Dictionary classes in java

Dictionary classes in java

The Dictionary class is the abstract parent of any class, such as Hashtable , which maps keys to values. Every key and every value is an object. In any one Dictionary object, every key is associated with at most one value. Given a Dictionary and a key, the associated element can be looked up. Any non- null object can be used as a key and as a value. As a rule, the equals method should be used by implementations of this class to decide if two keys are the same. NOTE: This class is obsolete. New implementations should implement the Map interface, rather than extending this class.

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Constructor Detail

Dictionary

Method Detail

size

isEmpty

public abstract boolean isEmpty()

Tests if this dictionary maps no keys to value. The general contract for the isEmpty method is that the result is true if and only if this dictionary contains no entries.

keys

Returns an enumeration of the keys in this dictionary. The general contract for the keys method is that an Enumeration object is returned that will generate all the keys for which this dictionary contains entries.

elements

Returns an enumeration of the values in this dictionary. The general contract for the elements method is that an Enumeration is returned that will generate all the elements contained in entries in this dictionary.

get

Returns the value to which the key is mapped in this dictionary. The general contract for the isEmpty method is that if this dictionary contains an entry for the specified key, the associated value is returned; otherwise, null is returned.

put

Maps the specified key to the specified value in this dictionary. Neither the key nor the value can be null . If this dictionary already contains an entry for the specified key, the value already in this dictionary for that key is returned, after modifying the entry to contain the new element. If this dictionary does not already have an entry for the specified key, an entry is created for the specified key and value, and null is returned. The value can be retrieved by calling the get method with a key that is equal to the original key .

remove

Removes the key (and its corresponding value ) from this dictionary. This method does nothing if the key is not in this dictionary.

Submit a bug or feature
For further API reference and developer documentation, see Java SE Documentation. That documentation contains more detailed, developer-targeted descriptions, with conceptual overviews, definitions of terms, workarounds, and working code examples.
Copyright © 1993, 2023, Oracle and/or its affiliates. All rights reserved. Use is subject to license terms. Also see the documentation redistribution policy.

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Dictionary classes in java

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Dictionary classes in java

The Dictionary class is the abstract parent of any class, such as Hashtable , which maps keys to values. Every key and every value is an object. In any one Dictionary object, every key is associated with at most one value. Given a Dictionary and a key, the associated element can be looked up. Any non- null object can be used as a key and as a value. As a rule, the equals method should be used by implementations of this class to decide if two keys are the same. NOTE: This class is obsolete. New implementations should implement the Map interface, rather than extending this class.

Constructor Summary

Method Summary

Methods declared in class java.lang.Object

Constructor Detail

Dictionary

Method Detail

size

isEmpty

public abstract boolean isEmpty()

Tests if this dictionary maps no keys to value. The general contract for the isEmpty method is that the result is true if and only if this dictionary contains no entries.

keys

Returns an enumeration of the keys in this dictionary. The general contract for the keys method is that an Enumeration object is returned that will generate all the keys for which this dictionary contains entries.

elements

Returns an enumeration of the values in this dictionary. The general contract for the elements method is that an Enumeration is returned that will generate all the elements contained in entries in this dictionary.

get

Returns the value to which the key is mapped in this dictionary. The general contract for the isEmpty method is that if this dictionary contains an entry for the specified key, the associated value is returned; otherwise, null is returned.

put

Maps the specified key to the specified value in this dictionary. Neither the key nor the value can be null . If this dictionary already contains an entry for the specified key , the value already in this dictionary for that key is returned, after modifying the entry to contain the new element. If this dictionary does not already have an entry for the specified key , an entry is created for the specified key and value , and null is returned. The value can be retrieved by calling the get method with a key that is equal to the original key .

remove

Removes the key (and its corresponding value ) from this dictionary. This method does nothing if the key is not in this dictionary.

Report a bug or suggest an enhancement
For further API reference and developer documentation see the Java SE Documentation, which contains more detailed, developer-targeted descriptions with conceptual overviews, definitions of terms, workarounds, and working code examples.
Java is a trademark or registered trademark of Oracle and/or its affiliates in the US and other countries.
Copyright © 1993, 2023, Oracle and/or its affiliates, 500 Oracle Parkway, Redwood Shores, CA 94065 USA.
All rights reserved. Use is subject to license terms and the documentation redistribution policy.

Источник

Class Dictionary

The Dictionary class is the abstract parent of any class, such as Hashtable , which maps keys to values. Every key and every value is an object. In any one Dictionary object, every key is associated with at most one value. Given a Dictionary and a key, the associated element can be looked up. Any non- null object can be used as a key and as a value.

As a rule, the equals method should be used by implementations of this class to decide if two keys are the same.

NOTE: This class is obsolete. New implementations should implement the Map interface, rather than extending this class.

Constructor Summary

Method Summary

Methods declared in class java.lang.Object

Constructor Details

Dictionary

Method Details

size

isEmpty

Tests if this dictionary maps no keys to value. The general contract for the isEmpty method is that the result is true if and only if this dictionary contains no entries.

keys

Returns an enumeration of the keys in this dictionary. The general contract for the keys method is that an Enumeration object is returned that will generate all the keys for which this dictionary contains entries.

elements

Returns an enumeration of the values in this dictionary. The general contract for the elements method is that an Enumeration is returned that will generate all the elements contained in entries in this dictionary.

get

Returns the value to which the key is mapped in this dictionary. The general contract for the isEmpty method is that if this dictionary contains an entry for the specified key, the associated value is returned; otherwise, null is returned.

put

Maps the specified key to the specified value in this dictionary. Neither the key nor the value can be null . If this dictionary already contains an entry for the specified key , the value already in this dictionary for that key is returned, after modifying the entry to contain the new element. If this dictionary does not already have an entry for the specified key , an entry is created for the specified key and value , and null is returned. The value can be retrieved by calling the get method with a key that is equal to the original key .

remove

Removes the key (and its corresponding value ) from this dictionary. This method does nothing if the key is not in this dictionary.

Report a bug or suggest an enhancement
For further API reference and developer documentation see the Java SE Documentation, which contains more detailed, developer-targeted descriptions with conceptual overviews, definitions of terms, workarounds, and working code examples. Other versions.
Java is a trademark or registered trademark of Oracle and/or its affiliates in the US and other countries.
Copyright © 1993, 2023, Oracle and/or its affiliates, 500 Oracle Parkway, Redwood Shores, CA 94065 USA.
All rights reserved. Use is subject to license terms and the documentation redistribution policy.

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