Initial data commit

Task/Twos-complement/Java/twos-complement.java

@@ -0,0 +1,30 @@
+import java.util.List;
+
+public final class TwosComplement {
+
+	public static void main(String[] args) {
+		List<Integer> examples = List.of( 0, 1, -1, 42 );
+		
+		System.out.println(String.format("%9s%12s%24s%34s", "decimal", "hex", "binary", "two's complement"));
+		System.out.println(
+            String.format("%6s%12s%24s%32s", "-----------", "--------", "----------", "----------------"));
+		
+		for ( int example : examples ) {
+			System.out.println(
+                String.format("%5d%18s%36s%13d", example, toHex(example), toBinary(example), twosComplement(example)));
+		}
+	}
+	
+	private static String toHex(int number) {
+		return String.format("%8s", Integer.toHexString(number).toUpperCase()).replace(" ", "0");
+	}
+	
+	private static String toBinary(int number) {
+		return String.format("%32s", Integer.toBinaryString(number)).replace(" ", "0");
+	}
+	
+	private static int twosComplement(int number) {
+		return ~number + 1;
+	}
+
+}