aList.add("Hello, ");
aList.add("This is");
aList.add("ArrayList");
aList.add(1, "Guys");//Adding data at specified index
//Displaying arrayList contents
System.out.print(aList); //It will display all contents without loop //Displaying arrayList contents/data on console through for loop
for (int index = 0; index < aList.size(); index++) {
System.out.print(aList.get(index) + " ");
}
//Displaying arrayList contents through foreach loop
for (Object object : aList) {
System.out.print(object + " ");
}
//Displaying arrayList contents using "Iterator" class object
Iterator it = aList.iterator(); while(it.hasNext()) {
System.out.print(it.next() + " ");
}
//Displaying size of arrayList
System.out.println(aList.size());
//Getting content/data at a specified index in arratList
String str = (String)aList.get(2);//getting data of index 2
System.out.println(str); //it displays ArrayList
//Removing content of arrayList at specified index
aList.remove(2);
//Removing content of arrayList by specifying object
aList.remove("This is");
//For specifying the arrayList to hold Integer data in it
ArrayList<Integer> integerList = new ArrayList<Integer>();
integerList.add(1);
integerList.add(2);
integerList.add(3);
integerList.add(4);
//Displaying integerList contents on console through for loop
for (int i = 0; i < integerList.size(); i++) {
System.out.print(integerList.get(i) + " ");
}
//For specifying the arrayList to hold String data in it
ArrayList<String> stringList = new ArrayList<String>(); //Adding arrayList contents and showing their sum
ArrayList intArrayList = new ArrayList();
intArrayList.add("5");
intArrayList.add("4");
intArrayList.add("2");
intArrayList.add("3");
intArrayList.add("1");
//way one to sum up contents
int sum = 0;
for (int i = 0; i < intArrayList.size(); i++) {
String str = (String)intArrayList.get(i);
sum += Integer.parseInt(str); //casting string to integer
}
System.out.print("The sum of arrayList contents is : " + sum);
//way second to sum up contents through Object array
int sum2 = 0;
Object[] objArray = intArrayList.toArray();//arrayList elements to object array
for (int i = 0; i < objArray.length; i++) {
sum2 += Integer.parseInt(objArray[i].toString());
}
System.out.print("The sum of arrayList contents is : " + sum2);
//Sorting a arrayList
Collections.sort(intArrayList);
HashMap:
HashMap hm = new HashMap();
hm.put("1", "Rehan");
hm.put("2", "Maryam");
hm.put("3", "Zainab");
hm.put("4", "Ayaan");
hm.put("5", "Cruise");
//Dispalying HashMap contents
System.out.println(hm);
//Or
System.out.print(hm.values());
//Displaying Through Loop/Iterator
Set set = hm.entrySet();
Iterator it = set.iterator();
while(it.hasNext()) {
Map.Entry me = (Map.Entry)it.next();
System.out.println(me.getKey() + " = " + me.getValue());
}
//Sorting values in HashMap Way One
SortedSet sortedSetKey = new TreeSet(hm.keySet());
Iterator iKey = sortedSetKey.iterator();
while (iKey.hasNext()) {
String key = iKey.next().toString();
String value = hm.get(key).toString();
System.out.println(key + " = " + value);
}
//Sorting a HashMap Way Two
Vector v = new Vector(hm.keySet());
Collections.sort(v);
for(Enumeration e = v.elements(); e.hasMoreElements();) {
String key = e.nextElement().toString();
String value = hm.get(key).toString();
System.out.println(key + " = " + value);
}
//Removing Content From HashMap By Specifying Key
hm.remove("5");
System.out.print(hm);//it removes the value of "5 = Cruise" in HashMap
//Specifying the HashMap to hold key as Integer and value as String in it
HashMap<Integer, String> hash = new HashMap<Integer, String>();
hash.put(1, "Its Me");
hash.put(2, "Its You");
hash.put(5, "Who are you?");
hash.put(3, "Are you ok?");
System.out.print(hash);
Stack:
Stack st = new Stack();
st.push("This");
st.push("is");
st.push("stack");
//Displaying Stack Contents
for(int i = 0 ; i < st.size(); i++) {
System.out.print(st.get(i) + " "); //it displays "This is stack"
}
//Displaying Stack Contents
while(!st.empty()) {
System.out.print(st.pop() + " "); //it displays "stack is This"
}
LinkedList:
LinkedList ll = new LinkedList();
ll.add("Proud");
ll.add("To");
ll.add("Be");
ll.add("A Pakistani");
//Displaying All LinkedList Nodes
System.out.println(ll);
//Adding Collection in LinkedList
ArrayList al = new ArrayList();
al.add("Pakistan");
al.add("is");
al.add("a islamic");
al.add("republic");
al.add("state");
LinkedList ll2 = new LinkedList(al); //adding ArrayList in LinkedList
//Displaying All LinkedList Nodes
System.out.println(ll2);
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