Pineapple-Cheese Casserole

1 (20 ounce) can pineapple chunks
1 cup sharp Cheddar cheese, grated
1/2 cup granulated sugar
3 tablespoons flour
1/4 cup butter
1 cup crumbled Ritz crackers
3 tablespoons pineapple juice

Combine all ingredients except butter and crumbs. Melt butter and mix with cracker crumbs. Spread over top. Bake at 350 degrees F for 20 to 30 minutes.