Java – NoClassDefFoundError: javax/swing/GroupLayout$Group on Mac Computer

Instead of hunting the root cause in the dark, I think it's better to explain how and why NPE's are caused and how they can be avoided, so that the OP can apply the newly gained knowledge to hunt his/her own trivial problem.

Look, object references (the variables) can contain either a fullworthy Object or simply nothing, which is null.

SomeObject someObject1 = new SomeObject(); // References something.
SomeObject someObject2 = null; // References nothing.

Now, if you're trying to access nothing (null), then you will undoubtely get a NullPointerException, simply because null doesn't have any variables or methods.

someObject1.doSomething(); // Works fine.
someObject2.doSomething(); // Throws NullPointerException.

Workarounding this is fairly simple. It can be done in basically two ways: either by instantiating it or just by ignoring it.

if (someObject2 == null) {
    someObject2 = new SomeObject();
}
someObject2.doSomething(); // No NPE anymore!

or

if (someObject2 != null) {
    someObject2.doSomething(); // No NPE anymore!
}

In case of a NPE, the first line number of the stacktrace points the exact line where the it is been caused. You told literally "line 272 is admin.birthList.add(list1);". This line contains two places where object references are been accessed/invoked (using the dot . operator). The first being admin.birthList and the second being birthList.add(list1). It's up to you to find out if one or both caused the NPE. If it is the first invocation, then admin is simply null. If it is the second invocation, then birthList is simply null. You can fix it by instantiating it with a fullworthy object.

Edit: If you have a hard time in determining the root cause (as turns out from comments), then you need to learn debugging. Run a debugger or just do "poor man's debugging" with help of a System.out.println() of every variable before accessing/invoking them. First look at line where the NPE is caused. If this is for example

admin.birthList.add(list1);

then you need to change it as follows to nail down the root cause:

System.out.println("admin: " + admin);
List<Birth> birthList = admin.birthList;
System.out.println("birthList: " + birthList);
birthList.add(list1);

check if any of them prints null. Alternatively you can also do:

if (admin == null) throw new NullPointerException("admin is null!");
List<Birth> birthList = admin.birthList;
if (birthList == null) throw new NullPointerException("birthList is null!");
birthList.add(list1);

you can also separate the individual invocations over separate lines so that you have enough to the line number to know which reference is null.

List<Birth> birthList = admin.birthList; // If NPE line points here, then admin is null.
birthList.add(list1); // If NPE line points here, then birthList is null.

EDIT: You still haven't indicated which is line 197 in the question, but I'll assume it's

p1 = conn.prepareStatement(s1);

This is almost certainly due to this bit of the constructor:

Connection conn=DriverManager.getConnection("jdbc:odbc:reg","system","suganthi");

This declares a local variable called conn. Presumably you also have an instance variable called conn, but the local variable is hiding it. You're assigning to the local variable, which means the instance variable is going to keep its default value of null. You probably meant just:

conn = DriverManager.getConnection("jdbc:odbc:reg","system","suganthi");

However, if an exception occurs you shouldn't just print "Error" and keep going... you should probably throw an exception from the constructor instead. After all, the instance isn't going to behave properly unless you've got a database connection.

You should also consider only creating a database connection when you actually need it, and closing it immediately afterwards. Use a connection pool to allow this to be efficient where appropriate.

Original answer

You haven't shown the bit of code which is throwing the exception - namely jButton1ActionPerformed, with line 197 being the culprit. You've shown us jButton3ActionPerformed instead.

Show us the right piece of code, with line numbers, and we're more likely to have a chance to help you. Or just look at what's being used on line 197 - something there is resulting in a null reference which you're trying to dereference, e.g.

int foo = someNullValue.getIntValue();

It may be the result of a method call though, e.g.

foo().getIntValue(); // Will throw if `foo()` returns null

As an aside, doing database work in the UI thread isn't generally a good idea - although as you're a beginner it may be simpler to get that right and live with the UI hanging during database access than getting multithreading right. You should consider threading it properly at a later date though, when you have more experience.