Introduction to Java and JDK Setup

1import java.util.Arrays;
2
3/**
4 * EnvironmentInfo.java
5 * Verifies your Java setup and demonstrates basic program structure.
6 * Compile: javac EnvironmentInfo.java
7 * Run:     java EnvironmentInfo arg1 arg2
8 */
9public class EnvironmentInfo {
10
11    public static void main(String[] args) {
12        printHeader();
13        printJavaInfo();
14        printSystemInfo();
15        printCommandLineArgs(args);
16        printMemoryInfo();
17    }
18
19    private static void printHeader() {
20        System.out.println("======================================");
21        System.out.println("  Java Environment Verification Tool  ");
22        System.out.println("======================================");
23    }
24
25    private static void printJavaInfo() {
26        System.out.println("\n--- Java Version Info ---");
27        System.out.printf("Java Version    : %s%n",
28            System.getProperty("java.version"));
29        System.out.printf("Java Vendor     : %s%n",
30            System.getProperty("java.vendor"));
31        System.out.printf("JVM Name        : %s%n",
32            System.getProperty("java.vm.name"));
33        System.out.printf("Class Version   : %s%n",
34            System.getProperty("java.class.version"));
35        System.out.printf("JAVA_HOME       : %s%n",
36            System.getProperty("java.home"));
37    }
38
39    private static void printSystemInfo() {
40        System.out.println("\n--- System Info ---");
41        System.out.printf("OS Name         : %s%n",
42            System.getProperty("os.name"));
43        System.out.printf("OS Version      : %s%n",
44            System.getProperty("os.version"));
45        System.out.printf("OS Architecture : %s%n",
46            System.getProperty("os.arch"));
47        System.out.printf("User Name       : %s%n",
48            System.getProperty("user.name"));
49        System.out.printf("Working Dir     : %s%n",
50            System.getProperty("user.dir"));
51    }
52
53    private static void printCommandLineArgs(String[] args) {
54        System.out.println("\n--- Command-Line Arguments ---");
55        if (args.length == 0) {
56            System.out.println("No arguments provided.");
57            System.out.println("Try: java EnvironmentInfo hello world");
58        } else {
59            System.out.printf("Argument count  : %d%n", args.length);
60            System.out.printf("Arguments       : %s%n",
61                Arrays.toString(args));
62            for (int i = 0; i < args.length; i++) {
63                System.out.printf("  args[%d]       : %s%n", i, args[i]);
64            }
65        }
66    }
67
68    private static void printMemoryInfo() {
69        Runtime runtime = Runtime.getRuntime();
70        long maxMemory  = runtime.maxMemory()  / (1024 * 1024);
71        long totalMemory = runtime.totalMemory() / (1024 * 1024);
72        long freeMemory  = runtime.freeMemory()  / (1024 * 1024);
73
74        System.out.println("\n--- JVM Memory Info ---");
75        System.out.printf("Max Heap        : %d MB%n", maxMemory);
76        System.out.printf("Total Heap      : %d MB%n", totalMemory);
77        System.out.printf("Free Heap       : %d MB%n", freeMemory);
78        System.out.printf("Used Heap       : %d MB%n", totalMemory - freeMemory);
79
80        System.out.println("\n======================================");
81        System.out.println("  Setup verified successfully!");
82        System.out.println("======================================");
83    }
84}