done until 5.

bin/.gitignore

@@ -0,0 +1,2 @@
+/Spreadsheet.class
+/SpreadsheetTest.class

src/Spreadsheet.java

@@ -1,18 +1,35 @@
+import java.util.HashMap;
 
 public class Spreadsheet {
-
+
+	private HashMap<String, String> hm = new HashMap<String, String>();
+
 	public String get(String cell) {
-		// to be implemented
-		return null;
+		return hm.get(cell);
 	}
 
 	public void set(String cell, String value) {
-		// to be implemented
+		hm.put(cell, value);
 	}
 
 	public String evaluate(String cell) {
-		// to be implemented
-		return null;
+
+		String value = hm.get(cell);
+		String first = value.substring(0,1);
+		String last = value.substring(value.length() - 1);
+
+		if(isNumeric(value)){
+			return value;
+		}else if(first.equals("'") && last.equals("'")){
+			return value.substring(1, value.length()-1);
+		}else{
+			return "#Error";
+		}	
+	}
+
+	public static boolean isNumeric(String str)
+	{
+	  return str.matches("-?\\d+(\\.\\d+)?");  //match a number with optional '-' and decimal.
 	}
 
 }

tests/SpreadsheetTest.java

@@ -6,10 +6,62 @@
 
 public class SpreadsheetTest {
 
+
 	@Test
-	public void test() {
-		fail("Not yet implemented");
+	public void test_CreateSpreadsheet(){
 
+		Spreadsheet sheet = new Spreadsheet();
+
+		assertNotNull(sheet);
+
+	}
+
+	@Test
+	public void testGetter() {
+		Spreadsheet sheet = new Spreadsheet();
+		sheet.set("A1", "15");
+
+		assertTrue(sheet.get("A1") == "15");
+	}
+
+	@Test
+	public void testNegativeNumber() {
+		Spreadsheet sheet = new Spreadsheet();
+		sheet.set("A2", "-15");
+
+		assertTrue(sheet.evaluate("A2") == "-15");
+	}
+	@Test
+	public void testNonNumeric(){
+		Spreadsheet sheet = new Spreadsheet();
+		sheet.set("A3", "A5");
+
+		assertTrue(sheet.evaluate("A3") == "#Error");
+	}
+
+	@Test
+	public void testString(){
+		Spreadsheet sheet = new Spreadsheet();
+		sheet.set("A1", "'a string'");
+
+		assertEquals("a string",sheet.evaluate("A1"));
+	}
+
+	@Test
+	public void testUnquotedString(){
+		Spreadsheet sheet = new Spreadsheet();
+		sheet.set("A1", "a string");
+
+		assertEquals("#Error", sheet.evaluate("A1"));
+	}
+
+	@Test
+	public void testFormulas(){
+		Spreadsheet sheet = new Spreadsheet();
+		sheet.set("A1", "='a string'");
+
+		assertEquals("a string", sheet.evaluate("A1"));
 	}
 
 }
+