如何检查是否已从TextView中删除一行？

Question

I am making an ide and use a TextView to display line numbers based on my EditText's line count. I have it working with adding new lines but how can I check to see if a line has been deleted and decrease the TextView's line count?

et.setOnKeyListener(new OnKeyListener() {

@Override
public boolean onKey(View v, int keyCode, KeyEvent event) {
    if ((event.getAction() == KeyEvent.ACTION_DOWN) &&
        (keyCode == KeyEvent.KEYCODE_ENTER)) {
        lines++;
        lineNumbers.append(lines+"\n");            
    }
    return false;
}

});

Answer 1

This did the job.

private void openFile(final File aFile) {
        String nullChk = et.getText().toString();
        exists = true;

        if (!changed || nullChk.matches("")) {
            try {
                currentFile = aFile;
                et.setText(new Scanner(currentFile).useDelimiter("\\Z").next());
                lineNumbers.setText("");
                lines = 1;

                for (int i = 1; i < et.getLineCount(); i++) {
                    lineNumbers.append(lines + "\n");
                    lines++;
            ...
}

et.setOnKeyListener(new OnKeyListener() {

            @Override
            public boolean onKey(View v, int keyCode, KeyEvent event) {
                if ((event.getAction() == KeyEvent.ACTION_DOWN)
                        && (keyCode == KeyEvent.KEYCODE_ENTER)) {
                    lines++;
                    lineNumbers.append(lines + "\n");
                }
                if ((event.getAction() == KeyEvent.ACTION_DOWN)
                        && (keyCode == KeyEvent.KEYCODE_DEL)) {
                    lineNumbers.setText("");
                    lines = 0;

                    for (int i = 1; i < et.getLineCount(); i++) {
                        lines++;
                        lineNumbers.append(lines + "\n");
                    }
                }
                return false;
            }
        });