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java_introduction [2015/06/09 13:59] Joel Dare [Compiled] |
java_introduction [2020/06/01 22:53] |
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| - | ===== Java Introduction ===== | ||
| - | These are my notes for the Java programming language. I'm a professional programmer but I'm new to Java. I'm jotting down the fundamentals here as I learn them. | ||
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| - | ==== Hello World ==== | ||
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| - | An initial Java application looks like the following. | ||
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| - | <code> | ||
| - | public class Application { | ||
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| - | public static void main(String[] args) { | ||
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| - | System.out.println("Hello World"); | ||
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| - | } | ||
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| - | } | ||
| - | </code> | ||
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| - | ==== Compile to Bytecode ==== | ||
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| - | Java code starts as plain text files and then is compiled to bytecode. If the code above is in a file called Application.java then the following command compiles that. | ||
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| - | javac Application.java | ||
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| - | That creates an Application.class file. You can then run the application (Application.class) using: | ||
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| - | java Application | ||
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| - | ==== SQLite Library ==== | ||
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| - | You can download and use libraries as .jar files. You'll find the SQLite library on Bitbucket at the URL below. | ||
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| - | https://bitbucket.org/xerial/sqlite-jdbc/downloads | ||
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| - | Download the latest version and place it in the same directory as your application. | ||
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| - | Import the file into your application with the following line. In the Hello World example above this will be the first line in the Application.java file. | ||
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| - | import java.sql.*; | ||
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| - | After importing the file you will compile your application again. | ||
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| - | javac Application.java | ||
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| - | Then you need to execute your application with the library specified in the -classpath (or -cp) argument. The way you do this differs slightly between Unix like OS's and Windows. Here's how you do it on Unix like OS's. | ||
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| - | java -classpath ".:sqlite-jdbc-(VERSION).jar" Application | ||
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| - | Here's the Windows variation. | ||
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| - | java -classpath ".;sqlite-jdbc-(VERSION).jar" Application | ||
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| - | Make sure you replace (VERSION) with the actual version of the sqlite-jdbc library you downloaded into the current working directory. | ||
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| - | I believe the colon (:) and semi-colon (;) are separators while the dot (.) indicates the current directory. | ||