check if key exists in dictionary java code example

Example 1: check if map contains key java

if (map.containsKey(key)) {
       // Okay, there's a key but the value is null
    } else {
       // Definitely no such key
    }

Example 2: java check if key exists in list

if (lista.contains(conta1)) {
    System.out.println("Account found");
} else {
    System.out.println("Account not found");
}