import java.util.ArrayList
List<Integer> arrList = new ArrayList<Integer>(10);
arrList.add(1);
arrList.add(2);
arrList.add(3);
arrList.add(4);
arrList.add(5);
arrList.add(6);
System.out.println(arrList); 1,2,3,4,5,6
arrList.remove(3); remove 3rd element that is 4
LinkedList
LinkedList<String> linkist = new LinkedList<String>();
linkist .add("A");
linkist .addLast("C");
linkist .addFirst("D");
linkist .add(2,"B");
// D A B C
linkist .remove("C");
linkist .add(2); //by position
linkist .removeFirst("A");
linkist .removeLast("A");
Hashset
Set<String> hashset = new HashSet<>();
boolean ret = bhashset.add("A"); //true if added false if not added
hashset.add("B");
hashset.add("B"); ///return false here
hashset.contains("A");
hashset.remove("A");
HashMap
Map<String, Integer> hmap = new HashMap<>();
hmap.put("a",10);
hmap.put("b",20);
hmap.put("c",30);
// { a=10, b=20, c=30}
hmap.size(); // 3
hmap.containsKey("a"); //boolean
hmap.get("a");
hmap.keySet(); // array of keys
for(String k: hmap.keySet()){
// hmap.get(k);
}
for(Entry <String, Integer> data : hmap.entrySet()){
// data.getKey();
// data.getValue();
}
TreeSet
Naturally sorted in Treeset
TreeSet<String> tset = new TreeSet<String>();
tset.add("B");
tset.add("A");
tset.add("C");
tset.add("C");
// A, B, C // sort //ordered by default
TreeMap
Naturally sorted in Treeap
Map< Integer, String> tmap= new HashMap<>();
tmap.put(1,"a");
mtap.put(2,"b");
tmap.put(3,"c");
// {1=a,2=b,3=c}
Map< String, Integer> tmap= new HashMap<>();
tmap.put("b",2);
mtap.put("a",1);
tmap.put("c",3);
// {a=1,b=2,c=3}
Stacks
Stack <String> stack = new Stack<>();
stack.push("A");
stack.push("B");
stack.push("C");
String poped = stack.pop(); // C remove from stack
String peeked = stack.peek(); // C , doesnt remove from stack
//Stack is filo
Queue
// fifo arrangement
Queue<> que = new PriorityQueue<>();
que .push("A");
que .push("B");
que .push("C");
que.remove(); //
que.peek(); //
que.poll(); //