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JAVA
how to make an arraylist java
ArrayList<Integer> integerArray = new ArrayList<Integer>();
ArrayList<String> stringArray = new ArrayList<String>();
ArrayList<Double> doubleArray = new ArrayList<Double>();
//... keep replacing what is inside the <> with the appropriate
//data type
how to make an array of arraylists in java
ArrayList<Integer> [] myList = (ArrayList<Integer>[]) new ArrayList[4];
java create arraylist
//dont forget to import ArrayList--> import java.util.ArrayList;
ArrayList<String> yourListName = new ArrayList<String>();
yourListName.add("Ace");
yourListName.add("Two");
yourListName.add("Three");
yourListName.add("J");
yourListName.add("Q");
//display list
for (String s : yourListName) {
System.out.println(s);
}
own arraylist in java
//Step 1 : Define CustomList interfaces
public interface CustomList<E> extends Iterable<E> {
boolean isEmpty();
int size();
boolean add(E element);
boolean add(int index, E element);
void remove(E element);
E get(int index);
int indexOf(E element);
void set(int index, E element);
boolean contains(E element);
void clear();
E[] toArray();
}
//Step2 : Implementation
package com.spacex.data.structure.list;
import java.util.Arrays;
import java.util.Iterator;
public class CustomArrayList<E> implements CustomList<E> {
private E[] elements;
private int size;
public CustomArrayList() {
this(10);
}
public CustomArrayList(int initSize) {
if (initSize < 0) {
throw new IllegalArgumentException("illegal size:" + initSize);
}
this.elements = (E[]) new Object[initSize];
}
@Override
public boolean isEmpty() {
return size() == 0;
}
@Override
public int size() {
return this.size;
}
private void ensureCapacity(int needCapacity) {
if (needCapacity > elements.length) {
Object[] oldElements = this.elements;
int newSize = this.size * 2 + 1;
this.elements = (E[]) new Object[newSize];
this.elements = (E[]) Arrays.copyOf(oldElements, newSize);
}
}
@Override
public boolean add(E element) {
ensureCapacity(this.size + 1);
elements[this.size++] = element;
return true;
}
private void checkRange(int index) {
if (index < 0 || index >= (this.size + 1)) {
throw new IllegalArgumentException("illegal index:" + index);
}
}
@Override
public boolean add(int index, E element) {
checkRange(index);
ensureCapacity(this.size + 1);
System.arraycopy(this.elements, index, elements, index + 1, size - index);
elements[index] = element;
this.size++;
return true;
}
@Override
public void remove(E element) {
if (element == null) {
for (int i = 0; i < this.size; i++) {
if (this.elements[i] == null) {
fastRemove(i);
return;
}
}
} else {
for (int i = 0; i < this.size; i++) {
if (element.equals(this.elements[i])) {
fastRemove(i);
return;
}
}
}
}
private void fastRemove(int index) {
int movedNumber = this.size - index - 1;
if (movedNumber > 0) {
System.arraycopy(this.elements, index + 1, this.elements, index, movedNumber);
}
this.elements[--this.size] = null;
}
@Override
public E get(int index) {
E e = this.elements[index];
return e;
}
@Override
public int indexOf(E element) {
if (element == null) {
for (int i = 0; i < this.elements.length; i++) {
if (this.elements[i] == null) {
return i;
}
}
} else {
for (int i = 0; i < this.elements.length; i++) {
if (element.equals(this.elements[i])) {
return i;
}
}
}
return -1;
}
@Override
public void set(int index, E element) {
checkRange(index);
ensureCapacity(this.size + 1);
this.elements[index] = element;
}
@Override
public boolean contains(E element) {
if (element == null) {
for (E e : this.elements) {
if (e == null) {
return true;
}
}
} else {
for (E e : this.elements) {
if (element.equals(e)) {
return true;
}
}
}
return false;
}
@Override
public void clear() {
for (int i = 0; i < this.size; i++) {
this.elements[i] = null;
}
this.size = 0;
}
@Override
public E[] toArray() {
return this.elements;
}
@Override
public Iterator<E> iterator() {
return new CustomIterator<>();
}
@Override
public String toString() {
return "CustomArrayList{" +
"elements=" + Arrays.toString(elements) +
", size=" + size +
'}';
}
private class CustomIterator<E> implements Iterator<E> {
private int current = 0;
@Override
public boolean hasNext() {
return this.current < size();
}
@Override
public E next() {
E value = (E) elements[current++];
return value;
}
}
}
java how to create arraylist
import java.util.ArrayList;
//create ArrayList
ArrayList<String> arrayList = new ArrayList<String>();
Java Create ArrayList in Java
import java.util.ArrayList;
class Main {
public static void main(String[] args){
// create ArrayList
ArrayList<String> languages = new ArrayList<>();
// Add elements to ArrayList
languages.add("Java");
languages.add("Python");
languages.add("Swift");
System.out.println("ArrayList: " + languages);
}
}
how to make a new arraylist java
ArrayList<Type> name = new ArrayList<Type>();
how to create an array list in java
List<Integer> list = new ArrayList<>();
Syntax of how to create ArrayList in Java
ArrayList<Type> arrayList= new ArrayList<>();
creating an array list in java
ArrayList<String> al = new ArrayList<String>();
how to create Java ArrayList
// welcome to softhunt.net
import java.util.ArrayList;
class Main {
public static void main(String[] args){
// create ArrayList
ArrayList<String> Websites = new ArrayList<>();
// Add elements to ArrayList
Websites.add("Softhunt.net");
Websites.add("Pythonprogramming.com");
Websites.add("Tutorial.io");
System.out.println("ArrayList: " + Websites);
}
}
How to create an ArrayList
ArrayList<Integer> list=new ArrayList<Integer>();
java make arraylist
//Create the Arraylist variable: . Replace the T with the type of
//data to be stored in the list.
ArrayList<T> exampleList = new ArrayList<>();
//You can now perform operations on this ArrayList
Java Creating an ArrayList
// create Integer type arraylist
ArrayList<Integer> arrayList = new ArrayList<>();
// create String type arraylist
ArrayList<String> arrayList = new ArrayList<>();
how to declare array of arraylist in java
List<List<Individual>> group = new ArrayList<List<Individual>>(4);
how to create arraylist in java
import java.util.ArrayList;
public class ArrayLists {
public static void main(String[] args) {
ArrayList<String> cars = new ArrayList<String>();
cars.add("Volvo");
cars.add("BMW");
cars.add("Ford");
cars.add("Mazda");
System.out.println(cars); // [Volvo, BMW, Ford, Mazda]
System.out.println(cars.isEmpty()); // false
System.out.println(cars.size()); // 4
cars.remove(0); // removes the element at index 0 (i.e. "Volvo")
System.out.println();
System.out.println(cars); // [BMW, Ford, Mazda]
System.out.println(cars.isEmpty()); // false
System.out.println(cars.size()); // 3
cars.remove(1); // removes the element at index 1 (i.e. "Ford")
System.out.println();
System.out.println(cars); // [BMW, Mazda]
cars.add("Mercedes");
System.out.println();
System.out.println(cars); // [BMW, Mazda, Mercedes]
cars.clear();
System.out.println();
System.out.println(cars); // []
System.out.println(cars.isEmpty()); // true
System.out.println(cars.size()); // 0
}
}
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