TAIPEI, Taiwan — Lin Fei-fan led the charge nearly three years ago when hundreds of students occupied Taiwan’s legislature to protest a trade deal with China. With the island’s economy increasingly tied to the mainland’s, and Beijing’s global influence on the rise, he worried that Taiwan’s independence was at stake — and might be a lost cause.

Now, thanks to a couple of sentences uttered by Donald J. Trump on a talk show, Mr. Lin has new hope.

The president-elect stunned the world on Sunday by suggesting he might abandon the One China principle, the bedrock understanding under which the United States established relations with Beijing and cut official ties with Taiwan nearly four decades ago. His apparent willingness to rethink longstanding American policy that prioritizes China over Taiwan has energized Mr. Lin, 28, and many like him. But it has also left them anxious, and asking:

What does it mean for one’s homeland to be put on the table by Mr. Trump, an inveterate deal maker, in negotiations with China’s Communist leaders, who are not known for making concessions easily?

“Many people in Taiwan worry that once Trump takes office, he’ll make a U-turn,” Mr. Lin said. “We are suspicious of his motivations.”