Let’s try to understand how garbage collection works in Java:
Garbage collection is mainly the process of marking or identifying the unreachable objects and deleting them to free the memory. The implementation lives in the JVM, the only requirement is that it should meet the JVM specifications. These are the different types of garbage collectors in Java:
- Serial Garbage Collector
- Parallel/Throughput Garbage Collector
- CMS Collector
- G1 Collector
Let’s take a look at a few advantages of garbage collection in Java:
- It automatically deletes the unused objects that are unreachable to free up the memory
- Garbage collection makes Java memory efficient
- It need not be explicitly called since the implementation lives in the JVM
- Garbage collection has become an important and standard component of many programming languages
Let’s try to understand why Destructors are not used in Java.
Garbage collection is mainly the process of marking or identifying the unreachable objects and deleting them to free the memory. The implementation lives in the JVM, the only requirement is that it should meet the JVM specifications. These are the different types of garbage collectors in Java:
- Serial Garbage Collector
- Parallel/Throughput Garbage Collector
- CMS Collector
- G1 Collector
Let’s take a look at a few advantages of garbage collection in Java:
- It automatically deletes the unused objects that are unreachable to free up the memory
- Garbage collection makes Java memory efficient
- It need not be explicitly called since the implementation lives in the JVM
- Garbage collection has become an important and standard component of many programming languages
Let’s try to understand why Destructors are not used in Java.
August 25, 2020
August 25, 2020
Java Finalize() Method
It becomes fairly difficult for any developer to force the execution of a garbage collector, but there is an alternative to this. We can use the object.finalize() method which works exactly like a destructor in Java.
An Object.finalize() method is inherited in all Java objects. It is not a destructor but is used to make sure or provide additional security to ensure the use of external resources like closing the file, etc before the program shuts down. You can call it by using the method itself or system.runFinalizersOnExit(true).
The use of finalize() method is highly not recommended since it can be very unsafe and in some cases used incorrectly.
Let’s take a simple example to show how finalize() can be used to call the garbage collector.
It becomes fairly difficult for any developer to force the execution of a garbage collector, but there is an alternative to this. We can use the object.finalize() method which works exactly like a destructor in Java.
An Object.finalize() method is inherited in all Java objects. It is not a destructor but is used to make sure or provide additional security to ensure the use of external resources like closing the file, etc before the program shuts down. You can call it by using the method itself or system.runFinalizersOnExit(true).
The use of finalize() method is highly not recommended since it can be very unsafe and in some cases used incorrectly.
Let’s take a simple example to show how finalize() can be used to call the garbage collector.
August 25, 2020
August 25, 2020
What is the right data type to represent a price in Java?
Anonymous Poll
26%
int
10%
decimal
18%
Bigdecimal
29%
double
17%
float
August 26, 2020
August 26, 2020
public class MyClass {
{
public static void main(String[] args) { {for (int i = 5; i > 0; i--) { System.out.print(i); } } }}
{
public static void main(String[] args) { {for (int i = 5; i > 0; i--) { System.out.print(i); } } }}
Anonymous Poll
12%
1 2 3 4 5
12%
0 1 2 3 4
69%
5 4 3 2 1
7%
4 3 2 1 0
August 26, 2020
August 27, 2020
class Check
{
public static void main(String args[]) { int num = 9; if ( num % 2 == 0 ) System.out.println("output1"); else System.out.println("output2"); } }
{
public static void main(String args[]) { int num = 9; if ( num % 2 == 0 ) System.out.println("output1"); else System.out.println("output2"); } }
Anonymous Quiz
31%
output1
69%
output2
August 28, 2020
What is a Method?
A method is basically a set of code which is referred to by name and can be called or invoked at any point in a program, just by utilizing the method’s name. Each method is given its own name. When that name is in a program, the execution branches to the body of that method. Suppose the method is completed, control returns to the area of the code from which it was called, and the program continues on to the next line of code.
A method is basically a set of code which is referred to by name and can be called or invoked at any point in a program, just by utilizing the method’s name. Each method is given its own name. When that name is in a program, the execution branches to the body of that method. Suppose the method is completed, control returns to the area of the code from which it was called, and the program continues on to the next line of code.
September 14, 2020
September 14, 2020
Methods are basically referred to time savers, which means that they allow you to have the repetition of sections of code without having to retype the code. In addition to this, methods can also be saved and utilized again and again in a freshly developed program. These methods are used to perform certain actions, and they are also called as functions.
Different types of methods in Java
Talking about the different types of methods used, there are two types, which are:
- Standard Library Methods
- User-defined Methods
Let’s understand them in detail.
Standard library methods
The Standard library methods are built-in methods in Java that are readily available for use. These standard libraries come along with the Java Class Library that is present in a Java archive (*.jar) file with JVM and JRE.
