List of useful environment settings in Java

Question

I've been wondering a long time if there was a comprehensive list of (probably static) methods/fields that store runtime information for the JVM. An incomplete list of examples:

• System.out / System.in
• System.currentTimeMillis()
• System.getProperty()
• System.getConsole()
• Runtime.freeMemory()
• Etc

Does anyone have a link or something?

EDIT: I'm not so dumb as to have not checked the docs for System and Runtime :P I was just wondering if there were other classes where similar methods to determine the state of the machine you're running on are stored.

Answer 1

General Properties

I use this code to get a handle on some of the things known to Java classes that are of particular interest to me.

import java.awt.*; import javax.swing.*; import javax.swing.border.EmptyBorder; import java.util.*;  import java.security.*;  /** A small GUId app. that shows many system and environment properties. Designed to be compatible with Java 1.4+ (hence many requirements like no foreach, no generics, no StringBuilder..). @author Andrew Thompson @version 2008-06-29  */ class SystemProperties {      static String sentence = "The quick brown fox jumped over the lazy dog.";     static String sep = System.getProperty("line.separator");     static String fontText =             sentence +             sep +             sentence.toUpperCase() +             sep +             "0123456789 !@#$%^&*()_+ []\\;',./ {}|:\"<>?";      static String[] convertObjectToSortedStringArray(Object[] unsorted) {         String[] sorted = new String[unsorted.length];         for (int ii = 0; ii < sorted.length; ii++) {             sorted[ii] = (String) unsorted[ii];         }         Arrays.sort(sorted);         return sorted;     }      static String dataPairToTableRow(String property, Object value) {         String val = valueToString(property, value);         return "<tr>" +                 "<th>" +                 "<code>" +                 property +                 "</code>" +                 "</th>" +                 "<td>" +                 val +                 "</td>" +                 "</tr>";     }      static String valueToString(String property, Object value) {         if (value instanceof Color) {             Color color = (Color) value;             String converted =                     "<div style='width: 100%; height: 100%; " +                     "background-color: #" +                     Integer.toHexString(color.getRed()) +                     Integer.toHexString(color.getGreen()) +                     Integer.toHexString(color.getBlue()) +                     ";'>" +                     value.toString() +                     "</div>";             return converted;         } else if (property.toLowerCase().endsWith("path") ||                 property.toLowerCase().endsWith("dirs")) {             return delimitedToHtmlList(                     (String) value,                     System.getProperty("path.separator"));         } else {             return value.toString();         }     }      static String delimitedToHtmlList(String values, String delimiter) {         String[] parts = values.split(delimiter);         StringBuffer sb = new StringBuffer();         sb.append("<ol>");         for (int ii = 0; ii < parts.length; ii++) {             sb.append("<li>");             sb.append(parts[ii]);             sb.append("</li>");         }         return sb.toString();     }      static Component getExampleOfFont(String fontFamily) {         Font font = new Font(fontFamily, Font.PLAIN, 24);         JTextArea ta = new JTextArea();         ta.setFont(font);         ta.setText(fontText);         ta.setEditable(false);         // don't allow these to get focus, as it         // interferes with desired scroll behavior         ta.setFocusable(false);         return ta;     }      static public JScrollPane getOutputWidgetForContent(String content) {         JEditorPane op = new JEditorPane();         op.setContentType("text/html");         op.setEditable(false);          op.setText(content);          return new JScrollPane(op);     }      public static void main(String[] args) {         JTabbedPane tabPane = new JTabbedPane();         StringBuffer sb;         String header = "<html><body><table border=1 width=100%>";          sb = new StringBuffer(header);         Properties prop = System.getProperties();         String[] propStrings = convertObjectToSortedStringArray(                 prop.stringPropertyNames().toArray());         for (int ii = 0; ii < propStrings.length; ii++) {             sb.append(                     dataPairToTableRow(                     propStrings[ii],                     System.getProperty(propStrings[ii])));         }         tabPane.addTab(                 "System",                 getOutputWidgetForContent(sb.toString()));          sb = new StringBuffer(header);         Map environment = System.getenv();         String[] envStrings = convertObjectToSortedStringArray(                 environment.keySet().toArray());         for (int ii = 0; ii < envStrings.length; ii++) {             sb.append(                     dataPairToTableRow(                     