Supplier

Supplier

Do not accept any arguments but return a value.

Difference between Supplier and Callable

1. Supplier does not throw (cannot handle exceptions) while Callable can.

   Supplier

   package java.util.function;
   
   /**
   ​ * Represents a supplier of results.
    *
   ​ * <p>There is no requirement that a new or distinct result be returned each
   ​ * time the supplier is invoked.
    *
   ​ * <p>This is a <a href="package-summary.html">functional interface</a>
   ​ * whose functional method is {@link #get()}.
    *
   ​ * @param <T> the type of results supplied by this supplier
    *
   ​ * @since 1.8
    */
   @FunctionalInterface
   public interface Supplier<T> {
   
       /**
   ​     * Gets a result.
        *
   ​     * @return a result
        */
       T get();
   }
   

   Callable

   package java.util.concurrent;
   
   /**
   ​ * A task that returns a result and may throw an exception.
   ​ * Implementors define a single method with no arguments called
   ​ * {@code call}.
    *
   ​ * <p>The {@code Callable} interface is similar to {@link
   ​ * java.lang.Runnable}, in that both are designed for classes whose
   ​ * instances are potentially executed by another thread.  A
   ​ * {@code Runnable}, however, does not return a result and cannot
   ​ * throw a checked exception.
    *
   ​ * <p>The {@link Executors} class contains utility methods to
   ​ * convert from other common forms to {@code Callable} classes.
    *
   ​ * @see Executor
   ​ * @since 1.5
   ​ * @author Doug Lea
   ​ * @param <V> the result type of method {@code call}
    */
   @FunctionalInterface
   public interface Callable<V> {
       /**
   ​     * Computes a result, or throws an exception if unable to do so.
        *
   ​     * @return computed result
   ​     * @throws Exception if unable to compute a result
        */
       V call() throws Exception;
   }
   

2. When the helper function throws exceptions, the compiler will not let us use Suppliers. We have to use Callables. If we use Suppliers, we have to use try/catch block and handle that exception explicitly.

Tags

Collections - Infinite Lists