Programming Articles - Page 2904 of 3366

A stack can be implemented using a LinkedList by managing the LinkedList as a stack. This is done by using a class Stack which contains some of the Stack methods such as push(), top(), pop() etc.A program that demonstrates this is given as follows −Example Live Demoimport java.util.LinkedList; class Stack { private LinkedList l = new LinkedList(); public void push(Object obj) { l.addFirst(obj); } public Object top() { return l.getFirst(); } public ... Read More

The subList of a LinkedList can be obtained using the java.util.LinkedList.subList(). This method takes two parameters i.e. the start index for the sub-list(inclusive) and the end index for the sub-list(exclusive) from the required LinkedList. If the start index and the end index are the same, then an empty sub-list is returned.A program that demonstrates this is given as follows −Example Live Demoimport java.util.LinkedList; import java.util.List; public class Demo { public static void main(String[] args) { LinkedList l = new LinkedList(); l.add("John"); ... Read More

An element can be removed from a stack using the java.util.Stack.pop() method. This method requires no parameters and it removes the element at the top of the stack. It returns the element that was removed.A program that demonstrates this is given as follows −Example Live Demoimport java.util.Stack; public class Demo { public static void main (String args[]) { Stack stack = new Stack(); stack.push("Apple"); stack.push("Mango"); stack.push("Guava"); stack.push("Pear"); ... Read More

A stack in Java is a data structure that is used for storing elements. It follows the LIFO (Last In, First Out) principle. If we add an element to the stack last, it will be added at the top of the stack (thus it will be the first one to be picked). If we add another element to the stack, the previously added element will be pushed down, and the new element will be added at the top. We can not access previously added elements until we remove the top element.Add an Element to a Stack in Java In ... Read More

To get the element ordered first i.e. the first element in TreeSet, use the first() method.Create a TreeSet and add elements to it −TreeSet set = new TreeSet(); set.add("65"); set.add("45"); set.add("19"); set.add("27"); set.add("89"); set.add("57");Now, get the first element −set.first()The following is an example to get the element ordered first in TreeSet −Example Live Demoimport java.util.*; public class Demo { public static void main(String args[]) { TreeSet set = new TreeSet(); set.add("65"); set.add("45"); set.add("19"); ... Read More

First, create a TreeSet and add elements to it −TreeSet set = new TreeSet(); set.add("65"); set.add("45"); set.add("19"); set.add("27"); set.add("89"); set.add("57");Now, sort it in ascending order, which is the default −Iterator i = set.iterator(); while(i.hasNext()){ System.out.println(i.next()); }If you want to sort in descending order, then use the descendingIterator() method −Iterator j = set.descendingIterator(); while(j.hasNext()) { System.out.println(j.next()); }The following is an example to sort items in a TreeSet in ascending and descending order −Example Live Demoimport java.util.*; public class Demo { public static void main(String args[]){ TreeSet set ... Read More

A particular element can be searched in a LinkedList using the method java.util.LinkedList.indexOf(). This method returns the index of the first occurance of the element that is searched. If the element is not available in the LinkedList, then this method returns -1.A program that demonstrates this is given as follows −Example Live Demoimport java.util.LinkedList; public class Demo { public static void main(String[] args) { LinkedList l = new LinkedList(); l.add("A"); l.add("B"); l.add("C"); ... Read More

Use the clear() method to remove all elements from TreeSet.First, create a TreeSet and add elements −TreeSet set = new TreeSet(); set.add("65"); set.add("45"); set.add("19"); set.add("27"); set.add("89"); set.add("57");Now, remove all the elements −set.clear();The following is an example to remove all elements from TreeSet −Example Live Demoimport java.util.*; public class Demo { public static void main(String args[]){ TreeSet set = new TreeSet(); set.add("65"); set.add("45"); set.add("19"); set.add("27"); ... Read More

Use the remove() method to remove specified elements from TreeSet.At first, create a TreeSet and add elements −TreeSet set = new TreeSet(); set.add("34"); set.add("12"); set.add("67"); set.add("54"); set.add("76"); set.add("49");Now, remove the specified element i.e. 34 here −set.remove("34")The following is an example to remove specified element from TreeSet −Example Live Demoimport java.util.*; public class Demo { public static void main(String args[]){ TreeSet set = new TreeSet(); set.add("34"); set.add("12"); set.add("67"); set.add("54"); ... Read More

Use the clear() method to remove all values from TreeMap.Let us first create a TreeMap −TreeMap m = new TreeMap();Add some elements to the TreeMap −m.put(1, "PHP"); m.put(2, "jQuery"); m.put(3, "JavaScript"); m.put(4, "Ruby"); m.put(5, "Java"); m.put(6, "AngularJS"); m.put(7, "ExpressJS");Let us now remove all the values −m.clear();The following is an example to remove all values from TreeMap −Example Live Demoimport java.util.*; public class Demo { public static void main(String args[]) { TreeMap m = new TreeMap(); m.put(1, "PHP"); m.put(2, "jQuery"); ... Read More