The Java compiler is a software tool that transforms human-readable Java code into bytecode that the Java Virtual Machine (JVM) can comprehend and execute. The JVM is in charge of running Java applications on many systems, which makes Java a platform-independent language.
To guarantee that the resulting bytecode is effective and mistake-free, the compiler does a number of operations such as syntax and semantic evaluation, code optimization, and error checking.
The Java compiler is a vital component of the Java development process because it enables programmers to create code in a high-level language while still receiving the performance benefits of a compiled language.
Working of the Java Compiler
There are numerous essential steps involved in the process of authoring, compiling, running, and distributing Java code while utilizing a Java code editor. Let’s look at how these stages function in more detail:
- Writing the Java Code: The first step is to write the Java code in a code editor. Code editors provide features such as syntax highlighting, code completion, and debugging tools that make it simpler to write code.
- Saving the Code: After writing the code, it must be saved to a file with the.java extension. This file includes the program’s source code and will be used by the compiler to create bytecode.
- Compiling the Code: The next step is to use the Java compiler to build the Java code. This is usually done by using the javac command from the command line or by utilizing the code editor’s built-in compiler. The compiler reads the source code from the.java file, analyses it for grammar and semantics, optimizes it, and creates a bytecode that can be run on the JVM.
- Running the Program: Once the code has been compiled, it may be run using the Java command from the command line or by utilizing the code editor’s built-in interpreter. This will launch the JVM and load the bytecode created by the compiler, allowing the program to run.
- Debugging the Program: If there are any defects or difficulties with the program, they may be debugged using a variety of tools provided by the code editor or the JVM. These tools allow developers to walk through the code line by line, analyze variables, and identify issues that may be causing the program to behave incorrectly.
- Sharing the Code: After the code has been created, produced, and tested, it may be shared with others in a number of ways. As an illustration, the code can be created on a platform that hosts code, like GitHub, where other programmers can make modifications and additions to the code. The source code may additionally be distributed by emailing it to others or posting it to a public code source.
Example:
import java.util.Scanner;
public class Greeting {
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
System.out.print(“Please enter your name: “);
String name = scanner.nextLine();
System.out.println(“Hello, ” + name + “! Nice to meet you.”);
}
}
Output:
Please enter your name: Intellipaat
Hello, Intellipaat! Nice to meet you.
Loops in Java
‘for’ loop
The ‘for’ loop is used to execute a piece of code several times. It is divided into three sections: initialization, condition, and increment/decrement.
For Instance:
for (int i = 0; i < 5; i++) {
System.out.print(i + " ");
}
Output:
0 1 2 3 4
‘while’ loop
The ‘while’ loop is used to constantly run a piece of code as long as a given condition is true. Before running the block of code, it verifies the condition.
Here’s an illustration:
int i = 0;
while (i < 5) {
System.out.print(i + " ");
i++;
}
Output:
0 1 2 3 4
‘do-while’ loop
The ‘do-while’ loop is almost similar to the while loop in that it always runs the code block at least once before verifying the condition.
Here’s an instance:
int i = 0;
do {
System.out.print(i + " ");
i++;
} while (i < 5);
Output:
0 1 2 3 4
‘foreach’ loop
The ‘foreach’ loop iterates across an array or collection. It doesn’t use an index variable but instead iterates across the array or collection elements.
Following is an example:
int[] arr = {1, 2, 3, 4, 5};
for (int i : arr) {
System.out.print(i + " ");
}
Output:
1 2 3 4 5
Conditional Statements
‘if-else’ statement
The ‘if-else’ statement is used to run code based on a condition. If the condition is met, the code contained inside the ‘if’ block is run; otherwise, the code contained within the ‘else’ block is executed.
Here’s an instance:
int x = 5;
if (x > 9) {
System.out.println("x is greater than 9");
} else {
System.out.println("x is less than or equal to 9");
}
Output:
x is less than or equal to 9
‘switch’ statement
The ‘switch’ statement is used to run a block of code based on a number of different circumstances. It analyses an expression and compares it to various scenarios before running the code block associated with the corresponding case. If none of the conditions are met, the default block is run.
For instance:
int dayOfWeek = 2;
switch (dayOfWeek) {
case 1:
System.out.println("Monday");
break;
case 2:
System.out.println("Tuesday");
break;
case 3:
System.out.println("Wednesday");
break;
default:
System.out.println("Invalid day");
break;
}
Output:
Tuesday
Functions in Java
A function is a piece of code that does a specified goal. A function is referred to as a method in Java. To define a method, you describe its name, any parameters it accepts, and the code to be performed.
Example:
public class Main {
public static void main(String[] args) {
int result = addNumbers(5, 7);
System.out.println("The sum of the numbers is: " + result);
}
public static int addNumbers(int a, int b) {
int sum = a + b;
return sum;
}
}
Output:
The sum of the numbers is: 12
Syntax for Functions in Java
access_modifier return_type function_name(parameter_list) {
// code block
return return_value;
}
Where,
- access_modifier: Specifies the access level of the function. It can be a public, private, protected, or no-access modifier.
- return_type: Specifies the type of the value that the function returns. It can be any valid Java data type or void if the function does not return any value.
- function_name: Specifies the name of the function.
- parameter_list: Specifies the list of parameters that the function accepts. Each parameter is defined by its data type and name.
- code block: Specifies the statements that are executed when the function is called.
- return_value: Specifies the value that the function returns. The data type of the return value must match the return_type specified in the function declaration.
Understanding a Simple Java Code
public class Intellipaat{
public static void main(String[] args) {
System.out.println("Hello, Intellipaatians!");
}
}
Output:
Hello, Intellipaatians!
In this program, we have defined a class named ‘Intellipaat’ that contains a single method named main. This method is the entry point of the program, and it is executed when we run the program.
The main method calls the println method of the System.out object to print the message “Hello, Intellipaatians!” to the console. The println method adds a newline character at the end of the message, so the next output will start on a new line.
How to compile and run a Java program online?
Here are the steps required to compile and run Java programs online:
- Go to the java editor above and simply run your code.
- If there are no syntax errors in your code, the compiler will run the code seamlessly.
Additional Resources