Java by API/java.util.prefs/Preferences

Содержание

1 Preferences: absolutePath()
2 Preferences: addPreferenceChangeListener(PreferenceChangeListener pcl)
3 Preferences: exportNode(OutputStream os)
4 Preferences: exportSubtree(OutputStream os)
5 Preferences: getBoolean(String key, boolean def)
6 Preferences: getByteArray(String key, byte[] def)
7 Preferences: getDouble(String key, double def)
8 Preferences: getFloat(String key, float def)
9 Preferences: getInt(String key, int def)
10 Preferences: getLong(String key, long def)
11 Preferences: get(String key, String def)
12 Preferences: importPreferences(InputStream is)
13 Preferences: keys()
14 Preferences.MAX_KEY_LENGTH
15 Preferences.MAX_VALUE_LENGTH
16 Preferences: name()
17 Preferences: nodeExists(String pathName)
18 Preferences: node(String pathName)
19 Preferences: parent()
20 Preferences: putBoolean(String key, boolean value)
21 Preferences: putByteArray(String key, byte[] value)
22 Preferences: putDouble(String key, double value)
23 Preferences: putFloat(String key, float value)
24 Preferences: putLong(String key, long value)
25 Preferences: put(String key, String value)
26 Preferences: removeNode()
27 Preferences: remove(String key)
28 Preferences: systemRoot()
29 Preferences: userNodeForPackage(Class c)
30 Preferences: userRoot()

Preferences: absolutePath()

   <source lang="java">

import java.util.prefs.Preferences; public class Main {

 public static void main(String args[]) throws Exception {
   Preferences prefsRoot = Preferences.userRoot();
   Preferences myPrefs = prefsRoot.node("PreferenceExample");
   myPrefs.put("A", "a");
   myPrefs.put("B", "b");
   myPrefs.put("C", "c");
   System.out.println("Node"s absolute path: " + myPrefs.absolutePath());
 }

}

 </source>

Preferences: addPreferenceChangeListener(PreferenceChangeListener pcl)

   <source lang="java">

import java.util.prefs.PreferenceChangeEvent; import java.util.prefs.PreferenceChangeListener; import java.util.prefs.Preferences; public class Main implements PreferenceChangeListener {

 private Preferences userPrefs;
 public static final String NAMEPREF = "name";
 public static final String EMAILPREF = "email";
 public static void main(String args[]) {
   new Main();
 }
 public Main() {
   userPrefs = Preferences.userNodeForPackage(Main.class);
   System.out.println(userPrefs.get(NAMEPREF, ""));
   System.out.println(userPrefs.get(EMAILPREF, ""));
   userPrefs.put(NAMEPREF, "name");
   userPrefs.put(EMAILPREF, "email");
   Preferences.userNodeForPackage(Main.class).addPreferenceChangeListener(this);
 }
 public void preferenceChange(PreferenceChangeEvent evt) {
   String key = evt.getKey();
   String val = evt.getNewValue();
   if (key.equals(NAMEPREF)) {
     System.out.println(val);
   } else if (key.equals(EMAILPREF)) {
     System.out.println(val);
   }
 }

}

 </source>

Preferences: exportNode(OutputStream os)

   <source lang="java">

import java.io.FileOutputStream; import java.util.prefs.Preferences; public class Main {

 public static void main(String[] argv) throws Exception {
   Preferences prefs = Preferences.userNodeForPackage(String.class);
   // Save some values
   prefs.put("myString", "a string"); // String
   prefs.putBoolean("myBoolean", true); // boolean
   prefs.putInt("myInt", 123); // int
   prefs.putLong("myLong", 123L); // long
   prefs.putFloat("myFloat", 12.3F); // float
   prefs.putDouble("myDouble", 12.3); // double
   byte[] bytes = new byte[10];
   prefs.putByteArray("myByteArray", bytes); // byte[]
   // Export the node to a file
   prefs.exportNode(new FileOutputStream("output.xml"));
 }

}

 </source>

Preferences: exportSubtree(OutputStream os)

   <source lang="java">

import java.io.FileOutputStream; import java.util.prefs.Preferences; public class Main {

 public static void main(String args[]) throws Exception {
   Preferences prefsRoot = Preferences.userRoot();
   Preferences myPrefs = prefsRoot.node("PreferenceExample");
   myPrefs.put("A", "a");
   myPrefs.put("B", "b");
   myPrefs.put("C", "c");
   FileOutputStream fos = new FileOutputStream("prefs.xml");
   myPrefs.exportSubtree(fos);
   fos.close();
 }

