Java Utililty Methods File Extension Name Get

if (f.isFile()) {
    String name = f.getName();
    int pos = name.lastIndexOf(".");
    if (pos != -1) {
        return name.substring(pos + 1, name.length());
return "";
...

String ext = null;
String str = f.getName();
int ind = str.lastIndexOf('.');
if (ind > 0 && ind < str.length() - 1) {
    ext = str.substring(ind + 1).toLowerCase();
return ext;

if (file == null) {
    return null;
String fileName = file.getName();
int dotPos = fileName.lastIndexOf('.');
return dotPos == -1 ? null : fileName.substring(dotPos + 1);

String extension = file.getAbsolutePath().substring(file.getAbsolutePath().lastIndexOf('.') + 1);
return extension;

String filename = file.getName();
int extensionIndex = filename.lastIndexOf(".");
String extension;
if (extensionIndex == -1) {
    extension = "";
} else {
    extension = filename.substring(extensionIndex + 1, filename.length());
return extension;

return file.getName().substring(file.getName().lastIndexOf(".") + 1);

String name = file.getName();
int posLastDot = name.lastIndexOf('.');
if (posLastDot < 0) {
    return null;
return name.substring(posLastDot + 1);

if (file.isFile())
    return getFileExtension(file.getName());
else
    return "" + File.separatorChar;

if (file != null) {
    String fileName = file.getName();
    if (fileName.lastIndexOf(".") != -1) {
        String extension = fileName.substring(fileName.lastIndexOf(".") + 1);
        return extension;
    } else {
        return "";
} else {
    return null;

String name = file.getName();
int pos = name.lastIndexOf('.');
String extension = ((pos >= 0) && (pos < name.length() - 1)) ? name.substring(pos + 1).trim().toLowerCase()
        : null;
return extension;