FileDocCategorySizeDatePackage
ImmutableDescriptor.javaAPI DocJava SE 6 API21327Tue Jun 10 00:26:12 BST 2008javax.management

ImmutableDescriptor

public class ImmutableDescriptor extends Object implements Descriptor
An immutable descriptor.
since
1.6

Fields Summary
private static final long
serialVersionUID
private final String[]
names
The names of the fields in this ImmutableDescriptor with their original case. The names must be in alphabetical order as determined by {@link String#CASE_INSENSITIVE_ORDER}.
private final Object[]
values
The values of the fields in this ImmutableDescriptor. The elements in this array match the corresponding elements in the {@code names} array.
private transient int
hashCode
public static final ImmutableDescriptor
EMPTY_DESCRIPTOR
An empty descriptor.
Constructors Summary
public ImmutableDescriptor(String[] fieldNames, Object[] fieldValues)
Construct a descriptor containing the given fields and values.

throws
IllegalArgumentException if either array is null, or if the arrays have different sizes, or if a field name is null or empty, or if the same field name appears more than once.

    
                                                   
         
        this(makeMap(fieldNames, fieldValues));
    
public ImmutableDescriptor(String fields)
Construct a descriptor containing the given fields. Each String must be of the form {@code fieldName=fieldValue}. The field name ends at the first {@code =} character; for example if the String is {@code a=b=c} then the field name is {@code a} and its value is {@code b=c}.

throws
IllegalArgumentException if the parameter is null, or if a field name is empty, or if the same field name appears more than once, or if one of the strings does not contain an {@code =} character.

        this(makeMap(fields));
    
public ImmutableDescriptor(Map fields)

Construct a descriptor where the names and values of the fields are the keys and values of the given Map.

throws
IllegalArgumentException if the parameter is null, or if a field name is null or empty, or if the same field name appears more than once (which can happen because field names are not case sensitive).

        if (fields == null)
            throw new IllegalArgumentException("Null Map");
        SortedMap<String, Object> map =
                new TreeMap<String, Object>(String.CASE_INSENSITIVE_ORDER);
        for (Map.Entry<String, ?> entry : fields.entrySet()) {
            String name = entry.getKey();
            if (name == null || name.equals(""))
                throw new IllegalArgumentException("Empty or null field name");
            if (map.containsKey(name))
                throw new IllegalArgumentException("Duplicate name: " + name);
            map.put(name, entry.getValue());
        }
        int size = map.size();
        this.names = map.keySet().toArray(new String[size]);
        this.values = map.values().toArray(new Object[size]);
    
Methods Summary
private static voidcheckIllegalFieldName(java.lang.String name)

        if (name == null || name.equals(""))
            illegal("Null or empty field name");
    
public javax.management.Descriptorclone()

Returns a descriptor which is equal to this descriptor. Changes to the returned descriptor will have no effect on this descriptor, and vice versa.

This method returns the object on which it is called. A subclass can override it to return another object provided the contract is respected.

exception
RuntimeOperationsException for illegal value for field Names or field Values. If the descriptor construction fails for any reason, this exception will be thrown.

        return this;
    
public booleanequals(java.lang.Object o)
Compares this descriptor to the given object. The objects are equal if the given object is also a Descriptor, and if the two Descriptors have the same field names (possibly differing in case) and the same associated values. The respective values for a field in the two Descriptors are equal if the following conditions hold:

  • If one value is null then the other must be too.
  • If one value is a primitive array then the other must be a primitive array of the same type with the same elements.
  • If one value is an object array then the other must be too and {@link Arrays#deepEquals(Object[],Object[])} must return true.
  • Otherwise {@link Object#equals(Object)} must return true.

param
o the object to compare with.
return
{@code true} if the objects are the same; {@code false} otherwise.

