Java 9 High Performance

Why bother compressing strings?

Now you know a little bit about heap, let's look at the String class and how strings are represented on heap. If you dissect the heap of your application, you will notice that there are two objects, one is the Java language String object that references the second object char[] that actually handles the data. The char datatype is UTF-16 and hence takes up to 2 bytes. Let's look at the following example of how two different language strings look:

2 byte per char[]
Latin1 String : 1 byte per char[]

So you can see that Latin1 String only consumes 1 byte, and hence we are losing about 50% of the space here. There is an opportunity to represent it in a more dense form and improve the footprint, which will eventually ...