How to use the standard libraries?
The file stdlib.jar holds together all standard libraries into one single file. To access these libraries, you must add stdlib.jar to your Java classpath. There are several ways to do so. Here are the two ways through which you can do:
Use the javac-introcs and java-introcs commands. javac-introcs and java-introcs commands are accessible with the command line (for OS X or Linux) or Git Bash (for Windows).
% javac-introcs MyProject.java
% java-introcs MyProject
Use IntelliJ project folders. If you use IntelliJ, the project folders are preconfigured to include stdlib.jar in the classpath.
Some examples of Standard libraries are:
print(): This method comes under java.io.PrintSteam which helps in printing the string that is written within the quotation.
sqrt(): This is a method of Math class that returns the square root of that specific number.
How to create a method?
A method must be declared within a specific class. It is defined with the name of the method, followed by parentheses “()”. Java provides some pre-defined methods, such as System.out.println() and many more.
Different types of methods in Java
Talking about the different types of methods used, there are two types, which are:
- Standard Library Methods
- User-defined Methods
Let’s understand them in detail.
Standard library methods
The Standard library methods are built-in methods in Java that are readily available for use. These standard libraries come along with the Java Class Library that is present in a Java archive (*.jar) file with JVM and JRE.
How to use the standard libraries?
The file stdlib.jar holds together all standard libraries into one single file. To access these libraries, you must add stdlib.jar to your Java classpath. There are several ways to do so. Here are the two ways through which you can do:
Use the javac-introcs and java-introcs commands. javac-introcs and java-introcs commands are accessible with the command line (for OS X or Linux) or Git Bash (for Windows).
% javac-introcs MyProject.java
% java-introcs MyProject
Use IntelliJ project folders. If you use IntelliJ, the project folders are preconfigured to include stdlib.jar in the classpath.
Some examples of Standard libraries are:
print(): This method comes under java.io.PrintSteam which helps in printing the string that is written within the quotation.
sqrt(): This is a method of Math class that returns the square root of that specific number.
How to create a method?
A method must be declared within a specific class. It is defined with the name of the method, followed by parentheses “()”. Java provides some pre-defined methods, such as System.out.println() and many more.
September 14, 2020
September 14, 2020
And the method definition consists of a method header and a method body.
Now, Let’s understand how to create a user-defined Method in Java?
How to create a user-defined method in Java?
Syntax:
Now, Let’s understand how to create a user-defined Method in Java?
How to create a user-defined method in Java?
Syntax:
September 14, 2020
September 14, 2020
Here, a method named myMethod() is defined.
You can see three access modifiers – public, static and void before the function name.
1 The public keyword makes myMethod() method public. Public members can be accessed from outside of the class. To learn more, visit: Access modifiers in Java
2 The static keyword denotes that the method can be accessed without creating the object of the class.
3 The void keyword signifies that the method doesn’t return any value.
You can see three access modifiers – public, static and void before the function name.
1 The public keyword makes myMethod() method public. Public members can be accessed from outside of the class. To learn more, visit: Access modifiers in Java
2 The static keyword denotes that the method can be accessed without creating the object of the class.
3 The void keyword signifies that the method doesn’t return any value.
September 14, 2020
How to call a method/ method calling?
To call a method in Java, you have to write the method’s name followed by parentheses () and a semicolon ;
For using a method in a program, it should be called. There are two ways in which a method is called i.e., the method returns a value or it returns nothing.
The process of method calling is simple. When a program invokes a method, the program control automatically gets transferred to the called method. This called method returns control to the caller in these two conditions, they are namely:
- When the return statement is executed.
- When the control reaches the method ending closing brace.
To call a method in Java, you have to write the method’s name followed by parentheses () and a semicolon ;
For using a method in a program, it should be called. There are two ways in which a method is called i.e., the method returns a value or it returns nothing.
The process of method calling is simple. When a program invokes a method, the program control automatically gets transferred to the called method. This called method returns control to the caller in these two conditions, they are namely:
- When the return statement is executed.
- When the control reaches the method ending closing brace.
September 14, 2020
September 14, 2020
In this case,
1 When Java is executing the program code, it encounters the method in the code.
2 The execution then branches to the myFunction() method and executes code inside the body of the method.
3 After the execution of the code inside the method body is completed, the program returns to the original state and executes the next statement.
Let’s see a Java method in action by defining a Java class.
1 When Java is executing the program code, it encounters the method in the code.
2 The execution then branches to the myFunction() method and executes code inside the body of the method.
3 After the execution of the code inside the method body is completed, the program returns to the original state and executes the next statement.
Let’s see a Java method in action by defining a Java class.
September 14, 2020
September 14, 2020