Even though Java is projected as the most demanded language of the times, but has its own disadvantages. Of course, they are very minor in nature and need not be considered as drawbacks compared to the advantages it brings forward.
Following is the list of Java Drawbacks
a) Slow performance: The first and foremost drawback everyone accepts is Java's slow speed of execution. Of course it is designed so to get the affect of platform-independent feature. Designers do trying to increase the performance in other aspects like the introduction of JIT (Just-In-Time) compiler.
b) No support for low-level programming: With Java, low-level programming cannot be done as it is intended to be portable across platforms.
c) Poor features in GUI: Java supports GUI controls but with less features. For example, an image cannot be placed on a button. The is overcome with the introduction of javax.swing package. Swing controls come with abundant features that are comparable with any GUI available.
d) No control over garbage collection: Garbage collection is one of the built-in features of Java and is entirely managed by JVM. programmer is not given any handles to control the garbage collection to make coding simple. For this reason, Java does not come with delete(), free(), malloc() and sizeof() etc. functions.
What Java Can't Do?
Even though Java is termed as a production language where productivity is very high, but still it cannot do certain things. The productivity is possible due to the abundant classes available in Java API that can cater to the very specific needs of the programmer. Java includes a few thousands of classes with JDK 1.5 that takes care of many minute aspects of coding. Even though it is hyped so heavily, but it cannot be used to develop low-level programming. Using Java, a new OS or new protocols or DVD burning software etc. cannot be programmed.