Valid attribute names are case-insensitive, and they are restricted to the ASCII characters in the set of [0-9,a-z, A-Z_-], and cannot be exceeded over 70 characters in length. The attribute’s value can contain any characters and will be encoded in UTF-8 when written to the output stream in any program. This is the source code of the Java program to Implement Attributes API. The program is successfully run and the output of the program is also shown below:
Procedure:
- Setting attributes
- Creating an object of class in main() method and name it as ‘attribute’.
- Assigning attributes.
- Stores the value Value associated with key name in this Attribute using putValue() method.
- Returns a Set containing all the keys found in this Attributes using keySet() method.
- Iterator to traverse over collection interface of the object type.
- Checking condition using hasNext() method which holds true till there is a single element left in order to print the elements.
- Clearing all attribute objects from the collection using clear() method.
- Lastly, printing the display message whether the attribute is empty or not.
Implementation:
Example
Java
// Java Program to Implement Attribute API// Importing classes from// java.util packageimport java.util.Collection;import java.util.Iterator;import java.util.Map;import java.util.Map.Entry;import java.util.Set;import java.util.jar.Attributes;// Classpublic class GFG { private Attributes attributes; // Constructor 1 // Constructs a new, empty Attributes object // with default size public GFG() { attributes = new Attributes(); } // Constructor 2 // Constructs a new Attributes object // with the same attribute name-value mappings // as in the specified Attributes. public GFG(Attributes attr) { attributes = new Attributes(attr); } // Constructor 3 // Constructs a new, empty Attributes object // with the specified initial size. public GFG(int size) { attributes = new Attributes(size); } // Method 1 - clear() public void clear() { // Removes all attributes from this Map attributes.clear(); } // Method 2 - clone() public Object clone() { // Returns a copy of the Attributes // Returns true if this Map contains // the specified attribute name (key) return attributes.clone(); } // Method 3 - containsKey() public boolean containsKey(Object key) { // Returns true if this Map maps one or more // attribute names to the specified value. return attributes.containsKey(key); } // Method 4 - containsValue() public boolean containsValue(Object value) { // Returns a Collection view of the attribute // name-value mappings contained in this Map return attributes.containsValue(value); } // Method 5 - entrySet() public Set<Map.Entry<Object, Object> > entrySet() { // Returns the value of the specified attribute name // or NULL if the attribute name is not present return attributes.entrySet(); } // Method 6 - get() public Object get(Object key) { // Returns the value of the specified // Attributes.Name, or null if the attribute is not // present return attributes.get(key); } // Method 7 - getValue() public String getValue(Attributes.Name name) { // Returns the value of the specified attribute // name, specified as a string, or null if the // attribute was not found. return attributes.getValue(name); } // Method 8 - getValue() public String getValue(String name) { // Returns true if this Map contains no attributes return attributes.getValue(name); } // Method 9 - isEmpty() public boolean isEmpty() { // Returns a Set view of the attribute names (keys) // contained in this Map return attributes.isEmpty(); } // Method 10 - keySet() public Set<Object> keySet() { // Associates the specified value with the // specified attribute name (key) in this Map return attributes.keySet(); } // Method 11 - put() public Object put(Object key, Object value) { // Copies all of the attribute name-value mappings // from the specified attributes to this Map return attributes.put(key, value); } // Method 12 - putAll() public void putAll(Map<?, ?> m) { // Associates the specified value with // the specified attribute name, specified as a // String attributes.putAll(m); } // Method 13 - putValue() public String putValue(String name, String value) { // Removes the attribute with the specified // name(key) from this Map return attributes.putValue(name, value); } // Method 14 - remove() public Object remove(Object key) { // Returns the number of attributes in this Map return attributes.remove(key); } // Method 15 - size() public int size() { return attributes.size(); } // Method 16 - values() public Collection<Object> values() { // Returns a Collection view of the attribute values // contained in this Map return attributes.values(); } // Method 17 - main() driver method public static void main(String[] args) { // Setting attributes Attributes.Name CLASS_PATH = new Attributes.Name("CLASS_PATH"); Attributes.Name CONTENT_TYPE = new Attributes.Name("CONTENT_TYPE"); Attributes.Name MANIFEST_VERSION = new Attributes.Name("MANIFEST_VERSION"); // Creating an object of class in main() method GFG attribute = new GFG(); // Assigning attributes // Custom values attribute.put(CLASS_PATH, "root/sub_dir/class_path"); attribute.put(CONTENT_TYPE, "UTF-8"); attribute.put(MANIFEST_VERSION, "2"); // Stores the value Value associated with key name // in this Attribute attribute.putValue("MAIN_CLASS", "TESTMAIN.java"); // Display message System.out.println( "the key set of the Attributes is "); // Returns a Set containing all the keys found in // this Attributes Set<Object> keySet = attribute.keySet(); // Iterator to traverse over collection interface Iterator<Object> itr = keySet.iterator(); // Condition check using hasNext() method which // holds true till there is an element remaining while (itr.hasNext()) { System.out.print(itr.next() + "\t"); } // New Line System.out.println(); // Display message System.out.println( "the values of the Attributes is "); // Collection<Object> collectionValues = attribute.values(); itr = collectionValues.iterator(); // Condition check using hasNext() method which // holds true till there is an element remaining while (itr.hasNext()) { // Print the elements System.out.print(itr.next() + "\t"); } // New line System.out.println(); // Display message System.out.println( "the entry set of the Attributes is "); Iterator<Entry<Object, Object> > eitr; Set<Entry<Object, Object> > entrySet = attribute.entrySet(); eitr = entrySet.iterator(); // Condition check using hasNext() method which // holds true till there is an element remaining while (eitr.hasNext()) { // Print all elements System.out.println(eitr.next() + "\t"); } // Print and display messages System.out.println( "the Attributes contains Key CLASS_PATH:" + attribute.containsKey(CLASS_PATH)); System.out.println( "the Attributes contains Value TESTMAIN.java :" + attribute.containsValue("TESTMAIN.java")); System.out.println("the size of the Attributes is " + attribute.size()); // Clearing all attribute objects from the // collection attribute.clear(); // Determines whether this attribute contains any // keys if (attribute.isEmpty()) // Print the display message System.out.println("the Attributes is empty"); else // Print the display message System.out.println( "the Attributes is not empty"); }} |
Output
the key set of the Attributes is CLASS_PATH CONTENT_TYPE MANIFEST_VERSION MAIN_CLASS the values of the Attributes is root/sub_dir/class_path UTF-8 2 TESTMAIN.java the entry set of the Attributes is CLASS_PATH=root/sub_dir/class_path CONTENT_TYPE=UTF-8 MANIFEST_VERSION=2 MAIN_CLASS=TESTMAIN.java the Attributes contains Key CLASS_PATH:true the Attributes contains Value TESTMAIN.java :true the size of the Attributes is 4 the Attributes is empty
