still work to do...

src/Spreadsheet.java

@@ -1,18 +1,77 @@
+import java.util.HashMap;
 
 public class Spreadsheet {
+	public static final String ERR_STR="#Error";
+
+	HashMap<String, String> sheet = new HashMap<String, String>();
 
 	public String get(String cell) {
 		// to be implemented
-		return null;
+		return sheet.get(cell);
 	}
 
 	public void set(String cell, String value) {
+		sheet.put(cell, value);
 		// to be implemented
 	}
 
 	public String evaluate(String cell) {
 		// to be implemented
-		return null;
+		String val = sheet.get(cell);
+		String retval =ERR_STR;
+
+		retval=strip_quote(val);
+		if (retval==ERR_STR)
+			return ERR_STR;
+
+		if (retval.startsWith("="))
+		{
+			retval=strip_quote(val.substring(1, val.length()));
+			if (retval==ERR_STR)
+				return ERR_STR;
+			else 
+				if (retval.length()>2)
+					return retval;
+				try{
+				retval=sheet.get(val.substring(1));
+				}
+			catch (Exception e) {
+
+				retval=ERR_STR;
+
+				// TODO: handle exception
+			}
+
+		}	
+
+		if (val.startsWith("-") || val.startsWith("+"))
+			retval=val;
+		else
+			retval=ERR_STR;
+
+		return (retval);
+
 	}
 
+	public String strip_quote(String str)
+	{
+		String retval=str;
+		if (retval.startsWith("\""))
+		{
+			retval=retval.substring(1);
+
+			if (retval.endsWith("\""))
+			{
+				retval=retval.substring(0, retval.length()-1);
+			}
+			else
+				retval=ERR_STR;
+		}
+		/*
+		else
+			if (!str.matches("-?\\d+(\\.\\d+)?"))
+				retval=ERR_STR;
+				*/
+		return retval;
+	}
 }

tests/SpreadsheetTest.java

@@ -4,12 +4,96 @@
 import org.junit.Test;
 
 
+
 public class SpreadsheetTest {
+	public static final String ERR_STR="#Error";
 
-	@Test
+/*	@Test
 	public void test() {
 		fail("Not yet implemented");
 
 	}
+*/
+	Spreadsheet sp= new Spreadsheet();
+
+	@Test
+	public void test_SetA1_1_Get()
+	{
+		sp.set("A1", "1");
+
+		assertEquals("1",sp.get("A1"));
+
+	}
+
+	@Test
+	public void test_SetA2_minus1_Evaluate()
+	{
+		sp.set("A2", "-1");
+
+		assertEquals("-1",sp.evaluate("A2"));
+
+	}
+
+	@Test
+	public void test_SetA2_5A_Evaluate()
+	{
+
+		sp.set("A2", "5A");
+
+		assertEquals(ERR_STR,sp.evaluate("A2"));
+
+	}
+
+	@Test
+	public void test_A1_quoted_string()
+	{
+		sp.set("A1", "\"a string\"");
+		assertEquals("a string",sp.evaluate("A1"));
+	}
+
+	@Test
+	public void test_A1_Invalid_quoted_string()
+	{
+		sp.set("A1", "\"a string");
+		assertEquals(ERR_STR,sp.evaluate("A1"));
+	}
+
+	@Test
+	public void test_A1_evaluate_formula_quoted_string()
+	{
+		sp.set("A1", "=\"a string\"");
+		assertEquals("a string",sp.evaluate("A1"));
+	}
+
+	@Test
+	public void test_A1_evaluate_formula_invalid_quoted_string()
+	{
+		sp.set("A1", "=\"a string");
+		assertEquals(ERR_STR,sp.evaluate("A1"));
+
+	}
+
+
+	@Test
+	public void test_SetA2_formula_Refernce_A5_Evaluate()
+	{
+
+		sp.set("A2", "=A5");
+		sp.set("A5", "5");
+
+		assertEquals("5",sp.evaluate("A2"));
+
+	}
+	@Test
+
+	public void test_SetA2_formula_5A_Evaluate()
+	{
+
+		sp.set("A2", "=5A");
+
+		assertEquals(ERR_STR,sp.evaluate("A2"));
+
+	}
+
 
 }