public class Mtttt {

    DateTime t1;
    static transient DateTime t2;

    public String getT1() {
        if (t1 == null) t1 = System.now();
        return '' + t1;
    }

    public String getT2() {
        if (t2 == null) t2 = System.now();
        return '' + t2;
    }
}