}

 </source>

Preferences: getBoolean(String key, boolean def)

   <source lang="java">

import java.util.prefs.Preferences; public class Main {

 public static void main(String[] argv) throws Exception {
   Preferences prefs = Preferences.userNodeForPackage(Main.class);
   // Preference key name
   final String PREF_NAME = "name_of_preference";
   // Save
   prefs.put(PREF_NAME, "a string"); // String
   prefs.putBoolean(PREF_NAME, true); // boolean
   prefs.putInt(PREF_NAME, 123); // int
   prefs.putLong(PREF_NAME, 123L); // long
   prefs.putFloat(PREF_NAME, 12.3F); // float
   prefs.putDouble(PREF_NAME, 12.3); // double
   byte[] bytes = new byte[1024];
   prefs.putByteArray(PREF_NAME, bytes); // byte[]
   // Retrieve
   String s = prefs.get(PREF_NAME, "a string"); // String
   boolean b = prefs.getBoolean(PREF_NAME, true); // boolean
   int i = prefs.getInt(PREF_NAME, 123); // int
   long l = prefs.getLong(PREF_NAME, 123L); // long
   float f = prefs.getFloat(PREF_NAME, 12.3F); // float
   double d = prefs.getDouble(PREF_NAME, 12.3); // double
   bytes = prefs.getByteArray(PREF_NAME, bytes); // byte[]
 }

}

 </source>

Preferences: getByteArray(String key, byte[] def)

   <source lang="java">

import java.util.prefs.Preferences; public class Main {

 public static void main(String[] argv) throws Exception {
   Preferences prefs = Preferences.userNodeForPackage(Main.class);
   // Preference key name
   final String PREF_NAME = "name_of_preference";
   // Save
   prefs.put(PREF_NAME, "a string"); // String
   prefs.putBoolean(PREF_NAME, true); // boolean
   prefs.putInt(PREF_NAME, 123); // int
   prefs.putLong(PREF_NAME, 123L); // long
   prefs.putFloat(PREF_NAME, 12.3F); // float
   prefs.putDouble(PREF_NAME, 12.3); // double
   byte[] bytes = new byte[1024];
   prefs.putByteArray(PREF_NAME, bytes); // byte[]
   // Retrieve
   String s = prefs.get(PREF_NAME, "a string"); // String
   boolean b = prefs.getBoolean(PREF_NAME, true); // boolean
   int i = prefs.getInt(PREF_NAME, 123); // int
   long l = prefs.getLong(PREF_NAME, 123L); // long
   float f = prefs.getFloat(PREF_NAME, 12.3F); // float
   double d = prefs.getDouble(PREF_NAME, 12.3); // double
   bytes = prefs.getByteArray(PREF_NAME, bytes); // byte[]
 }

}

 </source>

Preferences: getDouble(String key, double def)

   <source lang="java">

import java.util.prefs.Preferences; public class Main {

 public static void main(String[] argv) throws Exception {
   Preferences prefs = Preferences.userNodeForPackage(Main.class);
   // Preference key name
   final String PREF_NAME = "name_of_preference";
   // Save
   prefs.put(PREF_NAME, "a string"); // String
   prefs.putBoolean(PREF_NAME, true); // boolean
   prefs.putInt(PREF_NAME, 123); // int
   prefs.putLong(PREF_NAME, 123L); // long
   prefs.putFloat(PREF_NAME, 12.3F); // float
   prefs.putDouble(PREF_NAME, 12.3); // double
   byte[] bytes = new byte[1024];
   prefs.putByteArray(PREF_NAME, bytes); // byte[]
   // Retrieve
   String s = prefs.get(PREF_NAME, "a string"); // String
   boolean b = prefs.getBoolean(PREF_NAME, true); // boolean
   int i = prefs.getInt(PREF_NAME, 123); // int
   long l = prefs.getLong(PREF_NAME, 123L); // long
   float f = prefs.getFloat(PREF_NAME, 12.3F); // float
   double d = prefs.getDouble(PREF_NAME, 12.3); // double
   bytes = prefs.getByteArray(PREF_NAME, bytes); // byte[]
 }

