My tree has about 4 :'( Normally it has hundreds and my pear trees have no fruit at all.
Oh well we did get a late frost so I guess that was the problem
When we had the apple trees in flower, it wasn't so much the frost but the neverending rain. No pollinators were flying and doing the job. This could have happened to your walnut too.
We have one pear tree, variety Dr Jules Guyot, which has a habit of spreading its flowering time. In fact, I spotted a few flowers last week. This pear tree does have a good number of fruitlets on, even if the rest of the trees looks very bare.
I wonder whether this is a trait of the variety and will work for everybody, or whether this is just our tree for whatever reason. By the way, these late flowers do produce fruit, not yellow but greenish with stripes, ripening during October. They taste fine and have NO pips inside. Very peculiar. I showed a fruit to the experts at a fruit identification event and they said that they had seen this before, so this must happen with other pear varieties too.
In a year like this, such flowering habits will ensure a fruit set.