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JAVA PROGRAMME |
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Java Basics
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Working with Objects
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Arrays, Conditionals, and Loops
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Creating Classes and Applications in Java
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More About Methods
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Java Applet Basics
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Graphics, Fonts, and Color
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Simple Animation and Threads
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More Animation, Images, and Sound
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Managing Simple Events and Interactivity
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Creating User Interfaces with the awt
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Windows, Networking, and Other Tidbits
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Modifiers, Access Control, and Class Design
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Packages and Interfaces
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Exceptions
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Multithreading
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Streams and I/O
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Using Native Methods and Libraries
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Under the Hood
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Java Programming Tools
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Working with Data Structures in Java
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Advanced Animation and Media
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Fun with Image Filters
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Client/Server Networking in Java
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Emerging Technologies
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appendix A :- Language Summary
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appendix B :- Class Hierarchy Diagrams
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appendix C The Java Class Library
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appendix D Bytecodes Reference
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appendix E java.applet Package Reference
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appendix F java.awt Package Reference
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appendix G java.awt.image Package Reference
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appendix H java.awt.peer Package Reference
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appendix I java.io Package Reference
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appendix J java.lang Package Reference
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appendix K java.net Package Reference
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appendix L java.util Package Reference
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Troubleshooting
If you’ve run into any problems with the previous examples, this section can help. Here are some of the most common problems and how to fix them:
Bad command or filename or Command not found
These errors result when you do not have the JDK’s bin directory in your execution path, or the path to that directory is wrong. On Windows, double-check your autoexec.bat file; on UNIX, check the system
file with your path commands in it (.cshrc, .login, .profile, or some similar file).
javac: invalid argument
Make sure the name of the file you’re giving to the javac command is exactly the same name as the file. In particular, in the DOS shell you want to use the Windows filename with a .java extension, not the DOS
equivalent (HELLOW~1.jav, for example).
Warning: public class HelloWorldApplet must be defined in a file called HelloWorldApplet.java
This error most often happens if there is a mismatch between the name of the class as defined in the Java file itself (the name following the word class) and the name of the java source file. Both the filenames must
match, including upper- and lowercase letters (this particular error implies that the filename had lowercase letters). Rename either the filename or the class name, and this error will go away.
Insufficient-memory errors
The JDK is not the most efficient user of memory. If you’re getting errors about memory, consider closing larger programs before running Java compiles, turn on virtual memory, or install more RAM.
Other code errors
If you’re unable to compile the Java source files because of other errors I haven’t mentioned here, be sure that you’ve typed them in exactly as they appear, including all upper- and lowercase letters. Java is case
sensitive, meaning that upper- and lowercase letters are treated differently, so you will need to make sure that everything is capitalized correctly. If all else fails, try comparing your source files to the files on the
CD-ROM.
Certainly! Troubleshooting Java applets can involve various aspects, including code issues, browser compatibility, security settings, and more. Here are some common troubleshooting steps:
1. **Check Java Installation**: Ensure that the Java Runtime Environment (JRE) is installed on your system and that it’s up-to-date. You can check this by visiting the Java website and using their verification tool.
2. **Browser Compatibility**: Java applets are no longer supported in most modern web browsers due to security concerns. Make sure you’re using a browser that still supports Java applets, such as Internet Explorer 11 (on Windows) or Safari (on macOS).
3. **Java Security Settings**: Configure your Java security settings to allow Java applets to run. You can do this through the Java Control Panel, which is typically found in your system’s Control Panel or System Preferences.
4. **Check Applet Code**: Review your Java applet code for any errors or issues. Make sure that all necessary methods are properly implemented and that there are no syntax errors.
5. **Console Output**: Check the browser console for any error messages related to your Java applet. These messages can provide valuable insights into what might be going wrong.
6. **Applet Parameters**: If your applet takes parameters, ensure that they are being passed correctly from the HTML code to the Java applet.
7. **Security Restrictions**: Java applets are subject to strict security restrictions, and certain operations may be restricted or blocked altogether. Make sure your applet isn’t attempting any prohibited operations.
8. **Update Libraries**: If you’re using third-party libraries or frameworks in your applet, make sure they are up-to-date and compatible with the version of Java you’re using.
9. **Test on Different Systems**: Test your Java applet on different systems and browsers to identify any platform-specific issues.
10. **Consider Alternatives**: If you continue to encounter issues with Java applets, consider alternative technologies such as Java Web Start, which provides a way to deploy full-featured Java applications via the web without the limitations of applets.
By following these troubleshooting steps, you should be able to diagnose and resolve most issues with Java applets. If you encounter specific error messages or issues, feel free to provide more details, and I can offer more targeted assistance.
