public class User {

    private int id;

    private String name;

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }
}
 

public static void main(String[] args) {
        User user = new User();
        String name = user.getName()==null ? "--- ---":user.getName();
        System.out.println(name);
    }

意思是：user的屬性name等於null的話，String name的值就為

--- ---
不然就是user.getName()