- Java.util Package Classes
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- Java.util - Properties
- Java.util - PropertyPermission
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- Java.util - Random
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- Java.util - ServiceLoader
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- Java.util - Stack
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- Java.util - TimerTask
- Java.util - TimeZone
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- Java.util - TreeSet
- Java.util - UUID
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- Java.util Package Extras
- Java.util - Interfaces
- Java.util - Exceptions
- Java.util - Enumerations
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- Java.util - Discussion
Java Collections emptyList() Method
Description
The Java Collections emptyList() method is used to get the empty list. List is immutable and cannot be modified. This list is serializable.
Declaration
Following is the declaration for Java Collections emptyList() method.
public static final <T> List<T> emptyList()
Parameters
NA
Return Value
NA
Exception
NA
Getting Empty List of Integers Example
The following example shows the usage of Java Collection emptyList() method to get an empty list of Integers. We've created an empty list using emptyList() method and then tried adding few elements to it which results in exception.
package com.tutorialspoint; import java.util.Collections; import java.util.List; public class CollectionsDemo { public static void main(String args[]) { // create an empty list List<Integer> emptylst = Collections.emptyList(); System.out.println("Created empty immutable list: "+emptylst); // try to add elements emptylst.add(1); emptylst.add(2); } }
Output
Let us compile and run the above program, this will produce the following result.Exception will be thrown as the list is immutable.
Created empty immutable list: [] Exception in thread "main" java.lang.UnsupportedOperationException at java.base/java.util.AbstractList.add(AbstractList.java:153) at java.base/java.util.AbstractList.add(AbstractList.java:111) at com.tutorialspoint.CollectionsDemo.main(CollectionsDemo.java:15)
Getting Empty List of Strings Example
The following example shows the usage of Java Collection emptyList() method to get an empty list of Strings. We've created an empty list using emptyList() method and then tried adding few elements to it which results in exception.
package com.tutorialspoint; import java.util.Collections; import java.util.List; public class CollectionsDemo { public static void main(String args[]) { // create an empty list List<String> emptylst = Collections.emptyList(); System.out.println("Created empty immutable list: "+emptylst); // try to add elements emptylst.add("A"); emptylst.add("B"); } }
Output
Let us compile and run the above program, this will produce the following result.Exception will be thrown as the list is immutable.
Created empty immutable list: [] Exception in thread "main" java.lang.UnsupportedOperationException at java.base/java.util.AbstractList.add(AbstractList.java:153) at java.base/java.util.AbstractList.add(AbstractList.java:111) at com.tutorialspoint.CollectionsDemo.main(CollectionsDemo.java:15)
Getting Empty List of Objects Example
The following example shows the usage of Java Collection emptyList() method to get an empty list of Student objects. We've created an empty list using emptyList() method and then tried adding few elements to it which results in exception.
package com.tutorialspoint; import java.util.Collections; import java.util.List; public class CollectionsDemo { public static void main(String args[]) { // create an empty list List<Student> emptylst = Collections.emptyList(); System.out.println("Created empty immutable list: "+emptylst); // try to add elements emptylst.add(new Student(1, "Julie")); emptylst.add(new Student(2, "Robert")); } } class 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 + " ]"; } }
Output
Let us compile and run the above program, this will produce the following result.Exception will be thrown as the list is immutable.
Created empty immutable list: [] Exception in thread "main" java.lang.UnsupportedOperationException at java.base/java.util.AbstractList.add(AbstractList.java:153) at java.base/java.util.AbstractList.add(AbstractList.java:111) at com.tutorialspoint.CollectionsDemo.main(CollectionsDemo.java:15)
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