}

 </source>

Preferences: getFloat(String key, float def)

   <source lang="java">

import java.util.prefs.Preferences; public class Main {

 public static void main(String[] argv) throws Exception {
   Preferences prefs = Preferences.userNodeForPackage(Main.class);
   // Preference key name
   final String PREF_NAME = "name_of_preference";
   // Save
   prefs.put(PREF_NAME, "a string"); // String
   prefs.putBoolean(PREF_NAME, true); // boolean
   prefs.putInt(PREF_NAME, 123); // int
   prefs.putLong(PREF_NAME, 123L); // long
   prefs.putFloat(PREF_NAME, 12.3F); // float
   prefs.putDouble(PREF_NAME, 12.3); // double
   byte[] bytes = new byte[1024];
   prefs.putByteArray(PREF_NAME, bytes); // byte[]
   // Retrieve
   String s = prefs.get(PREF_NAME, "a string"); // String
   boolean b = prefs.getBoolean(PREF_NAME, true); // boolean
   int i = prefs.getInt(PREF_NAME, 123); // int
   long l = prefs.getLong(PREF_NAME, 123L); // long
   float f = prefs.getFloat(PREF_NAME, 12.3F); // float
   double d = prefs.getDouble(PREF_NAME, 12.3); // double
   bytes = prefs.getByteArray(PREF_NAME, bytes); // byte[]
 }

}

 </source>

Preferences: getInt(String key, int def)

   <source lang="java">

import java.util.prefs.Preferences; public class Main {

 public static void main(String[] argv) throws Exception {
   Preferences prefs = Preferences.userNodeForPackage(Main.class);
   // Preference key name
   final String PREF_NAME = "name_of_preference";
   // Save
   prefs.put(PREF_NAME, "a string"); // String
   prefs.putBoolean(PREF_NAME, true); // boolean
   prefs.putInt(PREF_NAME, 123); // int
   prefs.putLong(PREF_NAME, 123L); // long
   prefs.putFloat(PREF_NAME, 12.3F); // float
   prefs.putDouble(PREF_NAME, 12.3); // double
   byte[] bytes = new byte[1024];
   prefs.putByteArray(PREF_NAME, bytes); // byte[]
   // Retrieve
   String s = prefs.get(PREF_NAME, "a string"); // String
   boolean b = prefs.getBoolean(PREF_NAME, true); // boolean
   int i = prefs.getInt(PREF_NAME, 123); // int
   long l = prefs.getLong(PREF_NAME, 123L); // long
   float f = prefs.getFloat(PREF_NAME, 12.3F); // float
   double d = prefs.getDouble(PREF_NAME, 12.3); // double
   bytes = prefs.getByteArray(PREF_NAME, bytes); // byte[]
 }

}

 </source>

Preferences: getLong(String key, long def)

   <source lang="java">

import java.util.prefs.Preferences; public class Main {

 public static void main(String[] argv) throws Exception {
   Preferences prefs = Preferences.userNodeForPackage(Main.class);
   // Preference key name
   final String PREF_NAME = "name_of_preference";
   // Save
   prefs.put(PREF_NAME, "a string"); // String
   prefs.putBoolean(PREF_NAME, true); // boolean
   prefs.putInt(PREF_NAME, 123); // int
   prefs.putLong(PREF_NAME, 123L); // long
   prefs.putFloat(PREF_NAME, 12.3F); // float
   prefs.putDouble(PREF_NAME, 12.3); // double
   byte[] bytes = new byte[1024];
   prefs.putByteArray(PREF_NAME, bytes); // byte[]
   // Retrieve
   String s = prefs.get(PREF_NAME, "a string"); // String
   boolean b = prefs.getBoolean(PREF_NAME, true); // boolean
   int i = prefs.getInt(PREF_NAME, 123); // int
   long l = prefs.getLong(PREF_NAME, 123L); // long
   float f = prefs.getFloat(PREF_NAME, 12.3F); // float
   double d = prefs.getDouble(PREF_NAME, 12.3); // double
   bytes = prefs.getByteArray(PREF_NAME, bytes); // byte[]
 }

}

 </source>

Preferences: get(String key, String def)

