Lub tswv yim Java – Series III
Txheej txheem cej luam: Nyob rau hauv no 'Java Tswv yim' koob, Peb muaj mas ua haujlwm rau tus tes-on coding. Lub hom phiaj ntawm no yog pab kom koj to taub qhov tseeb thiab yuav siv cov lus uas koj nkag siab txog. Peb twb sim los npog ntau topics nrog coding piv txwv. Koj kuj yuav nyiam peb Java koob kuv thiab Java koob III
1) Yuav ua li cas zaub mov ib moos siv ib lub kua?
IB: Piv txwv muaj siv txoj hlua chav kawm ntawv thiab Calendar chav kawm ntawv rau zaub cov kua clock. Calendar hoob kawm muab tus nqi ntawm 'Teev', 'Feeb' thiab 'thib ob'.
import java.awt.*;
chaw nres nkoj nyoog.*;
chaw nres nkoj nyoog.*;
import java.awt.*;
ntshuam java.util.*;
Pej xeem hoob kawm ClockAplet extends kua dluab Runnable{
Xov,ntsaws;
pej xeem pib(){
= tshiab Thread(no);
pib();
}
pej xeem qhib(){
t1 = Thread.tam sim no();
Thaum(t1 = t = t=){
khaws cia();
sim{
pw tsaug zog(1000);
}
ntes(InterruptedException e){}
}
}
pej xeem tsis txhob mob(Nraaj g){
Calendar cal = tshiab GregorianCandar();
Txoj hlua xuab moos = Txoj hlua valuef(twj ywm..(COV SIJ HAWM ZOV ME NYUAM));
Txoj hlua feeb = Stringing.valuef(twj ywm..(Qhov tseeb...));
Txoj hlua thib ob = txoj hlua..(twj ywm..(Thib ob...));
g.g.drawString(Teev + “:” + feeb + “:” + thib ob, 20, 30);
}
}
Ntxiv dua thiab koj yuav tsum khiav lub kua hauv ib browser los yog kua saib xyuas cov zis.
2) Yuav tsim ib qho kev tshwm sim mloog hauv kua?
IB: Tom qab piv txwv li cov qauv qhia li cas yuav tsim ib kua yooj yim muaj khawm nyees khawm ntxiv & subtract ob tug lej. Txoj kev siv ntawm no yog addActionener () mloog ib qho kev tshwm sim(nyem rau ib khawm) & Khawm() tsim ib lub pob khawm.
chaw nres nkoj nyoog.*;
import java.awt.event.*;
import java.awt.*;
Pej xeem hoob kawm EventListeners extends kua
Txhim kho ActionListener{
Textarea txtarea;
Txoj hlua ntxiv, rho tawm;
rau cov menyuam kuv = 10, j = j= 20, lub caij ntuj sov =0,00;
pej xeem zam(){
txtarea = tshiab Textarea(10,20);
txtarea... setEditable(tsis tseeb);
ntxiv(txtArea,”Center”);
Khawm b = Button tshiab(“Ntxiv”);
Khawm c = Button tshiab(“rho tawm”);
b.addActionListener(no);
c.addActionener(no);
ntxiv(b);
ntxiv(c);
}
pej xeem yuav tsum tsis txhob ua(Kev Tshwm Sim){
Summ = kuv + j;
txtarea..setTex(“”);
txtarea.append(“Kuv = “+ Kuv + “\t” + “j = j= ” + j + “\n”);
Khawm tau qhov twg los = (Khawm)e.getsource();
Yog hais tias(qhov twg los...() == “Ntxiv”){
txtarea.append(“caij ntuj sov : ” + caij ntuj sov + “\n”);
}
Yog hais tias(Kuv >j){
Sub = kuv – j;
}
ntxiv{
Sub = j – Kuv;
}
Yog hais tias(qhov twg los...() == “rho tawm”){
txtarea.append(“subs : ” + subs + “\n”);
}
}
}
3) Yuav ua li cas qhib ib qhov rais tshiab siv kua?
IB: Qhov no piv txwv qhia li cas qhib ib webpage ntawm ib lub kua hauv lub qhov rais tshiab siv showDocument() txoj kev thib ob sib cav li “_blank” .
chaw nres nkoj nyoog.*;
import java.awt.*;
import java.net.*;
import java.awt.event.*;
Pej xeem kawm testURL_NewWindow ncua kua
Txhim kho ActionListener{
pej xeem zam(){
Hlua link_Text = “kaj siab lug”;
Khawm b = Button tshiab(link_Text);
b.addActionListener(no);
ntxiv(b);
}
pej xeem yuav tsum tsis txhob ua(Tshwm sim ntev){
Khawm tau qhov twg los = (Khawm)ae.getsource();
Kev txuas = “http://www.”+qhov twg los...()+”.com”;
sim {
Kua AppletContext ib = getapletcontex();
URL url = new URL(txuas);
ib tug showDocument (showDocument)(url,”_blank”);
}
ntes (Malformed MalformedLCEPtion e){
System.out.println(e.getMessage());
}
}
}
4) Yuav nyeem ib daim ntawv siv cov kua?
