(i) JDK installation and environment variable configuration
1. JDK Download
http://www.oracle.com/technetwork/java/javase/downloads/ index.html, download the SE Standard Enterprise version, has been updated to 1.8.X version, but the latest version does not support XP system, has been verified (unable to install on the XP system), so select version 1.7.
2. Environment variable Configuration
Configure path and classpath, My Computer, properties---Advanced environment variables, add the Java installation path to the user variable, add the bin path in path, and add the Lib path in the classpath. After configuration, you can enter the DOS test is configured intact. The commands are as follows: Java-version and Javac-version
(ii) Java programs
1, use Notepad to build a Test.java file, the contents are as follows:
Class example1_1{
public static void Main (String [] args) {
int A, B;
a=100;
System.out.println (a);
System.out.println ("hello,java!");
}
}2, compile, command as follows: Javac Test.java
After executing this command, a Example1_1.class file is generated in the current directory.
3, run, command as follows: Java example1_1
Note: The Java +[class name], if entered into Java Example1_1.class, will prompt the error "error: Cannot find or Load main class Example1_1.class"
(iii) Java applets
1, the preparation of Example1_2.java file, the contents are as follows:
Import Java.awt.*;import java.applet.*;
public class Example1_2 extends applet{
public void Paint (Graphics g) {
G.setcolor (Color.Blue);
g.DrawString ("Welcome You", 30,20);
G.setcolor (color.red);
g.DrawString ("No thing", 30,50);
}
}2, the preparation of example1_2.html file, the contents are as follows:
<title> First applet</title>
<body>
3. Compile Java file, javac Example1_2.java generate file Example1_2.class
<applet code= "Example1_2.class" width= "height=" >
</applet>
</body>4. Running Java applet: Appletviewer example1_2.html
In the beginning of Java, the Web is suggested to write with Notepad, and I still feel that with a good code editor is better, at least can be highlighted and aligned. More irritable often need to use DOS command to enter the working directory, can: run->cmd directly into the directory where the code is, in fact, it is OK: My Computer--right---management--Local Users and groups, user--- Adminstrator-> Double-click Profile, add working directory to local path.
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