   <source lang="java">

import java.util.prefs.Preferences; public class MainClass {

 public static void main(String[] args) {
   // Setup the Preferences for this application, by class.
   Preferences prefs = Preferences.userNodeForPackage(MainClass.class);
   // Retrieve some preferences previously stored, with defaults in case
   // this is the first run.
   String text = prefs.get("A", "a");
   String display = prefs.get("B", "b");
   System.out.println(text);
   System.out.println(display);
   // Assume the user chose new preference values: Store them back.
   prefs.put("A", "aa");
   prefs.put("B", "bb");
 }

}

 </source>

Preferences: importPreferences(InputStream is)

   <source lang="java">

import java.io.BufferedInputStream; import java.io.FileInputStream; import java.io.InputStream; import java.util.prefs.Preferences; public class Main {

 public static void main(String[] argv) throws Exception {
   // Create an input stream on a file
   InputStream is = new BufferedInputStream(new FileInputStream("output.xml"));
   // Import preference data
   Preferences.importPreferences(is);
 }

}

 </source>

Preferences: keys()

   <source lang="java">

import java.util.prefs.Preferences; public class Main {

 public static void main(String args[]) throws Exception {
   Preferences prefsRoot = Preferences.userRoot();
   Preferences myPrefs = prefsRoot.node("PreferenceExample");
   myPrefs.put("A", "a");
   myPrefs.put("B", "b");
   myPrefs.put("C", "c");
   System.out.print("Node"s keys: ");
   for (String s : myPrefs.keys()) {
     System.out.print(s + "");
   }
 }

}

 </source>

Preferences.MAX_KEY_LENGTH

   <source lang="java">

import java.util.prefs.Preferences; public class Main {

 public static void main(String[] argv) throws Exception {
   // Get maximum key length
   int keyMax = Preferences.MAX_KEY_LENGTH;
   // Get maximum value length
   int valueMax = Preferences.MAX_VALUE_LENGTH;
   // Get maximum length of byte array values
   int bytesMax = Preferences.MAX_VALUE_LENGTH * 3 / 4;
 }

}

 </source>

Preferences.MAX_VALUE_LENGTH

   <source lang="java">

import java.util.prefs.Preferences; public class Main {

 public static void main(String[] argv) throws Exception {
   // Get maximum key length
   int keyMax = Preferences.MAX_KEY_LENGTH;
   // Get maximum value length
   int valueMax = Preferences.MAX_VALUE_LENGTH;
   // Get maximum length of byte array values
   int bytesMax = Preferences.MAX_VALUE_LENGTH * 3 / 4;
 }

}

 </source>

Preferences: name()

   <source lang="java">

import java.util.prefs.Preferences; public class Main {

 public static void main(String args[]) throws Exception {
   Preferences prefsRoot = Preferences.userRoot();
   Preferences myPrefs = prefsRoot.node("PreferenceExample");
   myPrefs.put("A", "a");
   myPrefs.put("B", "b");
   myPrefs.put("C", "c");
   System.out.println("Node"s name: " + myPrefs.name());
   System.out.println("Node"s parent: " + myPrefs.parent());
   System.out.println("NODE: " + myPrefs);
 }

}

 </source>

Preferences: nodeExists(String pathName)

   <source lang="java">

import java.util.prefs.Preferences; public class Main {

 public static void main(String[] argv) throws Exception {
   boolean exists = Preferences.userRoot().nodeExists("/yourValue"); 
   if (!exists) {
     Preferences prefs = Preferences.userRoot().node("/yourValue");
     prefs.removeNode();
     // prefs.removeNode();
   }
   Preferences prefs = Preferences.userRoot().node("/yourValue/child");
   exists = Preferences.userRoot().nodeExists("/yourValue"); 
   exists = Preferences.userRoot().nodeExists("/yourValue/child"); 
   Preferences.userRoot().node("/yourValue").removeNode();
   exists = Preferences.userRoot().nodeExists("/yourValue"); 
   exists = Preferences.userRoot().nodeExists("/yourValue/child"); 
 }

}

 </source>

Preferences: node(String pathName)

   <source lang="java">

import java.util.prefs.Preferences; public class Main {

 public static void main(String args[]) throws Exception {
   Preferences prefsRoot = Preferences.userRoot();
   Preferences myPrefs = prefsRoot.node("PreferenceExample");
   myPrefs.put("A", "a");
   myPrefs.put("B", "b");
   myPrefs.put("C", "c");
   System.out.println("Node"s absolute path: " + myPrefs.absolutePath());
 }

