![\"\"](\"https:\/\/www.baeldung.com\/wp-content\/uploads\/2016\/10\/social-Core-Java-4.jpg\")
<\/p>\n<\/p>\n
<\/p>\n
We know that it’s possible to stop execution after a certain time<\/a> duration in Java. Sometimes, there may be scenarios where we want to stop the execution of further code under certain conditions. In this tutorial, we’ll explore different solutions to this problem.<\/p>\n Stopping the execution of further code can be useful in situations where we want to terminate a long-running process, interrupt<\/a> a running Thread,<\/em> or handle exceptional cases.\u00a0This enhances control and flexibility in our program.<\/p>\n Stopping the execution of further code enables efficient resource utilization, allows proper error handling, and allows graceful handling of unexpected situations.<\/strong> This can be helpful in these areas:<\/p>\n An example could be running a Thread<\/em> in the background. We know that creating and running a Thread<\/em> is costly in computational terms. When we no longer need a background Thread, <\/em>we should interrupt and stop it to save computational resources:<\/p>\n Mathematically, the factorial of a non-negative integer n, denoted as n!, is the product of all positive integers from 1 up to n. <\/span><\/strong>The factorial function can be defined recursively:<\/p>\n The calculateFactorial(n)<\/em> method below calculates the product of all positive integers less or equal to n<\/em>:<\/p>\n Here, we use the return<\/em> statement as the base case of this recursive function. If n<\/em> is 1<\/em> or less, the function returns 1<\/em>. But if n<\/em> is greater than or equal to 2<\/em>, the function calculates the factorial and returns the value.<\/p>\n Another example of a return<\/em> statement could be downloading a file. If fileUrl<\/em> and destinationPath<\/em> are null <\/em>or empty in the download()<\/em> method, we stop executing further code:<\/p>\n To calculate the sum of an array, we can use a simple Java for<\/em> loop<\/a>.\u00a0 But when there is a negative value in the array the method stops calculating further values of the array, and the break<\/em> statement terminates the loop.<\/strong> As a result, the control flow is redirected to the statement immediately following the end of the for loop<\/em>:<\/p>\n To exit a particular iteration of a loop, we can use the break<\/em> statement to exit out of the scope of the loop:<\/p>\n A labeled\u00a0break<\/em> terminates the outer loop. <\/strong>Once the outer loop completes its iterations, the program’s execution naturally moves to the subsequent statement.<\/p>\n Here, the processLines() <\/em>method takes an array of String\u00a0<\/em>and prints the line. However, when the program encounters a stop<\/em> in the array, it discontinues printing the line and exits the labeled loop’s scope using the break<\/em> statement:<\/p>\n To stop the execution of further code, we can use a flag variable. <\/em>System.exit(0) <\/em>is commonly used to terminate the currently running Java program with an exit status of 0<\/em>.<\/strong><\/p>\n Here, we use conditional statements to determine whether the program should continue running or terminate:<\/p>\n We terminate the program using System.exit(0)<\/em><\/a> before reaching the return<\/em> statement if shouldContinue<\/em> is false<\/em>.<\/p>\n If the performTask()<\/em> method is called with the arguments 10<\/em> and 20<\/em>, and the shouldContinue<\/em> state is false<\/em>, the program halts its execution. Rather than giving the sum of the numbers, this method terminates the program:<\/p>\n There are a lot of long-running tasks when doing batch processing. We can notify the operating system about the status after finishing batch processing. When we use System.exit(statusCode)<\/em>, the operating system can determine whether the shutdown was normal or abnormal. We can use System.exit(0)<\/em> for normal shutdowns and System.exit(1)<\/em> for abnormal shutdowns.<\/p>\n Exceptions are unexpected errors or abnormal conditions that applications face and need to be handled appropriately.