IB: Cov chaws hauv qab no snippet qha tau yuav nyeem ib daim ntawv siv ib cov kua siv kua qhib() txoj kev URL. Muaj ntau txoj kev nyeem ib kwj xws li buffered kwj, txheej buffered stream etc. Ntawm no peb tau siv buffered kwj dej nyeem cov ntaub ntawv.
chaw nres nkoj nyoog.*;
import java.awt.*;
ntshuam java.io.*;
import java.net.*;
Pej xeem hoob nyeem readFileapplet extends kua{
Kauj Ruam FileToRead = “kev ntsuam xyuas.txt”;
StringBuffer stringBuffer;
Textarea txtarea;
Nraaj g;
pej xeem zam(){
txtarea = tshiab Textarea(100, 100);
txtarea... setEditable(tsis tseeb);
ntxiv(txtArea, “Center”);
Txoj hlua prHtml = no.getParameter(“ntaub ntawv”);
Yog hais tias (prHtm != thov) Ntaub ntawv fileToRead = txoj hlua tshiab(prHtm);
nyeem ntawv();
}
pej xeem tsis txhob nyeem ntawv(){
txoj kab ntxwv;
URL url = nuj;
sim{
url = URL(tau txaiscodebase(), ntaub ntawv);
}
ntes(Malformed MalformedLCEPtion e){}
sim{
InputStream hauv = url.openStream();
BufferedReader bf = BufferedReader tshiab
(InputStreamReader tshiab(nyob rau hauv));
khoom = tshiab StringBuffer();
Thaum((= nyeem cov kab txheej txheem."()) != thov){
txawj txheem.append(kab + “\n”);
}
txtarea.append(“Tsev Neeg Lub Npe : ” + ntaub ntawv + “\n”);
txtarea.append(kauj ruam.toString());
}
ntes(IOException e){
e.printStackTrace();
}
}
}
5) Yuav ua li cas los tsim shapes siv kua?
IB: Qhov no piv txwv qhia li cas los tsim ib tug kua uas yuav muaj ib txoj kab, ib qho Oval & Ib Rectangle siv drawline(), twv txiaj() thiab kos() txoj kev Graphics class. Nyob rau hauv java Graphics hoob kawm yog lug siv los kos thiab cov neeg siv nyob rau hauv daim qauv, puas tsuaj.
chaw nres nkoj nyoog.*;
import java.awt.*;
Pej xeem hoob kawm Shapes extends kua{
int x=300,y=100,r=50;
pej xeem tsis txhob mob(Nraaj g){
g.g.kos(30,300,200,10);
g.g.drawOval(x-r,ntxaij,100,100);
g.g.kos(400,50,200,100);
}
}
Cov chaws saum toj no yuav ua rau cov nram qab no nyob rau hauv lub java enabled web browse
ib txoj kab, qee zaum & Ib Rectangle yuav tau twv hauv lub browser.
6) Yuav siv cov kua hauv JAVA?
IB: Viav vias yog ib qho tseem ceeb tivthaiv hauv java los ua UI interfaces. Cov viav vias no kuj siv hauv cov kua los ua cov neeg siv interface. Tom qab qauv qhia li cas yuav siv cov kua hauv JAVA los siv ActionListener & yog tsim JLabels.
import javax.swing.*;
chaw nres nkoj nyoog.*;
import java.awt.*;
import java.awt.event.*;
Pej xeem hoob kawm SApplet extends kua siv ActionListener {
TextField input,tso zis;
Daim ntawv lo lub hwj huam, daim ntawv lo;
Khawm 11;
Jlabel lb;
hauv nruab nrab, zaum = 0;
pej xeem zam(){
daim ntawv lo tshiab = tshiab(“naj npawb : “);
ntxiv(daim ntawv lo);
ntawv lo phem.setBackground(daj lug...);
ntawv lo phem.setForeground(magenta.magenta);
input = TextField(5);
ntxiv(tswv yim);
daim ntawv lo tshiab = tshiab(“caij ntuj sov : “);
ntxiv(daim ntawv lo);
label2.setBackground(daj lug...);
label2.setForeground(magenta.magenta);
tso zis = TextField(20);
ntxiv(tso zis);
b1 = khawm tshiab khawm(“Ntxiv”);
ntxiv(b1);
b1.addActionListener(no);
lbl = JLabel(“Piv txwv kua. “);
ntxiv(lws);
setBackground(daj lug...);
}
pej xeem yuav tsum tsis txhob ua(Tshwm sim ntev){
sim{
= Integer.parseint(tsis txaus siab...());
Lub caij ntuj sov number;
txheej txheem(“”);
setTex(Integer.toString(caij ntuj sov));
lblb.setForeground(xiav.xiav);
lbl.setTex(“Tso zis rau ob phau ntawv nyeem : ”
+ tso zis.taub hau());
}
ntes(NumberFormatception e){
lblb.setForeground(liab xim liab..);
lbl.setTex(“Invalid Entry!”);
}
}
}
7) Yuav sau ib daim ntawv uas siv kua?