envStrings[ii],                     environment.get(envStrings[ii])));         }         tabPane.addTab(                 "Environment",                 getOutputWidgetForContent(sb.toString()));          sb = new StringBuffer(header);         GraphicsEnvironment ge = GraphicsEnvironment.getLocalGraphicsEnvironment();         GraphicsDevice[] gs = ge.getScreenDevices();         for (int j = 0; j < gs.length; j++) {             GraphicsDevice gd = gs[j];             sb.append(                     dataPairToTableRow(                     "Device " + j,                     gd.toString() +                     "  " +                     gd.getIDstring()));             GraphicsConfiguration[] gc =                     gd.getConfigurations();             for (int i = 0; i < gc.length; i++) {                 sb.append(                         dataPairToTableRow(                         "Config " +                         i,                         (int) gc[i].getBounds().getWidth() +                         "x" +                         (int) gc[i].getBounds().getHeight() +                         " " +                         gc[i].getColorModel() +                         ", " +                         "  Accelerated: " +                         gc[i].getImageCapabilities().isAccelerated() +                         "  True Volatile: " +                         gc[i].getImageCapabilities().isTrueVolatile()));             }         }         tabPane.addTab(                 "Graphics Environment",                 getOutputWidgetForContent(sb.toString()));          String[] fonts = ge.getAvailableFontFamilyNames();         JPanel fontTable = new JPanel(new BorderLayout(3, 1));         // to enable key based scrolling in the font panel         fontTable.setFocusable(true);         JPanel fontNameCol = new JPanel(new GridLayout(0, 1, 2, 2));         JPanel fontExampleCol = new JPanel(new GridLayout(0, 1, 2, 2));         fontTable.add(fontNameCol, BorderLayout.WEST);         fontTable.add(fontExampleCol, BorderLayout.CENTER);         for (int ii = 0; ii < fonts.length; ii++) {             fontNameCol.add(new JLabel(fonts[ii]));             fontExampleCol.add(getExampleOfFont(fonts[ii]));         }         tabPane.add("Fonts", new JScrollPane(fontTable));          sb = new StringBuffer(header);          sb.append("<thead>");         sb.append("<tr>");         sb.append("<th>");         sb.append("Code");         sb.append("</th>");         sb.append("<th>");         sb.append("Language");         sb.append("</th>");         sb.append("<th>");         sb.append("Country");         sb.append("</th>");         sb.append("<th>");         sb.append("Variant");         sb.append("</th>");         sb.append("</tr>");         sb.append("</thead>");          Locale[] locales = Locale.getAvailableLocales();         SortableLocale[] sortableLocale = new SortableLocale[locales.length];         for (int ii = 0; ii < locales.length; ii++) {             sortableLocale[ii] = new SortableLocale(locales[ii]);         }         Arrays.sort(sortableLocale);         for (int ii = 0; ii < locales.length; ii++) {             String prefix = "";             String suffix = "";             Locale locale = sortableLocale[ii].getLocale();             if (locale.equals(Locale.getDefault())) {                 prefix = "<b>";                 suffix = "</b>";             }             sb.append(dataPairToTableRow(                     prefix +                     locale.toString() +                     suffix,                     prefix +                     locale.getDisplayLanguage() +                     suffix +                     "</td><td>" +                     prefix +                     locale.getDisplayCountry() +                     suffix +                     "</td><td>" +                     prefix +                     locale.getDisplayVariant() +                     suffix));         }         tabPane.add("Locales",                 getOutputWidgetForContent(sb.toString()));          Locale.getDefault();         int border = 5;         JPanel p = new JPanel(new BorderLayout());         p.setBorder(new EmptyBorder(border, border, border, border));         p.add(tabPane, BorderLayout.CENTER);         p.setPreferredSize(new Dimension(400, 400));         JFrame f = new JFrame("Properties");         f.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);         f.getContentPane().add(p, BorderLayout.CENTER);         f.pack();         f.setMinimumSize(f.getPreferredSize());         f.setSize(600, 500);         f.setLocationRelativeTo(null);         f.setVisible(true);     } }  class SortableLocale implements Comparable {      Locale locale;      SortableLocale(Locale locale) {         this.locale = locale;     }      public String toString() {         return locale.toString();     }      public Locale getLocale() {         return locale;     }      public int compareTo(Object object2) {         SortableLocale locale2 = (SortableLocale) object2;         //Locale locale2 = (Locale)object2;         return locale.toString().compareTo(                 locale2.toString());     } } 

Media

Properties related to synthesized and sampled sound, and images.

