Check whether a path is relative or absolute

Question

I wonder if there is a Java function that checks whether the string is a relative path or not:

Ex:

String caminho = funcao("\\pasta\\arquivo.xml")  // retorna true que é um caminho relativo
String caminho2 = funcao("c:\\pasta\\arquivo.xml") // retorna false não é caminho relativo

Or also if there is already some function that I pass the string it returns me the complete path:

Ex:

String caminho3 = funcao("\\pasta\\arquivo.xml"); // retorno: c:\pasta\arquivo.xml
String caminho4 = funcao("c:\\pasta\\arquivo.xml");  // retorno: c:\pasta\arquivo.xml

Answer 1

Check relative path

The method File.isAbsolute() says if the path is absolute. Then just deny (!) the return to know if it is relative.

Take an example:

File f1 = new File("..");
System.out.println("\"" + f1.getPath() + "\" -> " + f1.isAbsolute());

File f2 = new File("c:\\temp");
System.out.println("\"" + f2.getPath() + "\" -> " + f2.isAbsolute());

This will print:

".." -> false

"c: temp" -> true

Recovering the absolute path

To return the full path use the method getAbsolutePath() of a class instance File.

See one more example:

File arquivo1 = new File("\\pasta\\arquivo.xml");
System.out.println("\"" + arquivo1.getPath() + "\" -> " + arquivo1.getAbsolutePath());

File arquivo2 = new File("c:\\pasta\\arquivo.xml");
System.out.println("\"" + arquivo2.getPath() + "\" -> " + arquivo2.getAbsolutePath());

This will print:

"\folder.xml file" -> C: folder.xml file

"c: .xml file folder" -> c: .xml file folder

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Note: Java does not use the term function, we usually call them methods since they are always members of classes.