ADDITIONAL SYSTEM INFORMATION :
windows10 / java version "1.8.0_211"

A DESCRIPTION OF THE PROBLEM :
    @Test
    public void testFileExist() {
        File xlsFile = new File("test.xls");
        System.out.println(xlsFile.exists());// true

        File xlsFile2 = new File("test2.xls");
        System.out.println(xlsFile2.exists());// false

        File txtFile = new File("test.txt");
        System.out.println(txtFile.exists());// false
    }