Java: Why checking for "\n" doesn't match new lines added using System.getProperty("line.separator")
java, newline
Solution
First, I think that "\n" is equivalent to System.getProperty("line.separator") except that the later is platform independent.
No, the latter is platform-specific. It's the platform-independent way of getting your platform's line separator.
So on Windows, I'd expect `System.getProperty("line.separator")` to return "\r\n", for example.
Now as for what your `textArea` uses for a new-line - that entirely depends on what `textArea` is - and you haven't given us any information about that.
Problem
(Updated Question) First, I think that `"\n"` is equivalent to `System.getProperty("line.separator")` I wrote some methods to work with Strings some of them check for existence of new line `if (string.charAt(i) == '\n') {//do something;}` But I noticed that checking for `"\n"` doesn't match the new lines added by the `System.getProperty("line.separator")` This is an SSCCE to demonstrate my claim!: Description: Two strings of identical text; one `alpha_String` has new lines added using `"\n"`, and the other `beta_String` has new lines added using `System.getProperty("line.separator")` There is a method named `String removeExtraNewLines(String)` used to remove any extra new lines in a String and return it back; as its header suggests. The two strings filtered using this method. The two buttons `buttonAlpha` and `buttonBeta` each set the text of the `JTextArea` with the filtered String You will notice that the the method catch/match and remove extra new lines of `alpha_String` but don't do the same with `beta_String` ``` import java.awt.BorderLayout; import java.awt.event.ActionEvent; import javax.swing.*; public class NewLineTest extends JPanel { JPanel buttonPanel; JPanel textAreaPanel; JButton buttonAlpha; JButton buttonBeta; JTextArea textArea; String n = "\n"; String s = System.getProperty("line.separator"); String alpha_String; String beta_String; public NewLineTest() { createSentencesText(); buttonAlpha = new JButton("Alpha String"); buttonAlpha.addActionListener(eventWatcher); buttonBeta = new JButton("Beta String"); buttonBeta.addActionListener(eventWatcher); textArea = new JTextArea(0, 0); JScrollPane scrollTextArea = new JScrollPane(textArea); scrollTextArea.setVerticalScrollBarPolicy(JScrollPane.VERTICAL_SCROLLBAR_ALWAYS); textArea.setEditable(false); buttonPanel = new JPanel(); textAreaPanel = new JPanel(new BorderLayout()); buttonPanel.add(buttonAlpha); buttonPanel.add(buttonBeta); textAreaPanel.add(scrollTextArea, BorderLayout.CENTER); JSplitPane splitPane = new JSplitPane(JSplitPane.HORIZONTAL_SPLIT, textAreaPanel, buttonPanel); splitPane.setDividerLocation(400); splitPane.setResizeWeight(.5d); this.setLayout(new BorderLayout()); this.add(splitPane); } private void createSentencesText() { alpha_String = "A: Let’s go to the beach." + n + n + "B: That’s a great idea." + n + "A: We haven’t been in a while." + n + n + "B: We haven’t been in a month." + n + "A: The last time we went, you almost drowned." + n + "B: No, I didn’t." + n + n + n + "A: Then why did the lifeguard dive into the water?" + n + "B: I think he wanted to cool off." + n + "A: He swam right up to you." + n + "B: And then he turned right around." + n + "A: Maybe you’re right." + n + "B: Maybe we should get going."; beta_String = "A: Let’s go to the beach." + s + s + "B: That’s a great idea." + s + "A: We haven’t been in a while." + s + s + "B: We haven’t been in a month." + s + "A: The last time we went, you almost drowned." + s + "B: No, I didn’t." + s + s + s + "A: Then why did the lifeguard dive into the water?" + s + "B: I think he wanted to cool off." + s + "A: He swam right up to you." + s + "B: And then he turned right around." + s + "A: Maybe you’re right." + s + "B: Maybe we should get going."; } public static String removeExtraNewLines(String s) { String myNewString = s.trim(); StringBuilder stringB = new StringBuilder(); char previouseChar = '~'; for (int i = 0; i < myNewString.length(); i++) { if (i > 1) { previouseChar = myNewString.charAt(i - 1); } if ((myNewString.charAt(i) == '\n') && (previouseChar == '\n')) { continue; } stringB.append(myNewString.charAt(i)); } myNewString = stringB.toString(); return myNewString; } AbstractAction eventWatcher = new AbstractAction() { @Override public void actionPerformed(ActionEvent ae) { Object source = ae.getSource(); if (source == buttonAlpha) { String arranged_string_alpha = removeExtraNewLines(alpha_String); textArea.setText(arranged_string_alpha); } if (source == buttonBeta) { String arranged_string_beta = removeExtraNewLines(beta_String); textArea.setText(arranged_string_beta); } } }; private static void createAndShowGUI() { JFrame frame = new JFrame("NewLine Test"); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); frame.setSize(700, 300); frame.add(new NewLineTest(), BorderLayout.CENTER); frame.setVisible(true); } public static void main(String[] args) { SwingUtilities.invokeLater(new Runnable() { public void run() { UIManager.put("swing.boldMetal", Boolean.FALSE); createAndShowGUI(); } }); } } ``` So the question: Why checking for `"\n"` doesn't match new lines added using `System.getProperty("line.separator")`?, And How to match them?