        if (o == this)
            return true;
        if (!(o instanceof Descriptor))
            return false;
        String[] onames;
        if (o instanceof ImmutableDescriptor) {
            onames = ((ImmutableDescriptor) o).names;
        } else {
            onames = ((Descriptor) o).getFieldNames();
            Arrays.sort(onames, String.CASE_INSENSITIVE_ORDER);
        }
        if (names.length != onames.length)
            return false;
        for (int i = 0; i < names.length; i++) {
            if (!names[i].equalsIgnoreCase(onames[i]))
                return false;
        }
        Object[] ovalues;
        if (o instanceof ImmutableDescriptor)
            ovalues = ((ImmutableDescriptor) o).values;
        else
            ovalues = ((Descriptor) o).getFieldValues(onames);
        return Arrays.deepEquals(values, ovalues);
    
private intfieldIndex(java.lang.String name)

        return Arrays.binarySearch(names, name, String.CASE_INSENSITIVE_ORDER);
    
private static intfindNonEmpty(javax.management.Descriptor[] ds, int start)

        for (int i = start; i < ds.length; i++) {
            if (!isEmpty(ds[i]))
                return i;
        }
        return -1;
    
public final java.lang.String[]getFieldNames()

        return names.clone();
    
public final java.lang.ObjectgetFieldValue(java.lang.String fieldName)

        checkIllegalFieldName(fieldName);
        int i = fieldIndex(fieldName);
        if (i < 0)
            return null;
        Object v = values[i];
        if (v == null || !v.getClass().isArray())
            return v;
        if (v instanceof Object[])
            return ((Object[]) v).clone();
        // clone the primitive array, could use an 8-way if/else here
        int len = Array.getLength(v);
        Object a = Array.newInstance(v.getClass().getComponentType(), len);
        System.arraycopy(v, 0, a, 0, len);
        return a;
    
public final java.lang.Object[]getFieldValues(java.lang.String fieldNames)

        if (fieldNames == null)
            return values.clone();
        Object[] result = new Object[fieldNames.length];
        for (int i = 0; i < fieldNames.length; i++) {
            String name = fieldNames[i];
            if (name != null && !name.equals(""))
                result[i] = getFieldValue(name);
        }
        return result;
    
public final java.lang.String[]getFields()

        String[] result = new String[names.length];
        for (int i = 0; i < result.length; i++) {
            Object value = values[i];
            if (value == null)
                value = "";
            else if (!(value instanceof String))
                value = "(" + value + ")";
            result[i] = names[i] + "=" + value;
        }
        return result;
    
public inthashCode()

Returns the hash code value for this descriptor. The hash code is computed as the sum of the hash codes for each field in the descriptor. The hash code of a field with name {@code n} and value {@code v} is {@code n.toLowerCase().hashCode() ^ h}. Here {@code h} is the hash code of {@code v}, computed as follows:

  • If {@code v} is null then {@code h} is 0.
  • If {@code v} is a primitive array then {@code h} is computed using the appropriate overloading of {@code java.util.Arrays.hashCode}.
  • If {@code v} is an object array then {@code h} is computed using {@link Arrays#deepHashCode(Object[])}.
  • Otherwise {@code h} is {@code v.hashCode()}.

return
A hash code value for this object.

        if (hashCode == -1) {
            int hash = 0;
            for (int i = 0; i < names.length; i++) {
                Object v = values[i];
                int h;
                if (v == null)
                    h = 0;
                else if (v instanceof Object[])
                    h = Arrays.deepHashCode((Object[]) v);
                else if (v.getClass().isArray()) {
                    h = Arrays.deepHashCode(new Object[] {v}) - 31;
                    // hashcode of a list containing just v is
                    // v.hashCode() + 31, see List.hashCode()
                } else
                    h = v.hashCode();
                hash += names[i].toLowerCase().hashCode() ^ h;
            }
            hashCode = hash;
        }
        return hashCode;
    
private static voidillegal(java.lang.String message)

        IllegalArgumentException iae = new IllegalArgumentException(message);
        throw new RuntimeOperationsException(iae);
    
private static booleanisEmpty(javax.management.Descriptor d)

        if (d == null)
            return true;
        else if (d instanceof ImmutableDescriptor)
            return ((ImmutableDescriptor) d).names.length == 0;
        else
            return (d.getFieldNames().length == 0);
    
public booleanisValid()
Returns true if all of the fields have legal values given their names. This method always returns true, but a subclass can override it to return false when appropriate.

