import java.io.File;
import java.io.FileNotFoundException;
import java.util.Scanner;


public class Equals {

	// where is the constructor?
	// what does that mean?
	
	public void testEqualsEquals (String a, String b) {
		System.out.println("Testing '" +a + "' == '" + b + "' is " +
				(a == b));
	}

	public void testDotEquals (String a, String b) {
		System.out.println("Testing '" +a + "' .equals() '" + b + "' is " +
				(a.equals(b)));
	}

	public void testTwo(String msg, String a, String b) {
		System.out.println("Testing: " + msg);
		testEqualsEquals(a, b);
		testDotEquals(a, b);
		System.out.println();
	}


	public void testEquals(){

		int Five1 = 5;
		int Five2 = 4+1;
		double doubleFive = 5.0;
		
		// primitives
		
		// no surprise:
		if (Five1==Five2)
			System.out.println("primitive comparison: " + Five1 +  "==" + Five2 +"\n");
		else
			System.out.println("primitive comparison: " + Five1 +  "!=" + Five2 +"\n");
		

        // surprised?		
		if (Five1==doubleFive)
			System.out.println("primitive comparison: " + Five1 +  "==" + doubleFive +"\n");
		else
			System.out.println("primitive comparison: " + Five1 +  "!=" + doubleFive +"\n");

		
		String h = "hello ";
		String w = "world"; 
		String hw1 = "hello world";
		String hw2 = h+w;

		testTwo("String literal concatenation", hw1, hw2);

		// Look at different result here, java has only one copy of literals
		String s3 = "string";
		String s4 = "string";
		testTwo("two identical String literals\nJava keeps only one copy of identical Strings", s3, s4);

		System.out.println("LESSON:\n\"==\" for Strings is non intuitive\n" +
				           "Better use \".equals\" !!");
	}
	/**
	 * @param args: two Strings
	 * @throws FileNotFoundException 
	 */
	public static void main(String[] args) throws FileNotFoundException {
		// goal of this code:  == vs .equals
		new Equals().testEquals();
	}
	
	

}