El método contains(E e) de CopyOnWriteArrayList comprueba si un elemento dado está presente en la lista o no. Si el elemento aparece al menos una vez, la función devuelve verdadero, de lo contrario, devuelve falso.
Sintaxis:
public boolean contains(Object o)
Parámetros: La función acepta un único parámetro obligatorio o que especifica el elemento cuya apariencia se va a comprobar en la lista.
Valor devuelto: la función devuelve verdadero si el elemento está presente al menos una vez en la lista; de lo contrario, devuelve falso.
Los siguientes programas ilustran la función anterior:
Programa 1:
// Java Program to illustrate the CopyOnWriteArrayList
// contains() method in Java
import java.util.concurrent.CopyOnWriteArrayList;
import java.util.*;
public class GFG {
public static void main(String[] args)
{
// create object of CopyOnWriteArrayList
CopyOnWriteArrayList<Integer> ArrLis
= new CopyOnWriteArrayList<Integer>();
// Add elements
ArrLis.add(32);
ArrLis.add(67);
ArrLis.add(98);
ArrLis.add(100);
// print CopyOnWriteArrayList
System.out.println("CopyOnWriteArrayList: " + ArrLis);
// check using function
if (ArrLis.contains(100))
System.out.println("100 is present in the list");
else
System.out.println("100 is not present in the list");
// check using function
if (ArrLis.contains(20))
System.out.println("20 is present in the list");
else
System.out.println("20 is not present in the list");
}
}
Producción:
CopyOnWriteArrayList: [32, 67, 98, 100] 100 is present in the list 20 is not present in the list
Programa 2:
// Java Program to illustrate the CopyOnWriteArrayList
// contains() method in Java
import java.util.concurrent.CopyOnWriteArrayList;
import java.util.*;
public class GFG {
public static void main(String[] args)
{
// create object of CopyOnWriteArrayList
CopyOnWriteArrayList<String> ArrLis
= new CopyOnWriteArrayList<String>();
// Add elements
ArrLis.add("gopal");
ArrLis.add("gfg");
ArrLis.add("jgec");
ArrLis.add("sudo");
// print CopyOnWriteArrayList
System.out.println("CopyOnWriteArrayList: " + ArrLis);
// check using function
if (ArrLis.contains("gfg"))
System.out.println("'gfg' is present in the list");
else
System.out.println("'gfg' is not present in the list");
// check using function
if (ArrLis.contains("best"))
System.out.println("'best' is present in the list");
else
System.out.println("'best' is not present in the list");
}
}
Producción:
CopyOnWriteArrayList: [gopal, gfg, jgec, sudo] 'gfg' is present in the list 'best' is not present in the list
Referencia: https://docs.oracle.com/javase/8/docs/api/java/util/concurrent/CopyOnWriteArrayList.html#contains-E-