import java.util.*;
public class CollectionsFramework {
// main method
public static void main(String[] args) {
//declaring an array in java
int arr[] = {10, 20, 30, 40, 50};
for(int i=0; i < arr.length; i++)
{
System.out.print(" " + arr[i]);
}
// declaring any 2d array in Java or it can be used to declare the 1d matrix using new keyword
int arr[][] = new int[2][];
// Making the above array Jagged
// First row has 3 columns
arr[0] = new int[3];
// Second row has 2 columns
arr[1] = new int[2];
// Example
int[][] arr = { { 1, 2 }, { 3, 4 } };
System.out.println(Integer.bitCount(4)); // Gives out the set bits count in 4
// Strings in Java
String s= "GeeksforGeeks";
// or String s= new String ("GeeksforGeeks");
// Returns the number of characters in the String.
System.out.println("String length = " + s.length());
// Returns the character at ith index.
System.out.println("Character at 3rd position = "
+ s.charAt(3));
// Return the substring from the ith index character
// to end of string
System.out.println("Substring " + s.substring(3));
// Returns the substring from i to j-1 index.
System.out.println("Substring = " + s.substring(2,5));
// Concatenates string2 to the end of string1.
String s1 = "Geeks";
String s2 = "forGeeks";
System.out.println("Concatenated string = " +
s1.concat(s2));
// Returns the index within the string
// of the first occurrence of the specified string.
String s4 = "Learn Share Learn";
System.out.println("Index of Share " +
s4.indexOf("Share"));
// Returns the index within the string of the
// first occurrence of the specified string,
// starting at the specified index.
System.out.println("Index of a = " +
s4.indexOf('a',3));
// Checking equality of Strings
Boolean out = "Geeks".equals("geeks");
System.out.println("Checking Equality " + out);
out = "Geeks".equals("Geeks");
System.out.println("Checking Equality " + out);
out = "Geeks".equalsIgnoreCase("gEeks ");
System.out.println("Checking Equality " + out);
//If ASCII difference is zero then the two strings are similar
int out1 = s1.compareTo(s2);
System.out.println("the difference between ASCII value is="+out1);
// Converting cases
String word1 = "GeeKyMe";
System.out.println("Changing to lower Case " +
word1.toLowerCase());
// Converting cases
String word2 = "GeekyME";
System.out.println("Changing to UPPER Case " +
word2.toUpperCase());
// Trimming the word
String word4 = " Learn Share Learn ";
System.out.println("Trim the word " + word4.trim());
// Replacing characters
String str1 = "feeksforfeeks";
System.out.println("Original String " + str1);
String str2 = "feeksforfeeks".replace('f' ,'g') ;
System.out.println("Replaced f with g -> " + str2);
// https://www.geeksforgeeks.org/how-to-learn-java-collections-a-complete-guide/
// Instantiate an ArrayList Object
// Integer is a wrapper class for
// the basic datatype int
ArrayList intArr = new ArrayList();
// Add elements using add() method
intArr.add(10);
intArr.add(12);
intArr.add(25);
intArr.add(19);
intArr.add(11);
intArr.add(3);
// Print the ArrayList on the console
System.out.println(intArr);
// Remove elements at index 1 and 4
intArr.remove(1);
intArr.remove(4);
// Print the ArrayList on the console
System.out.println(intArr);
// Check if intArr contains the element 25
if(intArr.contains(25))
{
System.out.println("The ArrayList contains 25");
}
else
{
System.out.println("No such element exists");
}
// Use get method to get the element at index 1
int elementAt1 = intArr.get(1);
System.out.println("The Element at index 1 now is " + elementAt1);
Collections.reverse(intArr); // reversing an arraylist
List arr = intArr.subList(st,en); // slicing of arraylist in java List is an interface of arraylist
//-------------------------------------------------------------------------------
Vector intVector = new Vector();
// Print the initial size of the Vector
System.out.println("The initial size of the Vector = " + intVector.size());
System.out.println();
// Add elements using add method
intVector.add(11);
intVector.add(18);
intVector.add(1);
intVector.add(87);
intVector.add(19);
intVector.add(11);
// Print the Vector on the console
System.out.println("The Vector intVector : ");
System.out.println(intVector);
System.out.println("Size of intVector : " + intVector.size());
System.out.println();
// Remove the element at index 2
intVector.remove(2);
// Print the vector again on the console
System.out.println("The Vector intVector after removing element at 2 : ");
System.out.println(intVector);
System.out.println();
// Clear all elements of the Vector and
// Print the Vector on the console
intVector.clear();
System.out.println("The Vector intVector after using clear : ");
System.out.println(intVector);
//--------------------------------------------------------------------------------------
Stack strStack = new Stack();
// Add elements using the push() method
strStack.push("Stack");
strStack.push("a");
strStack.push("is");
strStack.push("This");
// The size() method gives the
// number of elements in the Stack
System.out.println("The size of the Stack is : " + strStack.size());
// The search() method is
// used to search an element
// it returns the position of
// the element
int position = strStack.search("a");
System.out.println("\nThe string 'a' is at position " + position);
System.out.println("\nThe elements of the stack are : ");
String temp;
int num = strStack.size();
for(int i = 1; i