.com/watson-developer-cloud/java-sdk/releases)
Installation instructions: http://docs.opencv.org/doc/tutorials/introduction/desktop_java/java_dev_intro.html
I have downloaded everything. Everything seems to be working except when I run this sample program:
import org.opencv.core.Core;
import org.opencv.core.CvType;
import org.opencv.core.Mat;
public class Main {
public static void main(String[] args) {
System.out.println("Welcome to OpenCV " + Core.VERSION);
System.loadLibrary(Core.NATIVE_LIBRARY_NAME);
Mat m = Mat.eye(3, 3, CvType.CV_8UC1);
System.out.println("m = " + m.dump());
}
}
I get the output:
m = [1, 0, 0;
0, 1, 0;
0, 0, 1]
(which I hope is right).
But I also get these error messages:
objc[63784]: Class CVWindow is implemented in both /Users/.../cv2.so and /Users/... /libopencv_java246.dylib. One of the two will be used. Which one is undefined.
objc[63784]: Class CVView is implemented in both /Users/.../cv2.so and /Users/.../libopencv_java246.dylib. One of the two will be used. Which one is undefined.
objc[63784]: Class CVSlider is implemented in both /Users/.../cv2.so and /Users/.../libopencv_java246.dylib. One of the two will be used. Which one is undefined.
objc[63784]: Class CaptureDelegate is implemented in both /Users/... /cv2.so and /Users/jsuit/opencv/lib/libopencv_java246.dylib. One of the two will be used. Which one is undefined.
I have tried moving the cv2.so file to another folder, but then the program won't compile.
The problem has to do, as far as I can make out, with a reference to the Python libraries (the .so version) that ends up included within the Java libraries themselves. This would seem to be a build configuration error (following the instructions does produce it).
I was able to eliminate the double-definition error by re-building the Java version without support for the Python libraries in it, using the following in the cmake step (all else the same):
cmake -D BUILD_SHARED_LIBS=OFF -D BUILD_NEW_PYTHON_SUPPORT=NO ..
The newly produced Java libraries and .jar work just as before, but without the error message.
(Note that I can't guarantee this won't cause other problems, especially if you want to do some sort of mixed-language programming, but it does produce libraries useful for Java and Eclipse. You can always build multiple versions of OpenCV, too, some with support for Python, some without, and use whichever one you like if you switch languages at some point.)
Hat tip: http://answers.opencv.org/question/16015/mac-opencv-246-java-exception/
I'm working on java application which perform some Runtime sub-process on files, for some files I got error cause the Send error report to Microsoft window to appear ,I need to handle this error programmatically, without showing this window to user. Please can anyone help ?
To Suppress windows error reporting the .exe that is being invoked should not terminate with an unhandled exception. This only works if you have access to the source of the application.
Based on the WER Reference - you should use the Win32 API call WerAddExcludedApplication to add the specific .exe files that you are intending to ignore to the per-user ignore list - you could create a simple stub-application that allows you to add applications by name to the ignore list. Then when you invoke the application it does not trigger the error.
Similarly you could create another application to remove them using the WerRemoveExcludedApplication.
Alternatives are to use JNI/JNA to make a class to encapsulate this functionality rather than using Runtime.exec
Here is a simple example using Java Native Access (JNA), which is a simpler version of JNI (no C++ needed for the most part). Download the jna.jar and make it part of your project.
import com.sun.jna.Native;
import com.sun.jna.WString;
import com.sun.jna.win32.StdCallLibrary;
public class JNATest {
public interface CLibrary extends StdCallLibrary {
CLibrary INSTANCE = (CLibrary) Native.loadLibrary("wer.dll",
CLibrary.class);
int WerAddExcludedApplication(WString name, boolean global);
int WerRemoveExcludedApplication(WString name, boolean global);
}
public static void main(String[] args) {
CLibrary.INSTANCE.WerAddExcludedApplication(new WString("C:\\foo.exe"), false);
CLibrary.INSTANCE.WerRemoveExcludedApplication(new WString("C:\\foo.exe"), false);
}
}
Basically, replace the new WString(...) value with the name of the application that you are intending to ignore. It should be ignored for the purposes of windows error reporting at that point.
Bear in mind that the wer.dll is only on Windows Vista and newer, so if this is a problem, then you may need to edit the registry entries manually.
You can always use try-catch-finally statement:
try
{
some code here (the code that is causing the error);
}
catch (Exception x)
{
handle exception here;
}
It works for me...
EDIT Here is the link that can help you a little bit more:
http://www.exampledepot.com/egs/Java%20Language/TryCatch.html
I'm using this code:
for (final String code : Locale.getISOCountries())
{
//stuff here
}
But on compile I get this error:
[ERROR] Line 21: No source code is available for type java.util.Locale; did you forget to inherit a required module?
And then a stack trace of compiler errors.
I'm doing both of these imports at the beginning of the class:
package com.me.example;
import java.util.Locale;
import java.util.*;
What can be wrong?
In Netbeans i see the autocomplete options and no syntax error for the Locale object...
Something screwy with your setup, the folllowing program works fine for me.
import java.util.*;
import java.util.Locale;
public class Donors {
public static void main (String [] args) {
for (final String code : Locale.getISOCountries()) {
System.out.println (code);
}
}
}
The fact that it's asking for source code leads me to believe that it's trying to compile or run it in some sort of debugging mode. You shouldn't need the source code for java.util.* to compile, that's just bizarre.
See if my simple test program works in your environment, then try looking for something along those lines (debugging options). Final step: compile your code with the baseline javac (not NetBeans).
UPDATE:
Actually, I have found something. If you are creating GWT applications, I don't think java.util.Locale is available on the client side (only the server side). All of the references on the web to this error message point to GWT and its limitations on the client side which are, after all, converted to Javascript goodies, so cannot be expected to support the entire set of Java libraries.
This page here shows how to do i18n on GWT apps and there's no mention of java.util.Locale except on the server side.
Looks like there might be something fishy in your build environment, as Locale.getISOCountries() should work just fine. Try compiling a small test program manually and see if you get the same error.
Definitely try to boil this down to a minimum, three-line program (or so), compile from the command-line, then put that class into your IDE and see if you still get the error, and if not, then change/add one line at a time until you have the original failing program, looking for what causes the problem. I'm thinking maybe some other import in your code is importing a Locale class? Why in the world would it be looking for source code?
See what happens when you compile this from the command-line:
import java.util.*;
public class LocaleTest {
public static void main(String[] args) {
Locale.getISOCountries();
}
}