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Java Basic

1. What is the difference between interpretation and compilation? Is Java a compiled or interpreted language?​

Interpretation​

  • How it works: Code is translated and executed line by line
  • Translation and Execution happen simultaneously
  • Examples of languages: Python, JavaScript

Compilation​

  • How it works: The entire code is translated into machine code (binary) before execution.
  • Examples of compiled languages: C, C++

Is Java Compiled or Interpreted?​

  • Java is both compiled and interpreted

  • Java Execution Process

    • Compilation Phase:
      • Java source code (.java files) is compiled by the Java compiler (javac) into bytecode (.class files).
      • Bytecode is a platform-independent intermediate format.
    • Interpretation/Execution Phase:
      • The Java Virtual Machine (JVM) interprets the bytecode and translates it into machine code.
      • The JVM uses Just-In-Time (JIT) compilation to optimize frequently used bytecode by translating it into machine code for faster execution.

2. What is the difference in the use of the / symbol for floating-point and integer types?​

3. How is int converted to double, and is double converted to int rounded or truncated?​

  • int and double
System.out.println(10/3); // Output: 3 (int)
System.out.println(10/3.0); // Output: 3.3333333333333335 (double)
System.out.println((int)(10/3.0)); // Output: 3 (int)
  • Converting int to double
int myInt = 42
double myDouble = myInt;
System.out.println(myDouble); // Output: 42.0
  • Converting double to int
double myDouble = 42.99;
int myInt = (int) myDouble;  
System.out.println(myInt);  // Output: 42