/* <applet     code='MediaTypes'     width='900'     height='600'> <param name='show' value='Sound|Sampled|Mixers|Primary Sound Capture Driver'> </applet> */ import javax.imageio.ImageIO; import javax.sound.sampled.*; import javax.sound.midi.*; import java.awt.*; import javax.swing.*; import javax.swing.table.DefaultTableModel; import javax.swing.tree.*; import javax.swing.event.*; import javax.swing.text.Position;  public class MediaTypes extends JApplet {      JTable table;     boolean sortable = false;     JTree tree;      @Override     public void init() {         Runnable r = () -> {             MediaTypes mediaTypes = new MediaTypes();              String show = "";             if (getParameter("show")!=null) {                 show = getParameter("show");             }              JPanel p = new JPanel();             mediaTypes.createGui(p, show);             add(p);             validate();         };         SwingUtilities.invokeLater(r);     }      public static void main(String[] args) {         Runnable r = () -> {             MediaTypes mediaTypes = new MediaTypes();              JPanel p = new JPanel();             mediaTypes.createGui(p);             JOptionPane.showMessageDialog(null,p);         };         SwingUtilities.invokeLater(r);     }      public Object[][] mergeArrays(String name1, Object[] data1, String name2, Object[] data2) {         Object[][] data = new Object[data1.length+data2.length][2];         for (int ii=0; ii<data1.length; ii++) {             data[ii][0] = name1;             data[ii][1] = data1[ii];         }         int offset = data1.length;         for (int ii=offset; ii<data.length; ii++) {             data[ii][0] = name2;             data[ii][1] = data2[ii-offset];         }         return data;     }      public void createGui(JPanel panel) {         createGui(panel, "");     }      public String getShortLineName(String name) {         String[] lineTypes = {             "Clip",             "SourceDataLine",             "TargetDataLine",             "Speaker",             "Microphone",             "Master Volume",             "Line In"         };         for (String shortName : lineTypes) {             if ( name.toLowerCase().replaceAll("_", " ").contains(shortName.toLowerCase() )) {                 return shortName;             }         }         return name;     }      public void createGui(JPanel panel, String path) {          //DefaultMutableTreeNode selected = null;          panel.setLayout( new BorderLayout(5,5) );         final JLabel output = new JLabel("Select a tree leaf to see the details.");         panel.add(output, BorderLayout.SOUTH);          table = new JTable();         try {             table.setAutoCreateRowSorter(true);             sortable = true;         } catch (Throwable ignore) {             // 1.6+ functionality - not vital         }         JScrollPane tableScroll = new JScrollPane(table);         Dimension d = tableScroll.getPreferredSize();         d = new Dimension(450,d.height);         tableScroll.setPreferredSize(d);         panel.add( tableScroll, BorderLayout.CENTER );          DefaultMutableTreeNode rootNode = new DefaultMutableTreeNode("Media");         DefaultTreeModel treeModel = new DefaultTreeModel(rootNode);          DefaultMutableTreeNode imageNode = new DefaultMutableTreeNode("Image");         rootNode.add(imageNode);          Object[][] data;         int offset;         String[] columnNames;          data = mergeArrays(             "Reader",             ImageIO.getReaderFileSuffixes(),             "Writer",             ImageIO.getWriterFileSuffixes() );         columnNames = new String[]{"Input/Output", "Image File Suffixes"};         MediaData md = new MediaData( "Suffixes", columnNames, data);         imageNode.add(new DefaultMutableTreeNode(md));          data = mergeArrays(             "Reader",             ImageIO.getReaderMIMETypes(),             "Writer",             ImageIO.getWriterMIMETypes() );         columnNames = new String[]{"Input/Output", "Image MIME Types"};         md = new MediaData( "MIME", columnNames, data);         imageNode.add(new DefaultMutableTreeNode(md));          DefaultMutableTreeNode soundNode = new DefaultMutableTreeNode("Sound");         rootNode.add(soundNode);          DefaultMutableTreeNode soundSampledNode = new DefaultMutableTreeNode("Sampled");         soundNode.add(soundSampledNode);          md = new MediaData("Suffixes", "Sound File Suffixes", AudioSystem.getAudioFileTypes());         soundSampledNode.add(new DefaultMutableTreeNode(md));          Mixer.Info[] mixerInfo = AudioSystem.getMixerInfo();         String[][] mixerData = new String[mixerInfo.length][4];         for (int ii=0; ii<mixerData.length; ii++) {             mixerData[ii][0] = mixerInfo[ii].getName();             mixerData[ii][1] = mixerInfo[ii].getVendor();             mixerData[ii][2] = mixerInfo[ii].getVersion();             mixerData[ii][3] = mixerInfo[ii].getDescription();         }         columnNames = new String[]{"Name", "Vendor", "Version", "Description"};         md = new MediaData("Mixers", columnNames, mixerData);         DefaultMutableTreeNode soundSampledMixersNode = new DefaultMutableTreeNode(md);         soundSampledNode.add(soundSampledMixersNode);          for (Mixer.Info mixerInfo1 : mixerInfo) {             Mixer mixer = AudioSystem.getMixer(mixerInfo1);             data = mergeArrays(                     "Source",                     mixer.getSourceLineInfo(),                     "Target",                     mixer.getTargetLineInfo() );             columnNames = new String[]{ "Input/Output", "Line Info" };             md = new MediaData(mixerInfo1.getName(), columnNames, data);             DefaultMutableTreeNode soundSampledMixerNode = new DefaultMutableTreeNode(md);             soundSampledMixersNode.add( soundSampledMixerNode );             Line.Info[] source = mixer.getSourceLineInfo();             Line.Info[] target = mixer.getTargetLineInfo();             Line[] all = new Line[source.length + target.length];             try {                 for (int jj=0; jj<source.length; jj++) {                     all[jj] = AudioSystem.getLine(source[jj]);                 }                 for (int jj=source.length; jj<all.length; jj++) {                     all[jj] = AudioSystem.getLine(target[jj-source.length]);                 }                 columnNames = new String[]{"Attribute", "Value"};                 for (Line line : all) {                     Control[] controls = line.getControls();                     if (line instanceof DataLine) {                         DataLine dataLine = (DataLine)line;                         AudioFormat audioFormat = dataLine.getFormat();                         data = new Object[7+controls.length][2];                          data[0][0] = "Channels";                         data[0][1] = audioFormat.getChannels();                          data[1][0] = "Encoding";                         data[1][1] = audioFormat.getEncoding();                          data[2][0] = "Frame Rate";                         data[2][1] = audioFormat.getFrameRate();                          data[3][0] = "Sample Rate";                         data[3][1] = audioFormat.getSampleRate();                          data[4][0] = "Sample Size (bits)";                         data[4][1] = audioFormat.getSampleSizeInBits();                          data[5][0] = "Big Endian";                         data[5][1] = audioFormat.isBigEndian();                          data[6][0] = "Level";                         data[6][1] = dataLine.getLevel();                      } else if (line instanceof Port) {                         Port port = (Port)line;                         Port.Info portInfo = (Port.Info)port.getLineInfo();                         data = new Object[2+controls.length][2];                          data[0][0] = "Name";                         data[0][1] = portInfo.getName();                          data[1][0] = "Source";                         data[1][1] = portInfo.isSource();                     } else {                         System.out.println( "?? " + line );                     }                     int start = data.length-controls.length;                     for (int kk=start; kk<data.length; kk++) {                         data[kk][0] = "Control";                         int index = kk-start;                         data[kk][1] = controls[index];                     }                     md = new MediaData(getShortLineName(line.getLineInfo().toString()), columnNames, data);                     soundSampledMixerNode.add(new DefaultMutableTreeNode(md));                 }             } catch(Exception e) {                 e.printStackTrace();             }         }          int[] midiTypes = MidiSystem.getMidiFileTypes();         data = new Object[midiTypes.length][2];         for (int ii=0; ii<midiTypes.length; ii++) {             data[ii][0] = midiTypes[ii];             String description = "Unknown";             switch (midiTypes[ii]) {                 case 0:                     description = "Single Track";                     break;                 case 