Day-06: Hello-world from JAVA

To install Java in Linux machine:
sudo apt install default-jdk -y

Code working flow:

1. Source Code to Byte Code – Compilation
2. Byte Code to Binary Code – Execution

Source Code to Byte Code – Compile Time

Compiler: A compiler turns your source code into byte code. This is an intermediate form that the computer can understand, but it's not ready to run directly.
Tools: IDE - IntelliJ or Eclipse, and the compiler - javac
Compiler: A compiler turns your source code into byte code. This is an intermediate form that the computer can understand, but it's not ready to run directly.

Tools: IDE - IntelliJ or Eclipse, and the compiler - javac
Compiler: A compiler turns your source code into byte code. This is an intermediate form that the computer can understand, but it's not ready to run directly.

Tools: IDE - IntelliJ or Eclipse, and the compiler - javac

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Byte Code to Binary Code – Run Time

What happens: After you have the byte code, it still needs to be turned into machine code that your computer's processor can execute.
JRE: The Java Runtime Environment (JRE), or similar, takes the byte code and turns it into binary machine code.
Tools: The JVM (Java Virtual Machine) reads the byte code and makes the program run by converting it into binary.
What happens: After you have the byte code, it still needs to be turned into machine code that your computer's processor can execute.

JRE: The Java Runtime Environment (JRE), or similar, takes the byte code and turns it into binary machine code.

Tools: The JVM (Java Virtual Machine) reads the byte code and makes the program run by converting it into binary.
What happens: After you have the byte code, it still needs to be turned into machine code that your computer's processor can execute.

JRE: The Java Runtime Environment (JRE), or similar, takes the byte code and turns it into binary machine code.

Tools: The JVM (Java Virtual Machine) reads the byte code and makes the program run by converting it into binary.

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Compile Time:
Source code → Byte code (done by the compiler).
Run Time:
Byte code → Binary code (done by the JRE/JVM).

Sample Java Programme:

public class First
{
 public static void main(String[] args)
    {
    System.out.println("Welcome To Java"); 
    }
}
public class First
{
 public static void main(String[] args)
    {
    System.out.println("Welcome To Java"); 
    }
}
public class First
{
 public static void main(String[] args)
    {
    System.out.println("Welcome To Java"); 
    }
}

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To Compilation this Source Code:
javac First.java

To Run this byte code:
java First

Output will be:

Some of the Common Errors:

 public class First {  
    public static void main(String[] args)  {     
        System.out.println("Welcome To Java");      
    } 
 public class First {  
    public static void main(String[] args)  {     
        System.out.println("Welcome To Java");      
    } 
 public class First {  
    public static void main(String[] args)  {     
        System.out.println("Welcome To Java");      
    } 

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Removed ‘}’ at the end

First.java:6: error: reached end of file while parsing } ^ 1 error

原文链接：Day-06: Hello-world from JAVA