Java Tutorial

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Java Loops

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Java Programs

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Java Sorting

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Java OOPs Concepts

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Java Strings

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Java Exceptions

Exception Handling in Java Java try catch Java throw Java throws Difference between throw and throws Java finally Java Custom Exception Java Exception Propagation

Garbage Collection

Automatic Resource Management in Java Java Garbage Collection Java finalize() Java gc() Difference between final, finally and finalize

Multithreading

Multithreading in Java Process and Thread in Java Basic Terms in Multithreading Java Thread creation Thread Scheduler in Java Java Thread class DeadLock in Java

Java IO

Java IO Java Read File Java BufferedWriter Java InputStreamReader Java File Java Read File Line By Line Java FileOutputStream Jar File in Java

Serialization

Java Serialization Java transient

Networking

Java Network Programming Java Socket Programming Java URL Java URLConnection HttpURLConnection in Java Java InetAddress Java DatagramSocket and Java DatagramPacket

AWT

Java AWT

Swing

Swing in Java

Java Collections

Collections in Java Java List Interface ArrayList in Java LinkedList in Java Vector in Java Stack in Java ArrayList vs LinkedList in Java ArrayList vs Vector in Java Java Set Interface HashSet in Java LinkedHashSet in Java TreeSet in Java Java Queue Interface PriorityQueue in Java ArrayDeque in Java Java Map Interface HashMap in Java LinkedHashMap in Java TreeMap in Java Dictionary in Java Hashtable in Java Properties in Java Collections class in Java Java Comparable Java Comparator Comparable vs Comparator in Java

Java Generics

Generics in Java

Java Annotations

Annotations in Java

Java JDBC

Java JDBC Tutorial

Java Differences

Java vs JavaScript Python vs Java Kotlin vs Java Java vs C++ C# vs Java Static vs Non-static in Java C vs Java int vs Integer in Java Stack vs Heap in Java Java Array vs ArrayList

How to

How to run Java program How to set path in Java How to check the Java version in cmd How to install Java in Windows 10 How to run Java program in cmd How to call a method in Java How to sort an array in Java How to iterate HashMap in Java How to write Java program How to create an array in Java How to create a package in Java How to generate random numbers in Java How to input String in Java How to create thread in Java How to find length of String in Java How to sort a string in Java How to use scanner in Java How to achieve multiple inheritance in Java How to run Java program in Eclipse How to call a function in Java How to create array of objects in Java How to create custom exception in Java How to achieve abstraction in Java How to call static method in Java

Java 8 Features

Java 8 Features Lambda Expressions in Java Functional Interface in Java Streams in Java Java Base64 Encoding and Decoding Parallel Arrays Sort in Java

Java 9 Features

Java 9 Tutorial Java 9 Try With Resources Java 9 Interface Private Method

Java Servlet Tutorial

Java Servlets Tutorial

Java JSP Tutorial

Java JSP Tutorial

Hibernate Tutorial

Hibernate Tutorial

Spring Tutorial

Spring Tutorial

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Spring MVC Tutorial

Jenkins Tutorial

Jenkins Tutorial

Java Math Methods

Math.abs() Math.acos() Math.addExact() Math.asin() Math.atan () Math.atan2() Math.cbrt() Math.ceil() Math.copysign() Math.cos() Math.cosh() Math.decrementExact() Math.exp() Math.expm1() Math.floor() Math.floorDiv() Math.floorMod() Math.getExponent() Math.hypot() Math.IEEEremainder() Math.incrementExact() Math.log() Math.log10() Math.log1p() Math.max() Math.min() Math.multiplyExact() Math.multiplyFull() Math.negateExact() Math.nextAfter() Math.nextDown() Math.nextUp() Math.pow() Math.random() Math.rint() Math.round() Math.scalb() Math.signum() Math.sin() Math.sinh() Math.sqrt() Math.subtractExact() Math.tan() Math.tanh() Math.toDegrees() Math.toIntExact() Math.toRadians() Math.ulp()