return
true if the values are legal.
exception
RuntimeOperationsException if the validity checking fails. The method returns false if the descriptor is not valid, but throws this exception if the attempt to determine validity fails.

        return true;
    
private static java.util.SortedMapmakeMap(java.lang.String[] fieldNames, java.lang.Object[] fieldValues)

        if (fieldNames == null || fieldValues == null)
            throw new IllegalArgumentException("Null array parameter");
        if (fieldNames.length != fieldValues.length)
            throw new IllegalArgumentException("Different size arrays");
        SortedMap<String, Object> map =
                new TreeMap<String, Object>(String.CASE_INSENSITIVE_ORDER);
        for (int i = 0; i < fieldNames.length; i++) {
            String name = fieldNames[i];
            if (name == null || name.equals(""))
                throw new IllegalArgumentException("Empty or null field name");
            Object old = map.put(name, fieldValues[i]);
            if (old != null) {
                throw new IllegalArgumentException("Duplicate field name: " +
                                                   name);
            }
        }
        return map;
    
private static java.util.SortedMapmakeMap(java.lang.String[] fields)

        if (fields == null)
            throw new IllegalArgumentException("Null fields parameter");
        String[] fieldNames = new String[fields.length];
        String[] fieldValues = new String[fields.length];
        for (int i = 0; i < fields.length; i++) {
            String field = fields[i];
            int eq = field.indexOf('=");
            if (eq < 0) {
                throw new IllegalArgumentException("Missing = character: " +
                                                   field);
            }
            fieldNames[i] = field.substring(0, eq);
            // makeMap will catch the case where the name is empty
            fieldValues[i] = field.substring(eq + 1);
        }
        return makeMap(fieldNames, fieldValues);
    
static javax.management.DescriptornonNullDescriptor(javax.management.Descriptor d)

        if (d == null)
            return EMPTY_DESCRIPTOR;
        else
            return d;
    
private java.lang.ObjectreadResolve()
This method can replace a deserialized instance of this class with another instance. For example, it might replace a deserialized empty ImmutableDescriptor with {@link #EMPTY_DESCRIPTOR}.

return
the replacement object, which may be {@code this}.
throws
InvalidObjectException if the read object has invalid fields.

        if (names.length == 0 && getClass() == ImmutableDescriptor.class)
            return EMPTY_DESCRIPTOR;

        boolean bad = false;
        if (names == null || values == null || names.length != values.length)
            bad = true;
        if (!bad) {
            final Comparator<String> compare = String.CASE_INSENSITIVE_ORDER;
            String lastName = ""; // also catches illegal null name
            for (int i = 0; i < names.length; i++) {
                if (names[i] == null ||
                        compare.compare(lastName, names[i]) >= 0) {
                    bad = true;
                    break;
                }
                lastName = names[i];
            }
        }
        if (bad)
            throw new InvalidObjectException("Bad names or values");

        return this;
    
public final voidremoveField(java.lang.String fieldName)
Removes a field from the descriptor.

param
fieldName String name of the field to be removed. If the field name is illegal or the field is not found, no exception is thrown.
exception
RuntimeOperationsException if a field of the given name exists and the descriptor is immutable. The wrapped exception will be an {@link UnsupportedOperationException}.

        if (fieldName != null && fieldIndex(fieldName) >= 0)
            unsupported();
    
public final voidsetField(java.lang.String fieldName, java.lang.Object fieldValue)
This operation is unsupported since this class is immutable. If this call would change a mutable descriptor with the same contents, then a {@link RuntimeOperationsException} wrapping an {@link UnsupportedOperationException} is thrown. Otherwise, the behavior is the same as it would be for a mutable descriptor: either an exception is thrown because of illegal parameters, or there is no effect.

        checkIllegalFieldName(fieldName);
        int i = fieldIndex(fieldName);
        if (i < 0)
            unsupported();
        Object value = values[i];
        if ((value == null) ?
                (fieldValue != null) :
                !value.equals(fieldValue))
            unsupported();
    
public final voidsetFields(java.lang.String[] fieldNames, java.lang.Object[] fieldValues)
This operation is unsupported since this class is immutable. If this call would change a mutable descriptor with the same contents, then a {@link RuntimeOperationsException} wrapping an {@link UnsupportedOperationException} is thrown. Otherwise, the behavior is the same as it would be for a mutable descriptor: either an exception is thrown because of illegal parameters, or there is no effect.

