java - JOptionPane showInputDialog cancel button NullPointerException -
i trying unsuccessfully trap user entering filename. i'm using input dialog because path , extension predetermined, , need append filename after user enters it. title says nullpointerexception time user clicks cancel button. since input dialog has no way remove cancel button i've resorted method:
while (filename.equals(null) || filename.equals("")) { filename=joptionpane.showinputdialog(this, "please enter filename."); if (filename.equals(null)) filename=""; }
i wouldn't have filename.equals(null) in 2 places that, tried both separately , out of frustration tried too. nullpointerexception still occurs on line:
if (filename.equals(null)) filename="";
is there way trap cancel button (null) or prevent it?
filename.equals(null) // compare object
should like
filename == null // compare object references
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