1:                     description = "Multi Track";                     break;                 case 2:                     description = "Multi Song";             }             data[ii][1] = description;         }         columnNames = new String[]{"Type", "Description"};         md = new MediaData("MIDI", columnNames, data);         DefaultMutableTreeNode soundMIDINode = new DefaultMutableTreeNode(md);         soundNode.add(soundMIDINode);          columnNames = new String[]{             "Attribute",             "Value"};         MidiDevice.Info[] midiDeviceInfo = MidiSystem.getMidiDeviceInfo() ;         for (MidiDevice.Info midiDeviceInfo1 : midiDeviceInfo) {             data = new Object[6][2];             data[0][0] = "Name";             data[0][1] = midiDeviceInfo1.getName();             data[1][0] = "Vendor";             data[1][1] = midiDeviceInfo1.getVendor();             data[2][0] = "Version";             String version = midiDeviceInfo1.getVersion();             data[2][1] = version.replaceAll("Version ", "");             data[3][0] = "Description";             data[3][1] = midiDeviceInfo1.getDescription();             data[4][0] = "Maximum Transmitters";             data[5][0] = "Maximum Receivers";             try {                 MidiDevice midiDevice = MidiSystem.getMidiDevice(midiDeviceInfo1);                 Object valueTransmitter;                 if (midiDevice.getMaxTransmitters()==AudioSystem.NOT_SPECIFIED) {                     valueTransmitter = "Not specified";                 } else {                     valueTransmitter = midiDevice.getMaxTransmitters();                 }                 Object valueReceiver;                 if (midiDevice.getMaxReceivers()==AudioSystem.NOT_SPECIFIED) {                     valueReceiver = "Not specified";                 } else {                     valueReceiver = midiDevice.getMaxReceivers();                 }                 data[4][1] = valueTransmitter;                 data[5][1] = valueReceiver;             }catch(MidiUnavailableException mue) {                 data[4][1] = "Unknown";                 data[5][1] = "Unknown";             }             md = new MediaData(midiDeviceInfo1.getName(), columnNames, data);             soundMIDINode.add( new DefaultMutableTreeNode(md) );         }          tree = new JTree(treeModel);         tree.setRootVisible(false);         tree.getSelectionModel().setSelectionMode             (TreeSelectionModel.SINGLE_TREE_SELECTION);         tree.addTreeSelectionListener((TreeSelectionEvent tse) -> {             if (sortable) {                 output.setText("Click table column headers to sort.");             }              DefaultMutableTreeNode node = (DefaultMutableTreeNode)                     tree.getLastSelectedPathComponent();              if (node == null) return;              Object nodeInfo = node.getUserObject();             if (nodeInfo instanceof MediaData) {                 MediaData mediaData = (MediaData)nodeInfo;                 table.setModel( new DefaultTableModel(                         mediaData.getData(),                         mediaData.getColumnNames()) );             }         });          for (int ii=0; ii<tree.getRowCount(); ii++) {             tree.expandRow(ii);         }          String[] paths = path.split("\\|");         int row = 0;         TreePath treePath = null;         for (String prefix : paths) {             treePath = tree.getNextMatch( prefix, row, Position.Bias.Forward );             row = tree.getRowForPath(treePath);         }          panel.add(new JScrollPane(tree),BorderLayout.WEST);          tree.setSelectionPath(treePath);         tree.scrollRowToVisible(row);     } }  class MediaData {      String name;     String[] columnNames;     Object[][] data;      MediaData(String name, String columnName, Object[] data) {         this.name = name;          columnNames = new String[1];         columnNames[0] = columnName;          this.data = new Object[data.length][1];         for (int ii=0; ii<data.length; ii++) {             this.data[ii][0] = data[ii];         }     }      MediaData(String name, String[] columnNames, Object[][] data) {         this.name = name;         this.columnNames = columnNames;         this.data = data;     }      @Override     public String toString() {         return name;     }      public String[] getColumnNames() {         return columnNames;     }      public Object[][] getData() {         return data;     } } 

Other

You might also investigate:

• InetAddress
• KeyStore
• Managers
  • CookieManager
  • KeyManagerFactory
  • LogManager