        if (fieldNames == null || fieldValues == null)
            illegal("Null argument");
        if (fieldNames.length != fieldValues.length)
            illegal("Different array sizes");
        for (int i = 0; i < fieldNames.length; i++)
            checkIllegalFieldName(fieldNames[i]);
        for (int i = 0; i < fieldNames.length; i++)
            setField(fieldNames[i], fieldValues[i]);
    
public java.lang.StringtoString()

        StringBuilder sb = new StringBuilder("{");
        for (int i = 0; i < names.length; i++) {
            if (i > 0)
                sb.append(", ");
            sb.append(names[i]).append("=");
            Object v = values[i];
            if (v != null && v.getClass().isArray()) {
                String s = Arrays.deepToString(new Object[] {v});
                s = s.substring(1, s.length() - 1); // remove [...]
                v = s;
            }
            sb.append(String.valueOf(v));
        }
        return sb.append("}").toString();
    
public static javax.management.ImmutableDescriptorunion(javax.management.Descriptor descriptors)

Return an {@code ImmutableDescriptor} whose contents are the union of the given descriptors. Every field name that appears in any of the descriptors will appear in the result with the value that it has when the method is called. Subsequent changes to any of the descriptors do not affect the ImmutableDescriptor returned here.

In the simplest case, there is only one descriptor and the returned {@code ImmutableDescriptor} is a copy of its fields at the time this method is called:

Descriptor d = something();
ImmutableDescriptor copy = ImmutableDescriptor.union(d);

param
descriptors the descriptors to be combined. Any of the descriptors can be null, in which case it is skipped.
return
an {@code ImmutableDescriptor} that is the union of the given descriptors. The returned object may be identical to one of the input descriptors if it is an ImmutableDescriptor that contains all of the required fields.
throws
IllegalArgumentException if two Descriptors contain the same field name with different associated values. Primitive array values are considered the same if they are of the same type with the same elements. Object array values are considered the same if {@link Arrays#deepEquals(Object[],Object[])} returns true.

        // Optimize the case where exactly one Descriptor is non-Empty
        // and it is immutable - we can just return it.
        int index = findNonEmpty(descriptors, 0);
        if (index < 0)
            return EMPTY_DESCRIPTOR;
        if (descriptors[index] instanceof ImmutableDescriptor
                && findNonEmpty(descriptors, index + 1) < 0)
            return (ImmutableDescriptor) descriptors[index];

        Map<String, Object> map =
            new TreeMap<String, Object>(String.CASE_INSENSITIVE_ORDER);
        ImmutableDescriptor biggestImmutable = EMPTY_DESCRIPTOR;
        for (Descriptor d : descriptors) {
            if (d != null) {
                String[] names;
                if (d instanceof ImmutableDescriptor) {
                    ImmutableDescriptor id = (ImmutableDescriptor) d;
                    names = id.names;
                    if (id.getClass() == ImmutableDescriptor.class
                            && names.length > biggestImmutable.names.length)
                        biggestImmutable = id;
                } else
                    names = d.getFieldNames();
                for (String n : names) {
                    Object v = d.getFieldValue(n);
                    Object old = map.put(n, v);
                    if (old != null) {
                        boolean equal;
                        if (old.getClass().isArray()) {
                            equal = Arrays.deepEquals(new Object[] {old},
                                                      new Object[] {v});
                        } else
                            equal = old.equals(v);
                        if (!equal) {
                            final String msg =
                                "Inconsistent values for descriptor field " +
                                n + ": " + old + " :: " + v;
                            throw new IllegalArgumentException(msg);
                        }
                    }
                }
            }
        }
        if (biggestImmutable.names.length == map.size())
            return biggestImmutable;
        return new ImmutableDescriptor(map);
    
private static voidunsupported()

        UnsupportedOperationException uoe =
            new UnsupportedOperationException("Descriptor is read-only");
        throw new RuntimeOperationsException(uoe);