📄 getset.htm
字号:
<HTML>
<HEAD>
<META http-equiv="Content-Type" content="text/html; charset=UTF-8">
<TITLE>Getting and Setting Java Type Values in a Preference (Java Developers Almanac Example)
</TITLE>
<META CONTENT="Patrick Chan" NAME="AUTHOR">
<META CONTENT="Code Examples from The Java Developers Almanac 1.4" NAME="DESCRIPTION">
<META CONTENT="Addison-Wesley/Patrick Chan" NAME="OWNER">
<META CONTENT="3/20/02" NAME="revision">
<META CONTENT="no-cache" HTTP-EQUIV="Pragma">
<LINK href="/almanac.css" media="screen" type="text/css" rel="stylesheet">
</HEAD>
<BODY>
<TABLE CELLSPACING="0" CELLPADDING="0" BORDER="0">
<TR>
<TD></TD>
</TR>
</TABLE>
<br>
<TABLE CELLSPACING="0" CELLPADDING="0" BORDER="0">
<TR>
<TD></TD>
</TR>
<TR>
<TD rowspan="3"><A HREF="/?l=ex"><IMG BORDER="0" ALIGN="BOTTOM" HSPACE="10" SRC="/egs/almanac14a.jpg"></A></TD><TD VALIGN="top">
<h1>The Java Developers Almanac 1.4</h1>
<br>
Order this book from <a href="/cgi-bin/scripts/redirect.pl?l=ex&url=http://www.amazon.com/exec/obidos/ASIN/0201752808/xeo">Amazon</a>.
</TD>
</TR>
<TR>
<TD align="right" valign="bottom">
<FORM method="get" action="/cgi-bin/search/find.pl">
<INPUT size="25" name="words" type="text"><INPUT value="Search" type="submit">
</FORM>
</TD>
</TR>
</TABLE>
<HR color="#6666cc">
<TABLE CELLSPACING="0" CELLPADDING="0" BORDER="0">
<TR>
<TD valign="top"><script type="text/javascript">
<!--
google_ad_client = "pub-6001183370374757";
google_ad_width = 120;
google_ad_height = 600;
google_ad_format = "120x600_as";
google_ad_channel = "4777242811";
google_ad_type = "text_image";
google_color_border = "FFFFFF";
google_color_bg = "FFFFFF";
google_color_link = "6666CC";
google_color_url = "6666CC";
google_color_text = "000000";
//--></script><script src="http://pagead2.googlesyndication.com/pagead/show_ads.js" type="text/javascript"></script></TD><TD> </TD><TD valign="top">
<DIV ALIGN="LEFT">
<A HREF="/">Home</A>
>
<A HREF="../index.html">List of Packages</A>
>
<B><A HREF="../java.util.prefs/pkg.html">java.util.prefs</A></B><font color="#666666" class="xsmall-font">
[18 examples]
</font>
</DIV><P>
<h3>e409. Getting and Setting Java Type Values in a Preference</h3>
A preference node holds only string values. However, the
<code>Preferences</code> class has convenience methods that will convert a
number of basic Java types to and from strings. For example,
<code>Preferences.putByteArray()</code> converts a byte array into a string
and then saves the string value. <code>Preferences.getByteArray()</code>
converts the string back into an array of bytes.
<P> The types for which there are conversion methods are
<code>boolean</code>, <code>int</code>, <code>long</code>, <code>float</code>, <code>double</code>, and
<code>byte[]</code>. For all other types, serialization can be used to
convert an arbitrary Java type into a byte array (see
<a href="../java.io/SerializeObj.html" class="eglink"><b>e44</b> Serializing an Object</a>).
<P> See also <a href="../java.util.prefs/Max.html" class="eglink"><b>e410</b> Getting the Maximum Size of a Preference Key and Value</a>.
