Example
Verify the existence of a key within a map.
import java.util.HashMap;
public class Main {
public static void main(String[] args) {
HashMap<String, String> capitalCities = new HashMap<String, String>();
capitalCities.put("England", "London");
capitalCities.put("Germany", "Berlin");
capitalCities "Oslo");
capitalCities.put("USA", "Washington DC");
System.out.println(capitalCities.containsKey("England"));
System.out.println(capitalCities.containsKey("Canada"));
}
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Definition and Usage
The containsKey() method returns true if a map contains an entry with the specified key, and false otherwise.
Syntax
public boolean containsKey(Object key)
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Parameter Values
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Parameter
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Description
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key
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Required: The key to be searched for.
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Technical Details
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Returns:
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It returns true if an entry with the specified key exists in the map; otherwise, it returns false.
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