package maps;
import java.util.*;
import java.util.stream.Collectors;
import java.util.stream.IntStream;
public class MapWithNPE {
public static void main(String[] args) {
try {
// Step 1: Define Two Lists (Handling Nulls)
List integerList = Arrays.asList(101, 102, 103);
List stringList = Arrays.asList("Apple", "Banana", null); // Contains null
// Step 2: Validate Lists Before Processing
if (integerList == null || stringList == null) {
throw new NullPointerException("One of the lists is null!");
}
if (integerList.contains(null) || stringList.contains(null)) {
throw new NullPointerException("List contains null values!");
}
// Step 3: Convert Lists to Map with Merge Function
@SuppressWarnings("unused")
Map stringIntegerMap = IntStream.range(0, Math.min(integerList.size(), stringList.size()))
.boxed()
.collect(Collectors.toMap(
stringList::get,
integerList::get,
(existingValue, newValue) -> existingValue // ✅ Keeps first value, ignores duplicates
));
System.out.println("Final Map: " + stringIntegerMap);
} catch (NullPointerException e) {
System.err.println("Error: Null values found in the list! " + e.getMessage());
} catch (IllegalStateException e) {
System.err.println("Error: Duplicate keys found in the list! " + e.getMessage());
} catch (IndexOutOfBoundsException e) {
System.err.println("Error: Lists are not of equal length! " + e.getMessage());
} catch (RuntimeException e) {
System.err.println("Error: Unexpected Runtime Exception! " + e.getMessage());
}
}
}