Algorithm Test

[Anemone]

Hey!

I have a problem with an algortim I have to Find the Longrest
comnon substring between two strings

that should return a matrix if you have let say

"abcs" and "sac"

"" "" "" ""
"" "" "a" "a"
"" "" "a" "a"
"" "" "a" "ac"
"" "s" "s" "ac"

public class Find {

public static String find(String str1, String str2)
{
int i, j;
int m = str1.length();
int n = str2.length();

String[][] b = new String [m][n];

for (int s = 1; s<m; s++)
b[s][0] = "";
for (int z = 1; z<n; z++)
b[0][z] = "";

for (i = 1; i<m; i++)
for(j = 1; j<n; j++)
{
if(str1.charAt(i-1) == str1.charAt(j-1))
b[i][j] = b[i-1][j-1]+str1.charAt(+1);
else if(b[i-1][j].length() >= b[i][j-1].length())
b[i][j]= b [i-1][j];
else
  b[i][j] = b[i][j-1];
}
return b [m-1][n-1]
}
}

I think the algoritm is right but I need
help so I can test if it actually work.

[Anemone]

}
return matrix [m-1][n-1]

}

public static void main(String [] args)
{
String str1 = "abbbccwwdw";
String str2 = "abbcddwdwd";
System.out.println(lcs(str1,str2));
}
}

getting the result "nullbbbbbb"
what is it that is wrong?