Java API to find out the JDK version a class file is compiled for

Java API to find out the JDK version a class file is compiled for

import java.io.*; 
 public class ClassVersionChecker { 
 public static void main(String[] args) throws IOException { 
     for (int i = 0; i < args.length; i++) 
         checkClassVersion(args[i]); 
 } 
  
     private static void checkClassVersion(String filename) 
         throws IOException 
     { 
         DataInputStream in = new DataInputStream 
          (new FileInputStream(filename)); 
  
         int magic = in.readInt(); 
         if(magic != 0xcafebabe) { 
           System.out.println(filename + " is not a valid class!");; 
         } 
         int minor = in.readUnsignedShort(); 
         int major = in.readUnsignedShort(); 
         System.out.println(filename + ": " + major + " . " + minor); 
         in.close(); 
     } 
 } 
 

The possible values are :

major  minor Java platform version  
 45       3           1.0 
 45       3           1.1 
 46       0           1.2 
 47       0           1.3 
 48       0           1.4 
 49       0           1.5 
 50       0           1.6