## javax.mail.internet
Class ParameterList

    java.lang.Object
      javax.mail.internet.ParameterList

    public class ParameterList

extends java.lang.Object

This class holds MIME parameters (attribute-value pairs). The `mail.mime.encodeparameters` and `mail.mime.decodeparameters` System properties control whether encoded parameters, as specified by RFC 2231, are supported. By default, such encoded parameters are not supported.

Also, in the current implementation, setting the System property `mail.mime.decodeparameters.strict` to `"true"` will cause a `ParseException` to be thrown for errors detected while decoding encoded parameters. By default, if any decoding errors occur, the original (undecoded) string is used.

Constructor Summary
`ParameterList()` No-arg Constructor.
`ParameterList(java.lang.String s)` Constructor that takes a parameter-list string.

Method Summary
`java.lang.String` `get(java.lang.String name)` Returns the value of the specified parameter.
`java.util.Enumeration` `getNames()` Return an enumeration of the names of all parameters in this list.
`void` `remove(java.lang.String name)` Removes the specified parameter from this ParameterList.
`void` `set(java.lang.String name, java.lang.String value)` Set a parameter.
`void` `set(java.lang.String name, java.lang.String value, java.lang.String charset)` Set a parameter.
`int` `size()` Return the number of parameters in this list.
`java.lang.String` `toString()` Convert this ParameterList into a MIME String.
`java.lang.String` `toString(int used)` Convert this ParameterList into a MIME String.

Methods inherited from class java.lang.Object
`clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait`

Constructor Detail

### ParameterList

    public ParameterList()

  No-arg Constructor.

### ParameterList

    public ParameterList(java.lang.String s)
                  throws ParseException

  Constructor that takes a parameter-list string. The String is parsed and the parameters are collected and stored internally. A ParseException is thrown if the parse fails. Note that an empty parameter-list string is valid and will be parsed into an empty ParameterList.

  Parameters:
    `s` - the parameter-list string.
  Throws:
    `ParseException` - if the parse fails.

Method Detail

### size

    public int size()

  Return the number of parameters in this list.

  Returns:
    number of parameters.

### get

    public java.lang.String get(java.lang.String name)

  Returns the value of the specified parameter. Note that parameter names are case-insensitive.

  Parameters:
    `name` - parameter name.
  Returns:
    Value of the parameter. Returns `null` if the parameter is not present.

### set

    public void set(java.lang.String name,
                    java.lang.String value)

  Set a parameter. If this parameter already exists, it is replaced by this new value.

  Parameters:
    `name` - name of the parameter.
    `value` - value of the parameter.

### set

    public void set(java.lang.String name,
                    java.lang.String value,
                    java.lang.String charset)

  Set a parameter. If this parameter already exists, it is replaced by this new value. If the `mail.mime.encodeparameters` System property is true, and the parameter value is non-ASCII, it will be encoded with the specified charset, as specified by RFC 2231.

  Parameters:
    `name` - name of the parameter.
    `value` - value of the parameter.
    `charset` - charset of the parameter value.
  Since:
    JavaMail 1.4

### remove

    public void remove(java.lang.String name)

  Removes the specified parameter from this ParameterList. This method does nothing if the parameter is not present.

  Parameters:
    `name` - name of the parameter.

### getNames

    public java.util.Enumeration getNames()

  Return an enumeration of the names of all parameters in this list.

  Returns:
    Enumeration of all parameter names in this list.

### toString

    public java.lang.String toString()

  Convert this ParameterList into a MIME String. If this is an empty list, an empty string is returned.

  Overrides:
    `toString` in class `java.lang.Object`
  Returns:
    String

### toString

    public java.lang.String toString(int used)

  Convert this ParameterList into a MIME String. If this is an empty list, an empty string is returned. The 'used' parameter specifies the number of character positions already taken up in the field into which the resulting parameter list is to be inserted. It's used to determine where to fold the resulting parameter list.

  Parameters:
    `used` - number of character positions already used, in the field into which the parameter list is to be inserted.
  Returns:
    String