}

 </source>

Preferences: parent()

   <source lang="java">

import java.util.prefs.Preferences; public class Main {

 public static void main(String args[]) throws Exception {
   Preferences prefsRoot = Preferences.userRoot();
   Preferences myPrefs = prefsRoot.node("PreferenceExample");
   myPrefs.put("A", "a");
   myPrefs.put("B", "b");
   myPrefs.put("C", "c");
   System.out.println("Node"s name: " + myPrefs.name());
   System.out.println("Node"s parent: " + myPrefs.parent());
   System.out.println("NODE: " + myPrefs);
 }

}

 </source>

Preferences: putBoolean(String key, boolean value)

   <source lang="java">

import java.util.prefs.Preferences; public class Main {

 public static void main(String[] argv) throws Exception {
   Preferences prefs = Preferences.userNodeForPackage(Main.class);
   // Preference key name
   final String PREF_NAME = "name_of_preference";
   // Save
   prefs.put(PREF_NAME, "a string"); // String
   prefs.putBoolean(PREF_NAME, true); // boolean
   prefs.putInt(PREF_NAME, 123); // int
   prefs.putLong(PREF_NAME, 123L); // long
   prefs.putFloat(PREF_NAME, 12.3F); // float
   prefs.putDouble(PREF_NAME, 12.3); // double
   byte[] bytes = new byte[1024];
   prefs.putByteArray(PREF_NAME, bytes); // byte[]
   // Retrieve
   String s = prefs.get(PREF_NAME, "a string"); // String
   boolean b = prefs.getBoolean(PREF_NAME, true); // boolean
   int i = prefs.getInt(PREF_NAME, 123); // int
   long l = prefs.getLong(PREF_NAME, 123L); // long
   float f = prefs.getFloat(PREF_NAME, 12.3F); // float
   double d = prefs.getDouble(PREF_NAME, 12.3); // double
   bytes = prefs.getByteArray(PREF_NAME, bytes); // byte[]
 }

}

 </source>

Preferences: putByteArray(String key, byte[] value)

   <source lang="java">

import java.util.prefs.Preferences; public class Main {

 public static void main(String[] argv) throws Exception {
   Preferences prefs = Preferences.userNodeForPackage(Main.class);
   // Preference key name
   final String PREF_NAME = "name_of_preference";
   // Save
   prefs.put(PREF_NAME, "a string"); // String
   prefs.putBoolean(PREF_NAME, true); // boolean
   prefs.putInt(PREF_NAME, 123); // int
   prefs.putLong(PREF_NAME, 123L); // long
   prefs.putFloat(PREF_NAME, 12.3F); // float
   prefs.putDouble(PREF_NAME, 12.3); // double
   byte[] bytes = new byte[1024];
   prefs.putByteArray(PREF_NAME, bytes); // byte[]
   // Retrieve
   String s = prefs.get(PREF_NAME, "a string"); // String
   boolean b = prefs.getBoolean(PREF_NAME, true); // boolean
   int i = prefs.getInt(PREF_NAME, 123); // int
   long l = prefs.getLong(PREF_NAME, 123L); // long
   float f = prefs.getFloat(PREF_NAME, 12.3F); // float
   double d = prefs.getDouble(PREF_NAME, 12.3); // double
   bytes = prefs.getByteArray(PREF_NAME, bytes); // byte[]
 }

}

 </source>

Preferences: putDouble(String key, double value)

   <source lang="java">

import java.util.prefs.Preferences; public class Main {

 public static void main(String[] argv) throws Exception {
   Preferences prefs = Preferences.userNodeForPackage(Main.class);
   // Preference key name
   final String PREF_NAME = "name_of_preference";
   // Save
   prefs.put(PREF_NAME, "a string"); // String
   prefs.putBoolean(PREF_NAME, true); // boolean
   prefs.putInt(PREF_NAME, 123); // int
   prefs.putLong(PREF_NAME, 123L); // long
   prefs.putFloat(PREF_NAME, 12.3F); // float
   prefs.putDouble(PREF_NAME, 12.3); // double
   byte[] bytes = new byte[1024];
   prefs.putByteArray(PREF_NAME, bytes); // byte[]
   // Retrieve
   String s = prefs.get(PREF_NAME, "a string"); // String
   boolean b = prefs.getBoolean(PREF_NAME, true); // boolean
   int i = prefs.getInt(PREF_NAME, 123); // int
   long l = prefs.getLong(PREF_NAME, 123L); // long
   float f = prefs.getFloat(PREF_NAME, 12.3F); // float
   double d = prefs.getDouble(PREF_NAME, 12.3); // double
   bytes = prefs.getByteArray(PREF_NAME, bytes); // byte[]
 }