<\/strong> It’s essential to know about errors and exceptions<\/a>. In this example, we need generics to check the parameter type. If the parameter type is Number,\u00a0<\/em>we use an Exception<\/em> to stop the execution of the method:<\/p>\n Here, we see that whenever we pass a Number<\/em> as a parameter, it throws an Exception<\/em>. On the other hand, if we pass String<\/em> as the input parameter, it returns the uppercase of the given String<\/em>:<\/p>\n In this example, we used the basics of Java generics<\/a>. Generics are useful for type safety, compile-time type checking, collection framework, etc.<\/p>\n Let’s create a class called InterruptThread<\/em> to use the interrupt()<\/em> method in a running thread.<\/p>\n When a thread is interrupted, it sets the interrupt flag of the thread, indicating that it has been requested to stop<\/strong>. If the thread gets an interrupt signal, it stops the while loop<\/em> scope in the program:<\/p>\n We need to start a thread<\/a> using the start()<\/em> method and pause the program for 2000ms. Then using the interrupt()<\/em> signal stops the execution in the while loop<\/em> and stops the thread:<\/p>\n In this article, we’ve explored multiple programmatic ways to stop the execution of further code in Java programs. To halt a program, we can use System.exit(0)\u00a0<\/em>for immediate termination. Alternatively, return<\/em> and break<\/em> statements help to exit particular methods or loops, while exceptions allow for the interruption of code execution.<\/p>\n As always, the complete code samples for this article can be found over on GitHub<\/a>.<\/p>\n Explore multiple programmatic ways to stop the execution of further code in Java programs.<\/p>\n2. Introduction to the Problem<\/h2>\n
<\/div>\n\n
@Override\r\npublic void run() {\r\n while (!isInterrupted()) {\r\n if (isInterrupted()) {\r\n break;\r\n }\r\n \/\/ complex calculation\r\n }\r\n}<\/code><\/pre>\n3. Using the return<\/em>\u00a0Statement<\/h2>\n
<\/div>\nn! = n * (n - 1)!\r\n0! = 1\r\n<\/code><\/pre>\nint calculateFactorial(int n) {\r\n if (n <= 1) {\r\n return 1; \/\/ base case\r\n }\r\n return n * calculateFactorial(n - 1);\r\n}<\/code><\/pre>\nvoid download(String fileUrl, String destinationPath) throws MalformedURLException {\r\n if (fileUrl == null || fileUrl.isEmpty() || destinationPath == null || destinationPath.isEmpty()) {\r\n return;\r\n }\r\n \/\/ execute downloading\r\n URL url = new URL(fileUrl);\r\n try (InputStream in = url.openStream(); FileOutputStream out = new FileOutputStream(destinationPath)) {\r\n byte[] buffer = new byte[1024];\r\n int bytesRead;\r\n while ((bytesRead = in.read(buffer)) != -1) {\r\n out.write(buffer, 0, bytesRead);\r\n }\r\n } catch (IOException e) {\r\n throw new RuntimeException(e);\r\n }\r\n}<\/code><\/pre>\n4. Using break<\/em> Statements in Loops<\/h2>\n
<\/div>\nint calculateSum(int[] x) {\r\n int sum = 0;\r\n for (int i = 0; i < 10; i++) {\r\n if (x[i] < 0) {\r\n break;\r\n }\r\n sum += x[i];\r\n }\r\n return sum;\r\n}<\/code><\/pre>\n@Test\r\nvoid givenArrayWithNegative_whenStopExecutionInLoopCalled_thenSumIsCalculatedIgnoringNegatives() {\r\n StopExecutionFurtherCode stopExecutionFurtherCode = new StopExecutionFurtherCode();\r\n int[] nums = { 1, 2, 3, -1, 1, 2, 3 };\r\n int sum = stopExecutionFurtherCode.calculateSum(nums);\r\n assertEquals(6, sum);\r\n}<\/code><\/pre>\n5. Using a break<\/em> Statement in Labeled Loops<\/h2>\n
<\/div>\nint processLines(String[] lines) {\r\n int statusCode = 0;\r\n parser:\r\n for (String line : lines) {\r\n System.out.println("Processing line: " + line);\r\n if (line.equals("stop")) {\r\n System.out.println("Stopping parsing...");\r\n statusCode = -1;\r\n break parser; \/\/ Stop parsing and exit the loop\r\n }\r\n System.out.println("Line processed.");\r\n }\r\n return statusCode;\r\n}<\/code><\/pre>\n6. Using a boolean<\/em> Variable<\/h2>\n
<\/div>\npublic class StopExecutionFurtherCode {\r\n boolean shouldContinue = true;\r\n int performTask(int a, int b) {\r\n if (!shouldContinue) {\r\n System.exit(0);\r\n }\r\n return a + b;\r\n }\r\n void stop() {\r\n this.shouldContinue = false;\r\n }\r\n}<\/code><\/pre>\nStopExecutionFurtherCode stopExecution = new StopExecutionFurtherCode();\r\nstopExecution.stop();\r\nint performedTask = stopExecution.performTask(10, 20);<\/code><\/pre>\n7. Using an Exception<\/em><\/h2>\n
<\/div>\n<T> T stopExecutionUsingException(T object) {\r\n if (object instanceof Number) {\r\n throw new IllegalArgumentException("Parameter can not be number.");\r\n }\r\n T upperCase = (T) String.valueOf(object).toUpperCase(Locale.ENGLISH);\r\n return upperCase;\r\n}<\/code><\/pre>\n@Test\r\nvoid givenName_whenStopExecutionUsingExceptionCalled_thenNameIsConvertedToUpper() {\r\n StopExecutionFurtherCode stopExecutionFurtherCode = new StopExecutionFurtherCode();\r\n String name = "John";\r\n String result1 = stopExecutionFurtherCode.stopExecutionUsingException(name);\r\n assertEquals("JOHN", result1);\r\n try {\r\n Integer number1 = 10;\r\n assertThrows(IllegalArgumentException.class, () -> {\r\n int result = stopExecutionFurtherCode.stopExecutionUsingException(number1);\r\n });\r\n } catch (Exception e) {\r\n Assert.fail("Unexpected exception thrown: " + e.getMessage());\r\n }\r\n}<\/code><\/pre>\n8. Using the interrupt()<\/em> Method in Thread<\/em><\/h2>\n
<\/div>\nclass InterruptThread extends Thread {\r\n @Override\r\n public void run() {\r\n while (!isInterrupted()) {\r\n if (isInterrupted()) {\r\n break;\r\n }\r\n \/\/ business logic\r\n }\r\n }\r\n}\r\n<\/code><\/pre>\n@Test\r\nvoid givenThreadRunning_whenInterruptCalled_thenThreadExecutionIsStopped() throws InterruptedException {\r\n InterruptThread stopExecution = new InterruptThread();\r\n stopExecution.start();\r\n Thread.sleep(2000);\r\n stopExecution.interrupt();\r\n stopExecution.join();\r\n assertTrue(!stopExecution.isAlive());\r\n}<\/code><\/pre>\n9. Conclusion<\/h2>\n
<\/div>\n<\/p>\n
![](\"https:\/\/assets.feedblitz.com\/i\/fblike20.png\")
<\/a> ![](\"https:\/\/assets.feedblitz.com\/i\/pinterest20.png\")
<\/a> ![](\"https:\/\/assets.feedblitz.com\/i\/twitter20.png\")
<\/a> ![](\"https:\/\/assets.feedblitz.com\/i\/email20.png\")
<\/a> ![](\"https:\/\/assets.feedblitz.com\/i\/rss20.png\")
<\/a> ![](\"https:\/\/assets.feedblitz.com\/i\/comments20.png\")
<\/a> ![](\"https:\/\/assets.feedblitz.com\/i\/commentsrss20.png\")
<\/a> <\/div>\n\n![\\\"IT\u96fb\u8166\u88dc\u7fd2](\\\"http:\/\/itteacheritfreelance.hk\/test\/wordpress\/wp-content\/uploads\/2016\/05\/logo2-2.png\\\"){kind=logo}
\r\nwww.itsec.hk<\/a>
\r\nwww.itsec.vip<\/a>
\r\nwww.itseceu.uk<\/a>
<\/p>","protected":false},"excerpt":{"rendered":"<\/p>\n<\/a>\u00a0<\/a>\u00a0<\/a>\u00a0<\/a>\u00a0<\/a>\u00a0<\/a>\u00a0<\/a>\u00a0<\/div>\n<\/div>","protected":false},"author":214,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"slim_seo":{"title":"Stop Executing Further Code in Java - ITTeacherITFreelance.hk","description":"Explore multiple programmatic ways to stop the execution of further code in Java programs. \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0"},"footnotes":""},"categories":[6,1307],"tags":[],"_links":{"self":[{"href":"https:\/\/itteacheritfreelance.hk\/wordpress\/index.php\/wp-json\/wp\/v2\/posts\/326904"}],"collection":[{"href":"https:\/\/itteacheritfreelance.hk\/wordpress\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/itteacheritfreelance.hk\/wordpress\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/itteacheritfreelance.hk\/wordpress\/index.php\/wp-json\/wp\/v2\/users\/214"}],"replies":[{"embeddable":true,"href":"https:\/\/itteacheritfreelance.hk\/wordpress\/index.php\/wp-json\/wp\/v2\/comments?post=326904"}],"version-history":[{"count":1,"href":"https:\/\/itteacheritfreelance.hk\/wordpress\/index.php\/wp-json\/wp\/v2\/posts\/326904\/revisions"}],"predecessor-version":[{"id":326905,"href":"https:\/\/itteacheritfreelance.hk\/wordpress\/index.php\/wp-json\/wp\/v2\/posts\/326904\/revisions\/326905"}],"wp:attachment":[{"href":"https:\/\/itteacheritfreelance.hk\/wordpress\/index.php\/wp-json\/wp\/v2\/media?parent=326904"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/itteacheritfreelance.hk\/wordpress\/index.php\/wp-json\/wp\/v2\/categories?post=326904"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/itteacheritfreelance.hk\/wordpress\/index.php\/wp-json\/wp\/v2\/tags?post=326904"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}