Help with HashMap!!!

Question

Hi all,
My program reads the data from the external file called: "long.txt" which consists of a million records...
The file is loaded into a list called: "HashMap list" and also store the keys into a separate array. Search is done in HashMap for all the key in the array or also known as an exhaustive search.
I have the files: "long.txt", "HashMapTestnew.java" and "MyData.java" in the same directory called: "tmp"...
Everything looks okay but when I try to compile this, I get the following error...
HashMapTestnew.java:38: cannot resolve symbol
symbol : class MyData
location: class MyData.HashMapTestnew
MyData md = new MyData( sKey, Integer.parseInt(sVal) );
^
HashMapTestnew.java:38: cannot resolve symbol
symbol : class MyData
location: class MyData.HashMapTestnew
MyData md = new MyData( sKey, Integer.parseInt(sVal) );
^
HashMapTestnew.java:55: cannot resolve symbol
symbol : class MyData
location: class MyData.HashMapTestnew
MyData md;
^
HashMapTestnew.java:66: cannot resolve symbol
symbol : class MyData
location: class MyData.HashMapTestnew
md = (MyData) me.getValue();
^
4 errors
Tool completed with exit code 1
import java.util.*;
import java.io.*;
public class HashMapTestnew
public static HashMap getMapList()
     String MyData;
     Int sKey;
String strLine;
HashMap hm = new HashMap();
try
BufferedReader fBR = new BufferedReader( new FileReader("long.txt") );
while ( fBR.ready() )
strLine = fBR.readLine();
if (strLine != null)
StringTokenizer st = new StringTokenizer(strLine, "\t");
String sKey = st.nextToken();
String sVal = st.nextToken();
MyData md = new MyData( sKey, Integer.parseInt(sVal) );
hm.put(sKey, md);
fBR.close();
catch (IOException ioe)
System.out.println("I/O Trouble ...");
return hm;
public static void showMapList(HashMap hashMap, int n)
String strVal;
String strNdx;
MyData md;
System.out.println("\nHashMap List (first 10 records):");
Map.Entry me;
Set shm = hashMap.entrySet();
Iterator j = shm.iterator();
int i = 0;
while (j.hasNext() && (i++)< n)
me = (Map.Entry) j.next();
strVal = (String) me.getKey();
md = (MyData) me.getValue();
System.out.println(i + ": " + md.getVal() + "\t" + md.getNdx() );
public static String[] getKeys(HashMap hashMap)
String[] key = new String[hashMap.size()];
Map.Entry me;
Set shm = hashMap.entrySet();
Iterator j = shm.iterator();
int i = 0;
while (j.hasNext())
me = (Map.Entry) j.next();
key[i] = (String) me.getKey();
i++;
return key;
public static void searchMapList(HashMap hashMap, String[] key)
int i,n=0;
System.out.println("Search Started:");
long tim1 = System.currentTimeMillis();
for (i=0; i<key.length; i++)
if (hashMap.containsKey(key))
n++;
long tim2 = System.currentTimeMillis();
System.out.println("Search Ended After " + (tim2-tim1) + " miliseconds.");
System.out.println("Searched for " + key.length + " keys.");
System.out.println("Found " + n + " keys.");
public static void main(String[] arg)
HashMap hashMap = getMapList(); // Create the hash map list
showMapList(hashMap, 10); // Display part of the hash map list
String[] searchKey = getKeys(hashMap); // an array of all search keys
searchMapList(hashMap, searchKey); // Search for all existing keys in the list
Can anybody help me with this?
I'm new to Java... What does the error message: "cannot resolve symbol
symbol : class MyData" mean???
P.S. When I compiled the file "MyData.java", it compiles without any error...
Thanks,
Lilian

Answer 1

I moved the 3 files ("MyData.java", "long txt" and "HashMapTest.java") to a directory called "MyData" as well as added the code: "package MyData;"
before the codes:
import java.util.*;
import java.io.*;
just to see if it would make any difference but I still got the following error messages:
C:\WINDOWS\DESKTOP\MyData\HashMapTest.java:38: cannot resolve symbol
symbol : class MyData
location: class MyData.HashMapTest
MyData md = new MyData( sKey, Integer.parseInt(sVal) );
^
C:\WINDOWS\DESKTOP\MyData\HashMapTest.java:38: cannot resolve symbol
symbol : class MyData
location: class MyData.HashMapTest
MyData md = new MyData( sKey, Integer.parseInt(sVal) );
^
C:\WINDOWS\DESKTOP\MyData\HashMapTest.java:55: cannot resolve symbol
symbol : class MyData
location: class MyData.HashMapTest
MyData md;
^
C:\WINDOWS\DESKTOP\MyData\HashMapTest.java:66: cannot resolve symbol
symbol : class MyData
location: class MyData.HashMapTest
md = (MyData) me.getValue();
^
4 errors
Tool completed with exit code 1
By the way, I'm compiling the java program using a Textpad editor and selecting Tools -->> Compile Java...
Let me know if you have any questions...
Thanks,
Lilian
location: class MyData.HashMapTestnewThis says that you have declared your HashMapTestnew
class to be in package MyData.
I have the files: "long.txt", "HashMapTestnew.java"and "MyData.java" in the same directory called:
"tmp"...
If you want HashMapTestnew to be in package MyData,
then it should have been in a directory called MyData.
But having a class with the same name as a package is
very confusing, so I don't think you should do that.
In fact, since you are new to Java I don't think you
u should use packages at all until you can compile
non-packaged classes correctly.
I'm surprised I don't see the line "package MyData" at
the top of the code you posted. But then I'm not
surprised, because since your class isn't in the right
directory for that package, you should have got
different error messages. What exactly did you type
at the command line to compile the class?