Java String Methods

toCharArray() copyValueOf() endsWith() equals() equalsIgnoreCase() format() getBytes() getChars() hashCode() indexOf() intern() isEmpty() join() lastIndexOf() length() replace() replaceAll() replaceFirst() split() startsWith() subSequence() substring() toLowerCase() toUpperCase() trim() valueOf()

Java Conversion

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Misc

Functional Interfaces in Java Singleton class in Java Awesome explanation of Strings in Java Object class in Java Static class in Java All the important string methods in Java String Handling Method in Java What are Array strings in Java Advantages and Disadvantages of Strings in Java Big Decimal class in Java Class definition in Java Char and String differences in Java Difference between String, StringBuffer and StringBuilder in java Replace character in string Java String Coding Interview Questions in Java What is String in Java? String isnullorempty in Java String Matches in Java Trim Method in String Java Bean class in Java Libraries in Java Arithmetic Operations on String in Java Convert Char array to string in java Check whether Java is installed or not How to calculate time difference in Java How to stop execution after a certain time in Java Jagged Array in Java Java ArraylistRemove() Time Complexity Java Swing Time Picker Zigzag Array in Java

Java finally

Java finally: There are some statements in a program whose execution is extremely important. For example, closing of a database connection. Statements that do the closing of the database connection must be put inside the Java finally block. The Java finally block ensures that whatever statements are present in the finally block must be executed irrespective of the exception raised in the program or not. The Java finally can be used with the try-catch or can be used only with the try keyword.

Java finally syntax

The syntax of the finallykeyword is mentioned below.

 try
 {
     // Statements that are potent to cause an exception
 }
 catch
 {
    // for Handling the raised exception
 }
 finally
 {
    // Statements that have to be executed irrespective of an exception raised or not
 }
 We can also use finally without using catch.
 try
 {
     // Statements that are potent to cause an exception
 }
 finally
 {
    // Statements that have to be executed irrespective of an exception raised or not
 } 

Java finally Keyword Example

Let’s try to understand the usage of the keyword finally with the help of some examples.

FileName: FinallyExample.java

 public class FinallyExample
 {
 // main method
 public static void main(String argvs[])
 {
 try
 {
 // an int array of 9 elements
 int arr[] = new int[9];
 arr[10] = 90; // raises ArrayIndexOutOfBoundsException
 System.out.println(arr);  // this statement never gets executed
 } 
 catch(ArrayIndexOutOfBoundsException e)
 {
 System.out.println("The used index is out of range." + e);
 } 
 finally
 {
 System.out.println("This print statement has to be executed.");
 } 
 System.out.println("Finally, out of the try - catch - finally block"); 
 }  
 } 

Output:

 The used index is out of range.java.lang.ArrayIndexOutOfBoundsException: Index 10 out of bounds for length 9
 This print statement has to be executed.
 Finally, out of the try - catch – finally block 

Explanation:The try-catch block handles the ArrayIndexOutOfBoundsException. After the try-catch block, the control shiftsto the finally block. Now observe the following example.

FileName: FinallyExample1.java

 public class FinallyExample1
 {
 // main method
 public static void main(String argvs[])
 {
 try
 {
 int x = 7 / 0; // raises ArithmeticException
 System.out.println(x);  // this statement never gets executed
 } 
 finally
 {
 System.out.println("This print statement has to be executed.");
 } 
     // the last print statements
 System.out.println("Finally, out of the try - finally block"); 
 }  
 } 

Output:

 This print statement has to be executed.
 Exception in thread "main" java.lang.ArithmeticException: / by zero
                at FinallyExample1.main(FinallyExample1.java:9) 

Explanation:In this program, we see that the ArithmeticException is raised in the try block. Even though the raised exception is not handled by the program, the finally block executes. It shows the importance of the finally block.  Any sensitive piece of code that has to be executedhas to be put only in the finally block. Notice the last print statement is not executed. It is because the raised exception is not handled, and that leads to the abnormal termination of the program.

Non-Execution of the Finally Block

Even though finally block ensures that some statements have to be executed, no matter what happens. However, there are some scenarioswhere even the finally block does not execute. The following program illustrates the same.