IB: Nyob rau hauv cov piv txwv java text tau siv los sau tus neeg siv input. Tom qab nkag mus rau hauv lub input nws twb tau sau ntawv nyob rau hauv ib cov ntaub ntawv nyob rau hauv lawv cov ntaub ntawv hauv zos. Cov ntaub ntawv () tsim kom muaj cov ntaub ntawv.
ntshuam java.io.*;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import java.applet.kua;
import java.net.*;
Pej xeem hoob kawm WriteFile extends kua{
Button sau = khawm tshiab khawm(“Sau WriteFile (WriteToFile)”);
Daim ntawv lo rau ntawm daim ntawv lo tshiab =(“Nkag mus rau hauv lub npe:”);
TextField text = tshiab TextField(20);
Daim ntawv lo rau ntawm daim ntawv lo rau lub hwjchim tshiab(“Sau koj phau ntawv:”);
TextArea thaj tsam = tshiab Textarea(10,20);
pej xeem zam(){
ntxiv(daim ntawv lo);
ntawv lo phem.setBackground(xim lightray);
ntxiv(ntawv nyeem);
ntxiv(daim ntawv lo);
label2.setBackground(xim lightray);
ntxiv(Koog);
ntxiv(sau ntawv,BorderLayout CENTER);
sau.addAlistener(Actionlistener tshiab (){
pej xeem yuav tsum tsis txhob ua(Kev Tshwm Sim){
Sau ntawv tshiab();
}
}
);
}
Pej xeem cov hoob kawm {
Sau Ntawv Sau(){
sim {
Txoj hlua = text.getText();
Yog hais tias(sib npaug(“”)){
JoptionPane.showMesDiaTagesDialog(thov,
“Thov sau daim ntawv npe!”);
phau ntawv... thov kom muaj kev sib tham();
}
ntxiv{
Ntaub ntawv thov = Ntaub ntawv tshiab(str);
Yog hais tias(f.pheej tshwm sim()){
BufferedWriter tawm = tshiab
BufferedWriter(tshiab FileWriter(f,tseeb));
Yog hais tias(thaj chaw().qhov sib npaug(“”)){
JoptionPane.showMesDiaTagesDialog
(thov,”Thov sau koj phau ntawv!”);
thov...();
}
ntxiv{
out.Write(thaj chaw());
Yog hais tias(f.canwrite()){
JoptionPane.showMesDiaTagesDialog(thov,
“Cov ntawv nyeem yog sau rau hauv “+str);
phau ntawv nyeem.setTex(“”);
cheeb tsam(“”);
phau ntawv... thov kom muaj kev sib tham();
}
ntxiv{
JoptionPane.showMesDiaTagesDialog(thov,
“Phau ntawv tsis sau ntawv “+str);
}
out.close();
}
}
ntxiv{
JoptionPane.showMesDiaTagesDialog
(thov,”Cov ntaub ntawv tsis muaj nyob!”);
phau ntawv nyeem.setTex(“”);
phau ntawv... thov kom muaj kev sib tham();
}
}
}
ntes(Tshwj x x){
x.printStackTrace();
}
}
}
}
8) Yuav ua li cas thiaj sau tau cov zauv npaum li cas?
IB: Tom qab piv txwv qhia li cas ntxiv ua ntej tooj ntawm kev siv lub tswvyim ntawm teev tseg. Ntawm no cov txheej txheem static class siv los tuav cov zauv. Cov neeg muas zaub stackAddition () Txoj kev siv los ntxiv cov zauv ntxiv rau hauv lub tsho tiaj.
ntshuam java.io.IOException;
Pej xeem hoob kawm AdditionStack {
txheej;
txheeb cais;
Txheej Txheem Stack;
pej xeem tsis muaj dabtsis loj zoo li qub(Txoj hlua[] args) throws IOException {
naj npawb 50;
tshaaj plab();
System.out.println(“Lub caij ntuj sov.” + ib qho);
}
Pej xeem static void stackAddition() {
Lub plawv = