Terminate code in java

Java how to terminate the program in java

Also make sure that you never catch Exception , if you are doing that then you are catching all the types of exceptions which you may not intend to handle also. For instance a library that calls when something bad happens is going to cause havoc for an application that uses it.

How to terminate a process in java?

Decide how much time you are willing to spend generating one file before skipping it. You can set a timer with that time limit and check if it’s still uploading the same file since the last time it went off. You shouldn’t notice that much of a difference in CPU performance with just one timer that performs a simple check.

fileTimer = new Timer(maxDelay, checkFile); fileTimer.start(); //set currentFile ActionListener checkFile = new ActionListener() < String lastFile; public void actionPerformed(ActionEvent e) < if (this.lastFile == currentFile) //terminate process else lastFile = currentFile >> 

I’m not quite sure how to terminate the process. I’m not super familiar with multi-threading. Any ideas on that @anshulkatta?

Which method is used to terminate the execution of, In C, C++ and Java the program terminates when the main/Main function/method returns. The difference is that in inJava the return type Main is void. On normal termination it always returns success. To indicate an abnormal termination and return a non-zero exit code, use System.exit.

What is the good practice to terminate program in catch clause

If this code is part of the application itself then calling System.exit(int) is possibly the best option. (But if the application is «failing», then you should call exit with a non-zero return code. Zero conventionally means «succeeded».)

However, if there is a significant possibility that this code is going to be embedded / reused in a larger Java application, calling System.exit(. ) is problematic. For instance a library that calls System.exit(. ) when something bad happens is going to cause havoc for an application that uses it.

For something like that, you might throw a custom runtime exception which you catch and handle specifically in your main method. (If I was doing that, I’d pass the Exception as a constructor parameter to the custom exception . and make it the cause exception. And I wouldn’t print it / log it at that point.)

(Calling System.exit(. ) also causes problems when you are unit testing . ‘cos the call will most likely pull the plug on the JVM running the test suite!)

The other point is that catch (Exception . ) is almost always a BAD IDEA. The point is that this catches just about everything (including all sorts of things that you never dreamed could happen!) and buries them. It is far better to catch the specific exceptions you are expecting (e.g. checked exceptions) and can deal with . and just let the rest propagate in the normal way.

If you are stuck with catch (Exception . ) because you are using something that is declared as throwing Exception , the best way to deal with it is to change the throws Exception . And the sooner the better. Change the throws Exception to declare a list of (more) specific exceptions that you expect to be thrown by the method.

public int callMyMethod() < try< myMethod(); >catch(Exception ex) < ex.printStackTrace(System.out); System.exit(0); // terminates with exit code 0, no extra stack trace. >> 

Exception handling is one of the most important aspects in programming. The answer for your question depends on what type of application you are working on.

system.exit(0) will just terminate your program and this can create a lot of havoc . Also make sure that you never catch Exception , if you are doing that then you are catching all the types of exceptions which you may not intend to handle also.

Always catch Specific exception such that it gives you opportunity to handle it in a manner which you need.

Performance — How to stop/terminate java program by, I want to terminate my current Java Program’s Execution as like, System.exit(0); while user press either one of following key-combination from key-board, 1. Ctrl+C 2. Ctrl+Alt+Del I have searched a lot but nothing seems to be correct. if possible then please provide me a fruitful code snippet too. thank you, 🙂

How to terminate Java program without closing a window

It’s difficult to say something without to see your application. But probably this piece of code will help you to understand how to implement what you want:

import java.awt.BorderLayout; import java.awt.FlowLayout; import java.awt.event.ActionEvent; import java.awt.event.ActionListener; import javax.swing.JButton; import javax.swing.JFrame; import javax.swing.JLabel; import javax.swing.JPanel; import javax.swing.SwingUtilities; import javax.swing.SwingWorker; import javax.swing.WindowConstants; public class SwingWorkerTest implements Runnable < private JButton cancelButton = new JButton("Cancel"); private JButton runButton = new JButton("Run"); private JLabel label = new JLabel("Press 'Run' to start"); private LongWorker longWorker; @Override public void run() < JFrame frm = new JFrame("Long task test"); frm.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE); cancelButton.addActionListener(new ActionListener() < @Override public void actionPerformed(ActionEvent e) < longWorker.terminate(); >>); runButton.addActionListener(new ActionListener() < @Override public void actionPerformed(ActionEvent e) < longWorker = new LongWorker(); runButton.setEnabled(false); cancelButton.setEnabled(true); label.setText("Task in progress. Press 'Cancel' to terminate."); longWorker.execute(); >>); JPanel bottomPanel = new JPanel(new FlowLayout(FlowLayout.TRAILING)); bottomPanel.add(runButton); bottomPanel.add(cancelButton); frm.add(label); frm.add(bottomPanel, BorderLayout.SOUTH); frm.setSize(400, 200); frm.setLocationRelativeTo(null); frm.setVisible(true); > public static void main(String[] args) < SwingUtilities.invokeLater(new SwingWorkerTest()); >private class LongWorker extends SwingWorker  < private volatile boolean terminated; @Override protected Void doInBackground() throws Exception < // check special variable tov determine whether this task still active for (int i = 0; i < 1000 && !terminated; i++) < readFile(); >return null; > @Override protected void done() < if (terminated) < label.setText("Process terminated. Press 'Run' to restart."); >else < label.setText("Process done. Press 'Run' to restart."); >cancelButton.setEnabled(false); runButton.setEnabled(true); > // dummy method - make 10 milliseconds sleep private void readFile() < try < Thread.sleep(10); >catch (InterruptedException ex) < // Nothing here >> public void terminate() < terminated = true; >> > 

Java — Best way to exit a program when I want an, 4 Answers. Sorted by: 46. If you let the exception propagate all the way up to the main () method, the program will end. There’s no need to call System.exit, just allow the exception to bubble up the stack naturally (by adding throws IOException) to the necessary methods. Edit: As @Brian pointed out, you …

How to terminate a java code in linux using

Usually pressing Ctrl+C will terminate the application.

You could also find the process ID for the process (use ps to see a list of running processes) and then kill the process using the kill command.

You have a few different options some of which have been covered. Since you aren’t at the machine in question you can’t use ctrl+c obviously.

You could manually identify the pid with ps (ps -ef|grep ) and then kill it with the aformentioned kill

but I prefer pkill if it is available on the system. The pkill command will search the process tree for what you specify and kill that. It is similall to the killall command however pkill is grepping the processes extended attributes where killall only works on the process names. In this case your process is java but you probably don’t want to kill all instances of java only the specific one so with pkill you can use the name of the jar file.

You can try using Ctrl-C or just close the terminal ..

How can I exit a Java program without, As long as you don’t need to return custom exit code (other than 0, as returned by System.exit (0)) and don’t start new threads, you can terminate your program by doing. in your main () method. Note that there is no value returned, so that you don’t need to change your main () method from void to int. If you wrote your program …

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Different ways to terminate program in Java

Generally, Java programs terminate when they reach the end of the program, but there may be times when we need to know how to terminate a program when a certain condition is met or an exception occurs.

1. Ways To Terminate Program in Java
2. The exit() Method
3. Return Statement
4. The Halt Method

Let us get started with Different ways to terminate program in Java.

Ways To Terminate Program in Java

Terminating a program means to stop the execution of the program and more specifically, kill the process that was executing the program. This can be done from the terminal executing the program but can also be done from within the Java code.

Different ways to terminate program in Java are:

1. Using exit() Method
2. Return Keyword
3. Halting the JVM itself using the Halt Method

The exit() Method

The System class contains several useful class fields and methods.Among the facilities provided by the System class are standard input, standard output, and error output streams; access to externally defined properties and environment variables; a means of loading files and libraries; and a utility method for quickly copying a portion of an array.One such important method provided by System class is exit().This method terminates the currently running Java Virtual Machine.It takes a status code as a parameter.This method doesn’t return any value. Exit can be disabled by the SecurityManager class.

Status values can be used to denote the outcome of the Program

• 0 is used when execution went fine.
• Any other integer value when some error has occurred. Different values can denote different kinds of Errors.

import java.util.*; class Example < public static void main(String[] args) < System.out.println("Hello , You've reached the first print statement"); System.exit(0); System.out.println("Second Println here"); >> 

Hello , You've reached the first print statement 

from the above example we can see that after the exit() method is called , JVM will terminate , the lines beyond this call are not executed.
The System.exit() call internally invokes the Runtime.getRuntime().exit(0).

Return Statement

Return statement is usually used to return a value from a function incase the function returns any value , else it is used to terminate a function if it returns void.Return would cause a program to exit , if it’s present inside the main method of a class. If you add more code after return, the compiler will complain about unreachable code.

class Example < public static void Main(String[] args) < if(args.length < 2) < System.out.println("Expecting more arguments"); return; >for(String s : args) < System.out.println(s); >> > 

from the above program, we can clearly see that return can be used to exit a program only if it’s used inside the main method. What happens if we put some code after return? Let’s see.

when we try to execute this program , we’ll get the following error.

Demo.java:6:error: unreachable statement System.out.println(“Cannot print this or even exeute”); ^ 1 error 

Thus , Return is only viable as a way to exit when it’s inside the Main method.

The Halt Method

Every Java application has a single instance of class Runtime that allows the application to interface with the environment in which the application is running.
This class has various methods to interact with the environment in which the Java virtual Machine is Running. Few uses of this class include:

• Used to get Current Runtime.
• Can be used to find the Free memory in Java Virtual Machine.
• Exit the running Java Virtual Machine by initiating the Shutdown Sequence.
• Can be used to forcibly terminate the currently running Java Virtual Machine.

It is the halt method of this Runtime class that we’re interested in. When you call the exit method , the Shutdown sequence is started , Shutdown Hooks or Exit finalizers are called. These Hooks are pieces of code to be executed when the JVM is shutting down. The Halt method forcibly terminates the JVM , hence no hooks are called. Halt method should be used with extreme caution as it abruptly terminates the JVM. Halt is rarely used . Halt can be disabled by the SecurityManager class.

Runtime.getRuntime().halt(int status); 

Just like the exit() method , the status can indicate Success or Failure.

Thus , Halt should only be used when we know what we’re doing.

Conclusion

In most circumstances, a program will terminate itself when it reaches the end, but in unusual circumstances, such as exceptions, a developer must know how to terminate a program. Java provides several ways to terminate a program. These include the above mentioned topics. Developers must be cautious when using these termination methods.

With this article at OpenGenus, you must have the complete knowledge to terminate a program in Java using different techniques.

Mohd Ehtesham Uddin Qureshi

Mohd Ehtesham Uddin Qureshi completed B.E in Computer Science from Muffakham Jah College of Engineering and Technology (2021). He is an Intern at OpenGenus.

OpenGenus Tech Review Team

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