Using bufferedreader to insert into a vector

Question

I am trying to read from a text file in an incremental fashion back into a form. I have tried it only reading the first record off the textfile and it works great; however, I run into problems when I try to read the entire file into a Vector or Array. Code is as follows:
Vector vLine = new vLine(10,1);
String tCardFile = new String("timecard.txt");
File file = new File(tCardFile);
BufferedReader br = new BufferedReader(new FileReader(file));
String lineRead = null;
lineRead = new String();
while((lineRead = br.readLine()) !=null){ vLine.addElement(lineRead);}When I compile, I get this funky error that reads:
Note: D:\javafiles\TimeCard.java uses unchecked or unsafe operations.
Note: Recompile with -Xlint:unchecked for details.Now, I have taken the vector back out and tried using an array with 100 elements and I no longer get the above error but I run into two issues:
First...the "timecard.txt" fill is meant to keep growing so I need a dynamic array like the vector class
Second...I get a null value as being entered in either the array or the vector.
Any thoughts ?

Answer 1

you going to get the same compiler warning about "unchecked or unsafe operations"...
the reason is because the compiler is not able to guarantee the type safety of your raw ( non-generified ) vector/arraylist operations...
i.e.
Vector v = new Vector(); // raw vector
String s = "a string";
Integer i = new Integer(1);
v.add(s); // able to add arbitrary types like a String
v.add(i); // or an Integer
String k = (String) v.element(1); // class cast exceptionto fix this, you use generics... then the compiler will ensure that only the data type that the vector is declared to accept via generics will be allowed
Vector<String> v = new Vector<String>(); // raw vector
String s = "a string";
Integer i = new Integer(1);
v.add(s); // works because v is a Vector of Strings
v.add(i); // will not work because a Vector of String cannot accept Integer objects
String k = v.element(1); // no cast necessary because the Vector on handles Stringsit's the same with an ArrayList...
ArrayList<String> al = new ArrayList<String>();
have fun...
- MaxxDmg...
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