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How to use TextPad to run an application

Go to all tips in Murachs Java SE6 book

How to use TextPad to run an application

Once you've compiled the source code for an application, you can run that application by pressing Ctrl+2. In this figure, the application prints text to theconsole. As a result, TextPad starts a console window like the one shown in this figure. Then, you can usually press any key to end the application and close the window. Sometimes, however, you may need to click on the Close button in the upper right corner of the window to close it.

The Tools menu


A compile-time error

Text printed to the console

How to compile and run an application

  • To compile the current source code, press Ctrl+1 or select Tools Compile Java.
  • To run the current application, press Ctrl+2 or select Tools Run Java Application.
  • If you encounter compile-time errors, TextPad will print them to a window named Command Results.
  • To switch between the Command Results window and the source code window, press Ctrl+F6, press Ctrl+Tab, or double-click on the window that you want in the Document Selector pane that's on the left side of the TextPad window.
  • When you print to the console, a DOS window like the one above is displayed. To close the window, press any key or click the Close button in the upper right corner.

Introduction to Java ...................................................................... 4
Toolkits and platforms ....................................................................... 4
Java compared to C++ ...................................................................... 4
Java compared to C# ........................................................................ 4
Applications, applets, and servlets ....................................................... 6
How Java compiles and interprets code ................................................ 8
How to prepare your system for using Java .................................. 10
How to install the JDK ..........................................................................10
A summary of the directories and files of the JDK ...................................12
How to set the command path ...............................................................14
How to set the class path ..................................................................... 16
How to use TextPad to work with Java ........................................... 18
How to install TextPad ......................................................................... 18
How to use TextPad to save and edit source code ................................... 20
How to use TextPad to compile source code ........................................... 22
How to use TextPad to run an application ............................................... 22
Common error messages and solutions ................................................. 24
How to use the command prompt to work with Java ...................... 26
How to compile source code ................................................................. 26
How to run an application ..................................................................... 26
How to compile source code with a switch .............................................. 28
Essential DOS skills for working with Java ............................................. 30
How to use the documentation for the Java SE API ....................... 32
How to install the API documentation ..................................................... 32
How to navigate the API documentation ................................................. 34
Introduction to Java IDEs ................................................................ 36
The Eclipse IDE for Java ....................................................................... 36
The NetBeans IDE ................................................................................ 38
The BlueJ IDE ...................................................................................... 38
Perspective ....................................................................................... 40

The chapter 1 of Murach's Java SE 6 excellent book (it is a MUST for all newbees!) is published on our site with written permission of the copyright owner. It was slightly adapted to our site layout. If you want to take a look at PDF version please follow the link here.

7879 bytes more | comments? | Printer Friendly Page  Send to a Friend | Score: 0
Posted by jalex on Friday, August 17, 2007 (21:37:44) (5156 reads)

Common error messages and solutions

Go to all tips in Murachs Java SE6 book

Common error messages and solutions

Figure 1-11 summarizes some common error messages that you may encounter when you try to compile or run a Java application. The first two errors illustrate compile-time errors. These are errors that occur when the Java compiler attempts to compile the program. In contrast, the third error illustrates a runtime error. That is an error that occurs when the Java interpreter attempts to run the program but can't do it.

The first error message in this figure involves a syntax error. When the compiler encounters a syntax error, it prints two lines for each error. The first line prints the name of the .java file, followed by a colon, the line number for the error, another colon, and a brief description of the error. The second line prints the code that caused the error, including a caret character that tries to identify the location where the syntax error occurred. In this example, the caret points to the right brace, but the problem is that the previous line didn't end with a semicolon.


The second error message in this figure involves a problem defining the public class for the file. The compiler displays an error message like this when the file name for the .java file doesn't match the name of the public class defined in the source code. For example, the TextApp.java file must contain this code

public class TestApp{

If the name of the file doesn't match the name of the public class (including capitalization), the compiler will give you an error like the one shown in this figure. You'll learn more about the syntax for defining a public class in the next chapter.

The third error message in this figure occurs if you try to run an application that doesn't have a main method. You'll learn how to code a main method in the next chapter. For now, just realize that every application must contain a main method. To correct the error shown in this figure, then, you must add a main method to the class or run another class that has a main method.

Most of the time, the information displayed by an error message will give you an idea of how to fix the problem. Sometimes, though, the compiler gets confused and doesn't give you accurate error messages. In that case, you'll need to double-check all of your code. You'll learn more about debugging error messages like these as you progress through this book.

A common compile-time error message and solution

Error:C:\java\examples\ch01\TestApp.java:6: ';' expected
          }
          ^

Description: The first line in this error message displays the file name of the .java file, a number indicating the line where the error occurred, and a brief description of the error. The second line displays the line of code that may have caused the error with a caret symbol (^) below the location where there may be improper syntax.

Solution: Edit the source code to correct the problem and compile again.

Another common compile-time error message and solution

Error: C:\java\examples\ch01\TestApp.java:1: class testapp is
           public, should be declared in a file named testapp.java
           public class testapp
           ^

Description: The .java file name doesn't match the name of the public class. You must save the file with the same name as the name that's coded after the words"public class". In addition, you must add the java extension to the file name.

Solution: Edit the class name so it matches the file name (including capitalization), or change the file name so it matches the class name. Then, compile again.

A common runtime error message and solution

Error: Exception in thread "main" java.lang.NoSuchMethodError:
          main

Description: The class doesn't contain a main method.

Solution: Run a different class that does have a main method, or enter a main method for the current class.

Description

  • When you compile an application that has some statements that aren't coded correctly, the compiler cancels the compilation and displays messages that describe the compiletime errors. Then, you can fix the causes of these errors and compile again.
  • When the application compiles without errors (a "clean compile") and you run the application, a runtime error occurs when the Java Virtual Machine can't execute a compiled statement. Then, the application is cancelled and an error message is displayed.

Introduction to Java ...................................................................... 4
Toolkits and platforms ....................................................................... 4
Java compared to C++ ...................................................................... 4
Java compared to C# ........................................................................ 4
Applications, applets, and servlets ....................................................... 6
How Java compiles and interprets code ................................................ 8
How to prepare your system for using Java .................................. 10
How to install the JDK ..........................................................................10
A summary of the directories and files of the JDK ...................................12
How to set the command path ...............................................................14
How to set the class path ..................................................................... 16
How to use TextPad to work with Java ........................................... 18
How to install TextPad ......................................................................... 18
How to use TextPad to save and edit source code ................................... 20
How to use TextPad to compile source code ........................................... 22
How to use TextPad to run an application ............................................... 22
Common error messages and solutions ................................................. 24
How to use the command prompt to work with Java ...................... 26
How to compile source code ................................................................. 26
How to run an application ..................................................................... 26
How to compile source code with a switch .............................................. 28
Essential DOS skills for working with Java ............................................. 30
How to use the documentation for the Java SE API ....................... 32
How to install the API documentation ..................................................... 32
How to navigate the API documentation ................................................. 34
Introduction to Java IDEs ................................................................ 36
The Eclipse IDE for Java ....................................................................... 36
The NetBeans IDE ................................................................................ 38
The BlueJ IDE ...................................................................................... 38
Perspective ....................................................................................... 40

The chapter 1 of Murach's Java SE 6 excellent book (it is a MUST for all newbees!) is published on our site with written permission of the copyright owner. It was slightly adapted to our site layout. If you want to take a look at PDF version please follow the link here.

10836 bytes more | comments? | Printer Friendly Page  Send to a Friend | Score: 0
Posted by jalex on Friday, August 17, 2007 (21:35:36) (5839 reads)

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