jt.append(s);
參考：
public?void?append(String?str)
Appends?the?given?text?to?the?end?of?the?document.?Does?nothing?if?the?model?is?null?or?the?string?is?null?or?empty.
Parameters:
str?-?the?text?to?insert
See?Also:
insert(java.lang.String,?int)