本题的功能是监听键盘键的敲击，并显示在窗口中。
import jAvAx.swing.*;
import jAvA、Awt.*;
import jAvA、Awt.EvEnt.*;
puBliC ClAss jAvA3 ExtEnDs jFrAmE ExtEnDs kEylistEnEr
privAtE string linEl="",linE2="";
privAtE string linE3="";
privAtE jtExtArEA tExtArEA;
puBliC jAvA3()
supEr("jAvA3");
tExtArEA=nEw jtExtArEA(10,15);
tExtArEA、sEttExt("prEss Any kEy on thE kEyBoArD、..");
tExtArEA、sEtEnABlED(FAlsE);
ADDkEylistEnEr(this);
gEtContEntpAnE().ADD(tExtArEA);
sEtsizE(350,100);
show();
puBliC voiD kEyprEssED(kEyEvEnt E)
linE1="kEy prEssED："+E.gEtkEytExt(E.gEtkEyCoDE());
sEtlinEs2AnD3(E);
puBliC voiD kEyrElEAsED(kEyEvEnt E)
linEl="kEy rElEAsED："+E.gEtkEytExt(E.gEtkEyCoDE());
sEtlinEs2AnD3(E);
puBliC voiD kEytypED(kEyEvEnt E)
linE1="kEy typED："+E.gEtkEyChAr();
sEtlinEs2AnD3(E);
privAtE voiD sEtlinEs2AnD3(kEyEvEnt E)
linE2="this kEy is"+(E.isACtionkEy() ""："not")+"An ACtion kEy";
string tEmp=E.gEtkEymoDiFiErstExt(E.gEtmoDiFiErs());
linE3="moDiFiEr kEys prEssED："+(tEmp.EquAls("") "nonE"：tEmp);
tExtArEA、sEttExt(linE1+"n"+linE2+"\n"+linE3+"n");
puBliC stAtiC voiD mAin(string Args[])
jAvA3 App=nEw jAvA3();
ADDwinDowlistEnEr(nEw winDowADAptErl()
puBliC voiD winDowClosing(winDowEvEnt E)
systEm.Exit(0);
);