}

 </source>

Preferences: putFloat(String key, float value)

   <source lang="java">

import java.util.prefs.Preferences; public class Main {

 public static void main(String[] argv) throws Exception {
   Preferences prefs = Preferences.userNodeForPackage(Main.class);
   // Preference key name
   final String PREF_NAME = "name_of_preference";
   // Save
   prefs.put(PREF_NAME, "a string"); // String
   prefs.putBoolean(PREF_NAME, true); // boolean
   prefs.putInt(PREF_NAME, 123); // int
   prefs.putLong(PREF_NAME, 123L); // long
   prefs.putFloat(PREF_NAME, 12.3F); // float
   prefs.putDouble(PREF_NAME, 12.3); // double
   byte[] bytes = new byte[1024];
   prefs.putByteArray(PREF_NAME, bytes); // byte[]
   // Retrieve
   String s = prefs.get(PREF_NAME, "a string"); // String
   boolean b = prefs.getBoolean(PREF_NAME, true); // boolean
   int i = prefs.getInt(PREF_NAME, 123); // int
   long l = prefs.getLong(PREF_NAME, 123L); // long
   float f = prefs.getFloat(PREF_NAME, 12.3F); // float
   double d = prefs.getDouble(PREF_NAME, 12.3); // double
   bytes = prefs.getByteArray(PREF_NAME, bytes); // byte[]
 }

}

 </source>

Preferences: putLong(String key, long value)

   <source lang="java">

import java.util.prefs.Preferences; public class Main {

 public static void main(String[] argv) throws Exception {
   Preferences prefs = Preferences.userNodeForPackage(Main.class);
   // Preference key name
   final String PREF_NAME = "name_of_preference";
   // Save
   prefs.put(PREF_NAME, "a string"); // String
   prefs.putBoolean(PREF_NAME, true); // boolean
   prefs.putInt(PREF_NAME, 123); // int
   prefs.putLong(PREF_NAME, 123L); // long
   prefs.putFloat(PREF_NAME, 12.3F); // float
   prefs.putDouble(PREF_NAME, 12.3); // double
   byte[] bytes = new byte[1024];
   prefs.putByteArray(PREF_NAME, bytes); // byte[]
   // Retrieve
   String s = prefs.get(PREF_NAME, "a string"); // String
   boolean b = prefs.getBoolean(PREF_NAME, true); // boolean
   int i = prefs.getInt(PREF_NAME, 123); // int
   long l = prefs.getLong(PREF_NAME, 123L); // long
   float f = prefs.getFloat(PREF_NAME, 12.3F); // float
   double d = prefs.getDouble(PREF_NAME, 12.3); // double
   bytes = prefs.getByteArray(PREF_NAME, bytes); // byte[]
 }

}

 </source>

Preferences: put(String key, String value)

   <source lang="java">

import java.util.prefs.Preferences; public class MainClass {

 public static void main(String[] args) {
   // Setup the Preferences for this application, by class.
   Preferences prefs = Preferences.userNodeForPackage(MainClass.class);
   // Retrieve some preferences previously stored, with defaults in case
   // this is the first run.
   String text = prefs.get("A", "a");
   String display = prefs.get("B", "b");
   System.out.println(text);
   System.out.println(display);
   // Assume the user chose new preference values: Store them back.
   prefs.put("A", "aa");
   prefs.put("B", "bb");
 }

}

 </source>

Preferences: removeNode()

