The containsKey(value) method of Properties class is used to check if this Properties object contains any mapping of this Key for any key present in it. It takes this value to be compared as parameter and returns a boolean value as result.
Syntax:
public Object containsKey(Object value)
Parameters: This method accepts a parameter value which is the key to be searched in this Properties.
Returns: This method returns a boolean value stating the result whether this key is present in this Properties object or not.
Below programs illustrate the containsKey(value) method:
Program 1:
// Java program to demonstrate// containsKey(value) method.  import java.util.*;  public class GFG {      // Main method    public static void main(String[] args)    {          // Create a properties and add some values        Properties properties = new Properties();        properties.put("Pen", 10);        properties.put("Book", 500);        properties.put("Clothes", 400);        properties.put("Mobile", 5000);          // Print Properties details        System.out.println("Current Properties: "                           + properties.toString());          // Check if Pen is present or not        // using containsKey()        System.out.println("Is Pen present: "                           + properties.containsKey("Pen"));    }} |
Output:
Current Properties: {Book=500, Mobile=5000, Pen=10, Clothes=400}
Is Pen present: true
Program 2:
// Java program to demonstrate// containsKey(value) method.  import java.util.*;  public class GFG {      // Main method    public static void main(String[] args)    {          // Create a properties and add some values        Properties properties = new Properties();          properties.put(1, "100RS");        properties.put(2, "500RS");        properties.put(3, "1000RS");          // print Properties details        System.out.println("Current Properties: "                           + properties.toString());          // Check if 5 is present or not        // using containsKey()        System.out.println("Is 5 present: "                           + properties.containsKey(5));    }} |
Output:
Current Properties: {3=1000RS, 2=500RS, 1=100RS}
Is 5 present: false
References: https://docs.oracle.com/javase/9/docs/api/java/util/Properties.html#containsKey-java.lang.Object-
