Java：游标当前位置的列号和行号

我想知道游标在JTextArea中的列号和行号。 即。 在记事本中，当我在第一行而不是状态栏时显示Ln 1，Col 1。

提前致谢…

Answer 1

这是代码

import java.awt.BorderLayout; import javax.swing.*; import javax.swing.event.*; public class caretDemo extends JFrame { // Two controls, one is the editor and the other is our little status bar at the bottom. // When we update the editor, the change in caret will update the status text field. private JTextArea editor; private JTextField status; // Start of our caretDemo class public caretDemo() { setTitle("Caret Demo"); setSize(500,500); // Lets create a border layout to make positioning of items easy and quick. setLayout(new BorderLayout()); setDefaultCloseOperation(EXIT_ON_CLOSE); editor = new JTextArea(); // Add a caretListener to the editor. This is an anonymous class because it is inline and has no specific name. editor.addCaretListener(new CaretListener() { // Each time the caret is moved, it will trigger the listener and its method caretUpdate. // It will then pass the event to the update method including the source of the event (which is our textarea control) public void caretUpdate(CaretEvent e) { JTextArea editArea = (JTextArea)e.getSource(); // Lets start with some default values for the line and column. int linenum = 1; int columnnum = 1; // We create a try catch to catch any exceptions. We will simply ignore such an error for our demonstration. try { // First we find the position of the caret. This is the number of where the caret is in relation to the start of the JTextArea // in the upper left corner. We use this position to find offset values (eg what line we are on for the given position as well as // what position that line starts on. int caretpos = editArea.getCaretPosition(); linenum = editArea.getLineOfOffset(caretpos); // We subtract the offset of where our line starts from the overall caret position. // So lets say that we are on line 5 and that line starts at caret position 100, if our caret position is currently 106 // we know that we must be on column 6 of line 5. columnnum = caretpos - editArea.getLineStartOffset(linenum); // We have to add one here because line numbers start at 0 for getLineOfOffset and we want it to start at 1 for display. linenum += 1; } catch(Exception ex) { } // Once we know the position of the line and the column, pass it to a helper function for updating the status bar. updateStatus(linenum, columnnum); } }); // Add the fields to the layout, the editor in the middle and the status at the bottom. add(editor, BorderLayout.CENTER); status = new JTextField(); add(status, BorderLayout.SOUTH); // Give the status update value updateStatus(1,1); } // This helper function updates the status bar with the line number and column number. private void updateStatus(int linenumber, int columnnumber) { status.setText("Line: " + linenumber + " Column: " + columnnumber); } // Entry point to the program. It kicks off by creating an instance of our class and making it visible. public static void main(String args[]) { caretDemo caretDemoApp = new caretDemo(); caretDemoApp.setVisible(true); } } 

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产量

Answer 2

您需要使用Utilities.getRowStart以及插入位置，如下所示：

要获取行号：

 int caretPos = textArea.getCaretPosition(); int rowNum = (caretPos == 0) ? 1 : 0; for (int offset = caretPos; offset > 0;) { offset = Utilities.getRowStart(textArea, offset) - 1; rowNum++; } System.out.println("Row: " + rowNum); 

要获取列号：

 int offset = Utilities.getRowStart(textArea, caretPos); int colNum = caretPos - offset + 1; System.out.println("Col: " + colNum); 

Answer 3

你试过getCaretPosition吗？

您必须计算\n以了解您拥有哪一行，并且您必须计算当前插入符号位置与\n字符的最后一次出现之间的差异。