String Builder Class

[Vishal Hegde]

what is the meaning of synchronized methods and
what does this sentence actualy mean-"StringBuilder class consists of mutable sequence of charecters"
and what does 'thread-safe' mean

[Jesper de Jong]

Have a look at Synchronization in Sun's Java tutorials.

A piece of code is thread-safe if it still works correctly when multiple threads execute it at the same time. (Click on the link, the Wikipedia article explains it in much more detail).

About "StringBuilder class consists of mutable sequence of charecters": Class StringBuilder contains a sequence of characters, which you can modify - unlike for example class String, which is immutable.

[Campbell Ritchie]

If you read the StringBuilder documentation, you find it has lots of methods called "delete" or "insert" or "append" with void return types. It allows you to alter the contents of "writing" and then turn it to a String with the toString() method.

[Rob Spoor]

Campbell Ritchie wrote:lots of methods called "delete" or "insert" or "append" with void return types.

Not void, StringBuilder. These methods return another reference to the StringBuilder object itself that allows you to chain methods. For example:

String s = new StringBuilder().append("Hello").append("World!").insert(5, ' ').delete(11, 12).toString(); // Hello World

[Campbell Ritchie]

Yes, Rob, I had forgotten about the return types. Sorry.