Thread safe lazy computation of final values using lambda.

Lazy.java

import java.util.Objects;
import java.util.function.Supplier;

public class Lazy<T> {
    private volatile T value;
    private final Supplier<T> supplier;
    private volatile boolean valueComputed = false;
    
    private Lazy(Supplier<T> supplier) { this.supplier = Objects.requireNonNull(supplier); }
    
    public static <T> Lazy<T> computeOnce(Supplier<T> supplier) { return new Lazy<>(supplier); }
    
    public T get() {
        if (valueComputed) return value;
        else return maybeComputeValue();
    }
    
    private synchronized T maybeComputeValue() {
        if (!valueComputed) {
            value = supplier.get();
            valueComputed = true;
        }
        return value;
    }
}