LOS ANGELES (AP) _ Character actor Adolph Caesar, who died of an apparent heart attack on the set where he was working in his latest film, had believed his career was only beginning after last year's Oscar nomination for ''A Soldier's Story,'' director Steven Spielberg said.

Caesar, 52, who co-starred in Spielberg's ''The Color Purple,'' suffered an apparent heart attack Thursday on the second day of shooting ''Tough Guys,'' a Walt Disney film starring Burt Lancaster and Kirk Douglas, according to Caesar's New York agent, Marvin Starkman.

''After 'A Soldier's Story,' his career took on a new life and Adolph often told me that this was just the beginning,'' said Spielberg. ''He was a gentle soul with a crusty surface and I am very saddened by this loss.''

Caesar's widow, Diane, said, ''He was just beginning. This is what he dreamed of all his life; somebody else was recognizing his talent.''

He recently completed another film, scheduled for release this spring, titled ''Paradise Island,'' starring Peter O'Toole, Robin Williams and Twiggy, Mrs. Caesar said in a telephone interview from New York.

He had no previous history of heart problems and had just undergone a physical examination for ''Tough Guys,'' she said.

After an autopsy, the actor's body will be flown home to Harlem for a Monday evening wake.

A private funeral will be held Tuesday, and a full memorial service will be held March 17 at a site to be announced, said Debbie McGee, a spokeswoman for the Negro Ensemble Company.

''We are trying to find a large theater to hold the memorial service,'' Ms. McGee said. ''Hattie Winston will be singing at the funeral service. Douglas Turner Ward, one of the co-founders of the Negro Ensemble Company, will speak.''

She said Caesar had appeared in many of the company's productions over the years, starting in 1970, including ''A Soldier's Play,'' which eventually became the Oscar-winning film, ''A Soldier's Story,'' about bigotry on a Southern military post during World War II.

Disney spokesman Gary Kalkin said Friday that Caesar actually had not yet appeared on camera in his supporting role in ''Tough Guys,'' so no scenes will need to be reshot.

''They obviously have to rearrange some of their scheduling, and that character is going to have to be recast,'' he said.

''We both admired Adolph as an actor, and in the short time we worked together, we both liked him as a man - filled with humor as well as talent,'' Douglas and Lancaster said in a joint statement.

In ''The Color Purple,'' nominated for 11 Academy Awards, Caesar played the father-in-law of Celie, the main character in the tale of family life in the South in the first half of the century.

His role as Sgt. Waters in 1984's ''A Soldier's Story'' had special meaning for Caesar. The story, told in flashbacks, revolves around the murder of Waters, whose pride and ambition make him violently intolerant of the flaws of his black troops.

''A painful experience of my own led me to Waters,'' Caesar said last year. ''I'd studied Shakespeare to death. I knew more about Shakespeare than Shakespeare knew about himself.

''After I did one season at a Shakespearean repertory company, a director said to me, 'You have a marvelous voice. You know the king's English well. You speak iambic pentameter. My suggestion is that you go to New York and get a good colored role.'''

Caesar won both the Obie and the New York Drama Desk Award for the Waters role in ''A Soldier's Play,'' which won its author, Charles Fuller, a Pulitzer Prize.

Born and raised in Harlem, Caesar joined the Navy after graduating from high school in 1952. He served as a hospital corpsman for five years before leaving the service to get a degree in dramatic arts from New York University.

He found work first as a voice-over announcer and then honed his acting skills in some of the nation's leading resident repertory companies including the Negro Ensemble Company. With that group, he acted in such productions as ''The River Niger,'' ''Square Root of the Soul'' and ''The Brownsville Raid.''

Mrs. Caesar, who married the actor in 1979, said every day began with acting.

''He was an actor's actor. He did his first play when he was 5. We woke up in the mornings with him warming his voice up with Shakespearean quotations. He had a phenomenal memory. He knew every Shakespearean play from 'King Lear' to 'As You Like It.'''

Other survivors include two daughters, Alex and Tiffany; a son, Justin; and a brother, Herbie.