How to call the main () method of one class in another class?

Question

How do I call the main() method of one class in another class? I have two classes SaveData and DynamicTest . Both classes contain the main() method. I would like to run my main DynamicTest class. What is the correct name for SaveData ?

 public class SaveData { private static final Map<String, Object> myCachedTreeMap = new TreeMap<String, Object>(); public static final List<String> getLines(final String resourceParam, final Charset charset) throws IOException{ System.out.println("Please get: "+resourceParam); if (myCachedTreeMap.containsKey(resourceParam) ) { // Use the cached file, to prevent an additional read. System.out.println("Found in memory : "+resourceParam); } else { // Load the file from disk System.out.println("Not Found in memory : "+resourceParam); } return null; } public static void main(String[] args) throws IOException { String target_dir = "C:\\myfiles\\config\\en"; String output = "C:\\myfiles\\config\\en\\output.txt"; File dir = new File(target_dir); File[] files = dir.listFiles(); if (files == null || files.length < 1) { System.out.println("File list is empty..."); return; } // open the Printwriter PrintWriter outputStream = new PrintWriter(output); try { for (File textFile : files) { if (textFile.isFile() && textFile.getName().endsWith(".txt")) { readFromDisk(textFile); } } } finally { outputStream.close(); } String fileNameFromCache = "en_synonyms.txt"; Object Sheet1 = myCachedTreeMap.get(fileNameFromCache); System.out.println(fileNameFromCache + " : \n" + Sheet1); } @SuppressWarnings("resource") private static void readFromDisk(File textFile) throws FileNotFoundException, IOException { BufferedReader inputStream; inputStream = null; String content = ""; try { inputStream = new BufferedReader(new FileReader(textFile)); content = readFile(textFile); System.out.println("Bytes Read = "+content.length()); // Save contents FileContentsObject Sheet1 = new FileContentsObject(System.currentTimeMillis(), textFile.lastModified(), content, textFile.getName(), getLines(null, null)); // add to map myCachedTreeMap.put(textFile.getName(), Sheet1); } finally { if (inputStream != null) { inputStream.close(); } } } private static String readFile(File f) throws FileNotFoundException, IOException, UnsupportedEncodingException { StringBuilder text = new StringBuilder(1024); int read, N = 1024 * 1024; char[] buffer = new char[N]; BufferedReader br = null; try { br = new BufferedReader( new InputStreamReader( new FileInputStream(f), "UTF8")); while(true) { read = br.read(buffer, 0, N); if (read > 0) text.append(new String(buffer, 0, read)); if(read < N) { break; } } } finally { if (br != null) br.close(); } return text.toString(); } private static final class FileContentsObject { private long cachedTime; // currentTime private long lastModifiedTimestamp; private String contents; List<String> lines; private String fileName; public FileContentsObject(long cachedTime, long lastModifiedTimestamp, String contents, String fileName, List<String> lines) { this.cachedTime = cachedTime; this.lastModifiedTimestamp = lastModifiedTimestamp; this.contents = contents; this.fileName = fileName; this.lines = lines; SimpleDateFormat sdf = new SimpleDateFormat("MM/dd/yy HH:mm:ss"); System.out.println("Current Time & Date:" + sdf.format(cachedTime)); System.out.println("Last Modified Time Stamp:" + sdf.format(lastModifiedTimestamp)); } /** * * @return The lines from the file */ List<String> getLines() { return this.lines; } public String toString() { return "Sheet1{" + "fileName='" + fileName + '\'' + ", contents='" + contents + '\'' + ", lastModifiedTimestamp=" + lastModifiedTimestamp + ", CurrentTime&Date=" + cachedTime + '}'; } } } 

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 public class DynamicTest { public static void main(String[] args) { Charset charset = Charset.forName("UTF-8"); try { List<String> lines = CacheData.getLines("en_synonyms", charset) ; if (lines != null) { System.out.println("Number of Lines: "+lines.size()); for (String line:lines) { System.out.println("DynamicTest:: "+line); } } } catch (IOException e) { e.printStackTrace(); } try { List<String> lines = CacheData.getLines("en_stopwords", charset) ; if (lines != null) { System.out.println("Number of Lines: "+lines.size()); for (String line:lines) { System.out.println("DynamicTest:: "+line); } } } catch (IOException e) { e.printStackTrace(); } } } 

Answer 1

You call it like any other static method call:

 SaveData.main (args); // it up to you whether to pass the same args or // different args 

Answer 2

In the main DynamicTest method write this SaveData.main(args);

Static method call:

 Class.method(); 

Non-static method call:

 Class object = new Class(); object.method(); 

Answer 3

The main declaration is always static , so you should call it, like other static methods, in your case:

 SaveData.main (args);