The Object and Objects Classes - Beginning Java 8 Fundamentals - page 309

public class ObjectsTest {
public static void main(String[] args) {
// Compute hash code for two integers, a char, and a string
int hash = Objects.hash(10, 8900, '\u20b9', "Hello");
System.out.println("Hash Code is " + hash);
// Test for equality
boolean isEqual = Objects.equals(null, null);
System.out.println("null is equal to null: " + isEqual);
isEqual = Objects.equals(null, "XYZ");
System.out.println("null is equal to XYZ: " + isEqual);
// toString() method test
System.out.println("toString(null) is " + Objects.toString(null));
System.out.println("toString(null, \"XXX\") is " + Objects.toString(null, "XXX"));
// Testing requireNonNull(T obj, String message)
try {
printName("Doug Dyer");
printName(null);
}
catch (NullPointerException e) {
System.out.println(e.getMessage());
}
// requireNonNull(T obj, Supplier<String> messageSupplier)
try {
// Using a lambda expression to create a Supplier<String> object.
// The Supplier returns a timestamped message.
Supplier<String> messageSupplier = () -> "Name is required. Error generated
on " + Instant.now();
printNameWithSuplier("Babalu", messageSupplier);
printNameWithSuplier(null, messageSupplier);
}
catch (NullPointerException e) {
System.out.println(e.getMessage());
}
}
public static void printName(String name) {
// Test name for not null. Generate a NullPointerException if it is null.
Objects.requireNonNull(name, "Name is required.");
// Print the name if the above statement dod not throw an exception
System.out.println("Name is " + name);
}