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 */
package javacheatsheet;
/**
 *
 * @author Charles
 */
import java.io.*;
public class JavaCheatSheet {

    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {
        int input=0;
        System.out.println("Hello");
        try {
            input = Integer.parseInt(args[0]);
        } catch (ArrayIndexOutOfBoundsException e) {
            System.out.println("Expected one integer argument.."+e.getMessage());
        } catch (NumberFormatException e) {
            System.out.println("Expected an integer argument.."+e.getMessage());
        } catch (Exception e) {
            // in general, catching ALL exceptions in a function in this
            // fashion is a bad idea.  can you guess why?
            System.out.println("Unexpected error\n"+e.getMessage());
        } finally {
            System.out.println("Input: "+input);
        }
    
        // on GL, 170! can be computed, but 171! yields infinity
        double result = factorial(input);      // Compute the factorial
        System.out.println(result);            // Print out the result
        fileDemo();
        System.out.println("Java supports Unicode, hence characters are 16 bits");
        System.out.println("Even Greek letters such as \u03be");
        statementDemo();
        iterableDemo();
    }
    
    public static void iterableDemo() {
        int[] firstFewPrimes = new int[] {2,3,5,7,11,13,17,19};
        for (int p: firstFewPrimes) System.out.println(p);
    }
    
    public static double factorial(int x) {  // This method computes x!
        if (x < 0)                             // Check for bad input
            return 0.0;                          // If bad, return 0
        double fact = 1.0;                     // Begin with an initial value
        while(x > 1) {                         // Loop until x equals 1
            fact = fact * x;                     // Multiply by x each time
            x = x - 1;                           // And then decrement x
        }                                      // Jump back to start of loop
        return fact;                           // Return the result
    }                                        // factorial() ends here

    public static void fileDemo() {
        assert ((1 == 1) == true);  // the other Boolean is false
        System.out.println("show off opening" + " and closing of files");
        assert("any old string" instanceof String);
        Object obj = new int[] {1,2,3};
        assert obj instanceof int[] && obj instanceof Object;
        String thisFile = 
                "C:/Users/Charles/Documents/NetBeansProjects/"+
                "JavaCheatSheet/src/javacheatsheet/JavaCheatSheet.java";
        // try with resources!  like foreach, new to Java since 1995 :-)
        try (BufferedReader in = 
            new BufferedReader(new FileReader(thisFile))) {
            String line;
            int count=0;
            // count the characters in this file
            while ( (line = in.readLine()) != null) {
                count += line.length();
            }
            System.out.println("File "+thisFile+" is of length "+count);
        } catch (IOException e) {
            System.out.println("Cannot find myself");
        }
    }
    
    public static void statementDemo() {
        int i = 0;
        i++;    // expressions can be used as statements, for side-effects
        int j;
        for (j=10; j>0; j--) {
            System.out.print(" "+j);
        }
        System.out.println("\nBlastoff!");
    
    }
}