https://www.tutorialspoint.com/java/java_properties_class.htm
Properties는 String값을 가지는 Key와 Value의 쌍으로 이루어진 리스트를 가지는 Hashtable의 하위 클래스이다.
Properties는 다른 많은 java 클래스에 사용된다.
Properties 클래스는 다음과 같은 메서드를 가진다.
String getProperty(String key)
Returns the value associated with the key. A null object is returned if the key is neither in the list nor in the default property list.
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String getProperty(String key, String defaultProperty)
Returns the value associated with the key; defaultProperty is returned if the key is neither in the list nor in the default property list.
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void list(PrintStream streamOut)
Sends the property list to the output stream linked to streamOut.
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void list(PrintWriter streamOut)
Sends the property list to the output stream linked to streamOut.
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void load(InputStream streamIn) throws IOException
Inputs a property list from the input stream linked to streamIn.
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Enumeration propertyNames( )
Returns an enumeration of the keys. This includes those keys found in the default property list, too.
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Object setProperty(String key, String value)
Associates value with the key. Returns the previous value associated with the key, or returns null if no such association exists.
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void store(OutputStream streamOut, String description)
After writing the string specified by description, the property list is written to the output stream linked to streamOut.