FileName: FinallyExample2.java

 public class FinallyExample2
 {
 // main method
 public static void main(String argvs[])
 {
 try
 {
 System.out.println("Inside the Java try block.");
 System.exit(0); // nothing executes after the execution of this statement
 }
 catch (Exception e)
 {
 System.out.println("Inside the Java catch block" + e);
 }
 finally
 {
 System.out.println("Inside the Java finally block");
 }
 System.out.println("Finally, out of the try - catch - finally block");
 }  
 } 

Output:

Inside the Java try block.

Explanation: In this program, we observe thatfinally block is not executed. Because of the statement System.exit(0);.The System.exit(0); statement stops the program by forcefully terminating the JVM (Java Virtual Machine). Hence, the finally block does notexecute.

Remember:

1) The finally block cannot exist independently. It has to come either with a try block or with a try-catch block.

2) The finally block always executes after the try block.

3) Presence of a catch block does not guarantee that the finally block executes after the catch block or not. The following program illustrates the same.

FileName: FinallyExample3.java

Output:

 Inside the Java try block.
 Inside the Java finally block.
 Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: Index 3 out of bounds for length 3
                at FinallyExample3.main(FinallyExample3.java:16) 

Explanation: In this program, we see the finally block is executed, and the catch block is not executed. The reason behind it is the type of exception raised in the program. The catch block is expecting the ArithmeticException to be raised in the try block. However, the try block raises the ArrayIndexOutOfBoundsException. Thus, there is a mismatch between what is expected and what is present. As the raised exception is not handled, the last print statemen also does not get executed, and the program terminates abnormally. In this example, we see that after the try block, the finally block gets executed, even though the catch block is present. Now, observe the following program.

FileName: FinallyExample4.java

 public class FinallyExample4
 {
 // main method
 public static void main(String argvs[])
 {
 // try - catch - finally    
 try
 {
 System.out.println("Inside the Java try block.");
    // creating an array of three elements
    int arr[] = new int[3];
 arr[3] = 5; // raises ArrayIndexOutOfBoundsException
 }
 catch (ArrayIndexOutOfBoundsException ae)
 {
 System.out.println("Inside the Java catch block \n " + ae);
 }
 finally
 {
 System.out.println("Inside the Java finally block.");
 }
 // the last print statement
 System.out.println("Finally, out of the try - catch - finally block.");
 }  
 } 

Output:

 Inside the Java try block.
 Inside the Java catch block
 java.lang.ArrayIndexOutOfBoundsException: Index 3 out of bounds for length 3
 Inside the Java finally block.
 Finally, out of the try - catch - finally block. 

Explanation: In this program, we see the finally block is executed after the catch block. It is because the raised exception is getting handled in the catch block.

4) The finally block does not guarantee that an exception cannot be raised in its block.

5) If the raised exception inside the finally block is not handled, the program terminates abnormally.

6) One can use try-catch inside the finally block to handle the raised exception inside the finally block. Observe the following program.

FileName: FinallyExample5.java

 public class FinallyExample5
 {
 // main method
 public static void main(String argvs[])
 {
 // try - catch - finally    
 try
 {
 System.out.println("Inside the Java try block.");
    String str = null;
 str.equals("tutorial & example");
 }
 catch (NullPointerException ne)
 {
 System.out.println("Inside the Java catch block " + ne);
 }
 finally
 {
 System.out.println("Inside the Java finally block.");
    // try-catch block inside the finally block
    try
    {
        // raising the ArithmeticException
        // inside the finally block
        int x = 78 / 0;
    }
 catch(ArithmeticException ae)
    {
 System.out.println("Handling exception successfully in the catch block. " + ae);
    }
 }
 // the last print statement
 System.out.println("Finally, out of the try - catch - finally block.");
 }  
 } 

Output:

 Inside the Java try block.
 Inside the Java catch block java.lang.NullPointerException
 Inside the Java finally block.
 Handling exception successfully in the catch block. java.lang.ArithmeticException: / by zero
 Finally, out of the try - catch - finally block. 

Explanation: The above program shows an exception can be raised as well as handled in the finally block.



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