If anybody asks this query throughout interview, then your reply must be each i.e. Java is each compiled and interpreted programming language. Java code is written in .java recordsdata (also called the supply file), which is compiled by javac, a Java compiler into class recordsdata.
Not like C or C++ compiler, Java compiler would not generate native code. These class recordsdata comprise byte-code, which is totally different than machine or native code. Java digital machine or JVM interprets byte codes in the course of the execution of the Java program.
So, you possibly can see it is each compiled and interpreted language, however this reply is incomplete till you point out JIT (Simply in time compiler) which does one other spherical of compilation to provide native code, which might immediately be executed by the corresponding platform.
We are going to study how JIT works within the subsequent part.
Java is each Compiled and Interpreted Language however how?
The above reply is totally appropriate however it’s not full. What javac (Java compiler, which comes alongside JDK) does is a pseudo compilation, it would not convert Java supply code into native code, which might immediately be executed by CPU, actual compilation into native code is completed by one other program referred to as Simply in Time compiler, also called JIT. That is really an optimization achieved on JVM by Java platform engineers.
When JVM interprets Java byte code, it additionally gathers helpful statistics, like which a part of code is sizzling and at all times run. As soon as JVM has sufficient information to make such a choice, JIT can compile that a part of code e.g. technique or block into native code.
This native code will then immediately be executed by a machine, with out decoding by JVM. JIT offers an immense efficiency enhance to Java purposes and that is another reason why Java can also be used to jot down high-performance purposes like digital buying and selling methods, algorithmic gateways and so on, together with native languages like C and C++.
In brief, Java is each compiled and interpreted language. It compiles utilizing javac and JIT and interprets utilizing Java digital machine. Right here is the sequence of issues usually occurs from writing to execution of a Java program :
1) Programmer write supply code and retailer that right into a .java file. At all times bear in mind the title of your Java supply file should be the identical as the general public class declared inside that file, for instance, if there’s a public class referred to as Order contained in the Java file, then it title should be Order.java.
2) javac compiles .java fie and creates class recordsdata, which comprise byte code. This byte code is major purpose of Java being platform-independent.
3) JVM executes these class recordsdata and gathers statistics of execution run. These statics are used to find out sizzling spot i.e. a part of your code which executes 90% of the time.
4) After a sure threshold, when JVM has sufficient information to decide, JIT compiles ceaselessly used byte codes into native code, which is then immediately executed by the platform. This offers a efficiency enhance to Java purposes.