<pre> // Retrieve the user preference node for the package com.mycompany
Preferences prefs = Preferences.userNodeForPackage(<font color="#0066ff"><i>com.mycompany.MyClass.class</i></font>);
// Preference key name
final String PREF_NAME = <font color="#0066ff"><i>"name_of_preference"</i></font>;
// Save
prefs.put(PREF_NAME, <font color="#0066ff"><i>"a string"</i></font>); // String
prefs.putBoolean(PREF_NAME, <font color="#0066ff"><i>true</i></font>); // boolean
prefs.putInt(PREF_NAME, <font color="#0066ff"><i>123</i></font>); // int
prefs.putLong(PREF_NAME, <font color="#0066ff"><i>123L</i></font>); // long
prefs.putFloat(PREF_NAME, <font color="#0066ff"><i>12.3F</i></font>); // float
prefs.putDouble(PREF_NAME, <font color="#0066ff"><i>12.3</i></font>); // double
byte[] bytes = new byte[<font color="#0066ff"><i>1024</i></font>];
prefs.putByteArray(PREF_NAME, <font color="#0066ff"><i>bytes</i></font>); // byte[]
// Retrieve
String s = prefs.get(PREF_NAME, <font color="#0066ff"><i>"a string"</i></font>); // String
boolean b = prefs.getBoolean(PREF_NAME, <font color="#0066ff"><i>true</i></font>); // boolean
int i = prefs.getInt(PREF_NAME, <font color="#0066ff"><i>123</i></font>); // int
long l = prefs.getLong(PREF_NAME, <font color="#0066ff"><i>123L</i></font>); // long
float f = prefs.getFloat(PREF_NAME, <font color="#0066ff"><i>12.3F</i></font>); // float
double d = prefs.getDouble(PREF_NAME, <font color="#0066ff"><i>12.3</i></font>); // double
bytes = prefs.getByteArray(PREF_NAME, <font color="#0066ff"><i>bytes</i></font>); // byte[]
</pre>
<P><table width="600" CELLSPACING="0" CELLPADDING="2" BORDER="0">
<tr>
<td bgcolor="#6666cc" align="center"><font color="#ffffff">
<b>Related Examples</b></font></td>
</tr>
</table>
e405. <a class="eglink" href="BasicGetSet.html?l=rel">
Saving and Retrieving a Preference Value
</a>
<br>
e406. <a class="eglink" href="Contains.html?l=rel">
Determining If a Preference Node Contains a Specific Key
</a>
<br>
e407. <a class="eglink" href="ContainsValue.html?l=rel">
Determining If a Preference Node Contains a Specific Value
</a>
<br>
e408. <a class="eglink" href="RemovePref.html?l=rel">
Removing a Preference from a Preference Node
</a>
<br>
e410. <a class="eglink" href="Max.html?l=rel">
Getting the Maximum Size of a Preference Key and Value
</a>
<br>
<table width="600" CELLSPACING="0" CELLPADDING="2" BORDER="0">
<tr>
<td align="left">
<br>
See also:
<a class="eglink" href="/egs/java.util.prefs/pkg.html?l=rel#Events">
Events
</a>
<a class="eglink" href="/egs/java.util.prefs/pkg.html?l=rel#Importing%20and%20Exporting">
Importing and Exporting
</a>
<a class="eglink" href="/egs/java.util.prefs/pkg.html?l=rel#Nodes">
Nodes
</a>
</td>
</tr>
</table>
<br>
<br>
<FONT class="xsmall-font">
© 2002 Addison-Wesley.
</FONT></TD><TD> </TD><TD valign="top"><A href="http://compositesw.com/devzone?ref=javaalmanac"><IMG alt="Click Here" height="600" width="120" border="0" src="/csw_oad_120x600_final.gif"></A></TD>
</TR>
</TABLE>
</BODY>
<HEAD>
<META http-equiv="Content-Type" content="text/html; charset=UTF-8">
<META CONTENT="NO-CACHE" HTTP-EQUIV="PRAGMA">
</HEAD>
</HTML>
⌨️ 快捷键说明
复制代码
Ctrl + C
搜索代码
Ctrl + F
全屏模式
F11
切换主题
Ctrl + Shift + D
显示快捷键
?
增大字号
Ctrl + =
减小字号
Ctrl + -