   <source lang="java">

import java.util.prefs.Preferences; public class Main {

 public static void main(String[] argv) throws Exception {
   boolean exists = Preferences.userRoot().nodeExists("/yourValue"); 
   if (!exists) {
     Preferences prefs = Preferences.userRoot().node("/yourValue");
     prefs.removeNode();
     // prefs.removeNode();
   }
   Preferences prefs = Preferences.userRoot().node("/yourValue/child");
   exists = Preferences.userRoot().nodeExists("/yourValue"); 
   exists = Preferences.userRoot().nodeExists("/yourValue/child"); 
   Preferences.userRoot().node("/yourValue").removeNode();
   exists = Preferences.userRoot().nodeExists("/yourValue"); 
   exists = Preferences.userRoot().nodeExists("/yourValue/child"); 
 }

}

 </source>

Preferences: remove(String key)

   <source lang="java">

import java.util.prefs.Preferences; public class Main {

 public static void main(String[] argv) throws Exception {
   // Get the user preference node for java.lang
   Preferences prefs = Preferences.userNodeForPackage(String.class);
   // Remove a preference in the node
   final String PREF_NAME = "name_of_preference";
   prefs.remove(PREF_NAME);
   // Remove all preferences in the node
   prefs.clear();
 }

}

 </source>

Preferences: systemRoot()

   <source lang="java">

import java.util.prefs.Preferences; public class Main {

 public static void main(String[] argv) throws Exception {
   // System preference nodes
   // Use a Class
   Preferences prefs = Preferences.systemNodeForPackage(java.lang.String.class);
   // Use an absolute path
   prefs = Preferences.systemRoot().node("/java/lang/String");
   // Use a relative path
   prefs = Preferences.systemRoot().node("/javax/swing");
   prefs = prefs.node("text/html");
   // User preference nodes
   // Use a class
   prefs = Preferences.userNodeForPackage(Main.class);
   // Use an absolute path
   prefs = Preferences.userRoot().node("/com/mycompany");
   // Use a relative path
   prefs = Preferences.userRoot().node("/javax/swing");
   prefs = prefs.node("text/html");
 }

}

 </source>

Preferences: userNodeForPackage(Class c)

   <source lang="java">

import java.util.prefs.Preferences; public class MainClass {

 public static void main(String[] args) {
   // Setup the Preferences for this application, by class.
   Preferences prefs = Preferences.userNodeForPackage(MainClass.class);
   // Retrieve some preferences previously stored, with defaults in case
   // this is the first run.
   String text = prefs.get("A", "a");
   String display = prefs.get("B", "b");
   System.out.println(text);
   System.out.println(display);
   // Assume the user chose new preference values: Store them back.
   prefs.put("A", "aa");
   prefs.put("B", "bb");
 }

}

 </source>

Preferences: userRoot()

   <source lang="java">

import java.util.prefs.Preferences; public class Main {

 public static void main(String args[]) throws Exception {
   Preferences prefsRoot = Preferences.userRoot();
   Preferences myPrefs = prefsRoot.node("PreferenceExample");
   myPrefs.put("A", "a");
   myPrefs.put("B", "b");
   myPrefs.put("C", "c");
   System.out.println("Node"s absolute path: " + myPrefs.absolutePath());
 }

}

 </source>

Java by API/java.util.prefs/Preferences

Содержание

Preferences: absolutePath()

Preferences: addPreferenceChangeListener(PreferenceChangeListener pcl)

Preferences: exportNode(OutputStream os)

Preferences: exportSubtree(OutputStream os)

Preferences: getBoolean(String key, boolean def)

Preferences: getByteArray(String key, byte[] def)

Preferences: getDouble(String key, double def)

Preferences: getFloat(String key, float def)

Preferences: getInt(String key, int def)

Preferences: getLong(String key, long def)

Preferences: get(String key, String def)

Preferences: importPreferences(InputStream is)

Preferences: keys()

Preferences.MAX_KEY_LENGTH

Preferences.MAX_VALUE_LENGTH

Preferences: name()

Preferences: nodeExists(String pathName)

Preferences: node(String pathName)

Preferences: parent()

Preferences: putBoolean(String key, boolean value)

Preferences: putByteArray(String key, byte[] value)

Preferences: putDouble(String key, double value)

Preferences: putFloat(String key, float value)

Preferences: putLong(String key, long value)

Preferences: put(String key, String value)

Preferences: removeNode()

Preferences: remove(String key)

Preferences: systemRoot()

Preferences: userNodeForPackage(Class c)

Preferences: userRoot()

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