- Java.util Package Classes
- Java.util - Home
- Java.util - ArrayDeque
- Java.util - ArrayList
- Java.util - Arrays
- Java.util - BitSet
- Java.util - Calendar
- Java.util - Collections
- Java.util - Currency
- Java.util - Date
- Java.util - Dictionary
- Java.util - EnumMap
- Java.util - EnumSet
- Java.util - Formatter
- Java.util - GregorianCalendar
- Java.util - HashMap
- Java.util - HashSet
- Java.util - Hashtable
- Java.util - IdentityHashMap
- Java.util - LinkedHashMap
- Java.util - LinkedHashSet
- Java.util - LinkedList
- Java.util - ListResourceBundle
- Java.util - Locale
- Java.util - Observable
- Java.util - PriorityQueue
- Java.util - Properties
- Java.util - PropertyPermission
- Java.util - PropertyResourceBundle
- Java.util - Random
- Java.util - ResourceBundle
- Java.util - ResourceBundle.Control
- Java.util - Scanner
- Java.util - ServiceLoader
- Java.util - SimpleTimeZone
- Java.util - Stack
- Java.util - StringTokenizer
- Java.util - Timer
- Java.util - TimerTask
- Java.util - TimeZone
- Java.util - TreeMap
- Java.util - TreeSet
- Java.util - UUID
- Java.util - Vector
- Java.util - WeakHashMap
- Java.util Package Extras
- Java.util - Interfaces
- Java.util - Exceptions
- Java.util - Enumerations
- Java.util Useful Resources
- Java.util - Useful Resources
- Java.util - Discussion
Java TreeSet addAll() Method
Description
The Java TreeSet addAll(Collection c) method is used to add all of the elements in the specified collection to this set.
Declaration
Following is the declaration for java.util.TreeSet.addAll() method.
public boolean addAll(Collection c)
Parameters
c − These are the elements to be added.
Return Value
The method call returns true if this set changed as a result of the call.
Exception
ClassCastException − This exception is thrown if the elements provided cannot be compared with the elements currently in the set.
NullPointerException − This exception is thrown if the specified collection is null.
Adding Multiple Entries to a TreeSet of Integer Example
The following example shows the usage of Java TreeSet addAll() method to add multiple entries to the treeset in one go. We've created a TreeSet object of Integer. Then few entries are added using add() method to the treeset objects. Then first treeset is populated using addAll() method and then treeset is printed to validate the contents.
package com.tutorialspoint; import java.util.TreeSet; public class TreeSetDemo { public static void main(String[] args) { // creating a TreeSet TreeSet <Integer>treeone = new TreeSet<>(); TreeSet <Integer>treetwo = new TreeSet<>(); // adding in the treeone treeone.add(12); treeone.add(13); treeone.add(14); // adding in the treetwo treetwo.add(15); treetwo.add(16); treetwo.add(17); // adding treetwo to treeone treeone.addAll(treetwo); // displaying the Tree set data System.out.print("Tree set : " + treeone); } }
Output
Let us compile and run the above program, this will produce the following result.
Tree set : [12, 13, 14, 15, 16, 17]
Adding Multiple Entries to a TreeSet of String Example
The following example shows the usage of Java TreeSet addAll() method to add multiple entries to the treeset in one go. We've created a TreeSet object of String. Then few entries are added using add() method to the treeset objects. Then first treeset is populated using addAll() method and then treeset is printed to validate the contents.
package com.tutorialspoint; import java.util.TreeSet; public class TreeSetDemo { public static void main(String[] args) { // creating a TreeSet TreeSet <String>treeone = new TreeSet<>(); TreeSet <String>treetwo = new TreeSet<>(); // adding in the treeone treeone.add("12"); treeone.add("13"); treeone.add("14"); // adding in the treetwo treetwo.add("15"); treetwo.add("16"); treetwo.add("17"); // adding treetwo to treeone treeone.addAll(treetwo); // displaying the Tree set data System.out.print("Tree set : " + treeset); } }
Output
Let us compile and run the above program, this will produce the following result.
Tree set : [12, 13, 14, 15, 16, 17]
Adding Multiple Entries to a TreeSet of Object Example
The following example shows the usage of Java TreeSet addAll() method to add multiple entries to the treeset in one go. We've created a TreeSet object of Student objects. Then few entries are added using add() method to the treeset objects. Then first treeset is populated using addAll() method and then treeset is printed to validate the contents.
package com.tutorialspoint; import java.util.TreeSet; public class TreeSetDemo { public static void main(String[] args) { // creating a TreeSet TreeSet <Student>treeone = new TreeSet<>(); TreeSet <Student>treetwo = new TreeSet<>(); // adding in the treeone treeone.add(new Student(1, "Robert")); treeone.add(new Student(2, "Julie")); treeone.add(new Student(3, "Adam")); // adding in the treetwo treetwo.add(new Student(4, "Julia")); treetwo.add(new Student(5, "Alfred")); treetwo.add(new Student(6, "John")); // adding treetwo to treeone treeone.addAll(treetwo); // displaying the Tree set data System.out.print("Tree set : " + treeone); } } class Student implements Comparable<Student> { int rollNo; String name; Student(int rollNo, String name){ this.rollNo = rollNo; this.name = name; } @Override public String toString() { return "[ " + this.rollNo + ", " + this.name + " ]"; } @Override public boolean equals(Object obj) { Student s = (Student)obj; return this.rollNo == s.rollNo && this.name.equalsIgnoreCase(s.name); } @Override public int compareTo(Student student) { return this.rollNo - student.rollNo; } }
Output
Let us compile and run the above program, this will produce the following result.
Tree set : [[ 1, Robert ], [ 2, Julie ], [ 3, Adam ], [ 4, Julia ], [ 5, Alfred ], [ 6, John ]]
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