拋出java.lang.NullPointerException異常

Question

如何捕獲文件對象返回的空引用null？我不斷收到java.lang.NullPointerException。

public static File getFile() { 
     String filePath = JOptionPane.showInputDialog("Enter the full path to   the file you want to open"); 
     File file = new File(filePath); 
     while(!file.exists()) { 
      filePath = JOptionPane.showInputDialog("Please enter a valid full path"); 
     } 
     return file; 
    } 
} 

Answer 1

的javadoc約public File(String pathname)構造：

NullPointerException - If the pathname argument is null 

所以最好先檢查一下filePath不null，把它傳遞給new File(String path)