问为什么"toString“会给出与JFrame和System.out.println不同的结果？

EN

public class Main {
public static void main(String[] args){
    File file = new File("1.txt");
    try {
        file.createNewFile();
    } catch (IOException e) {
        e.printStackTrace();
    }
    StringBuilder result = new StringBuilder();
    try (InputStreamReader reader = new InputStreamReader(new FileInputStream(file), StandardCharsets.UTF_8)){
        int a = reader.read();
        while(a!=-1){
            result.append((char)a);
            a = reader.read();
        }
    } catch (Exception e) {
        e.printStackTrace();
    }

    JFrame frame = new JFrame(result.toString());
    frame.setVisible(true);
    frame.setSize(500, 500);

    System.out.println(result.toString());
}
}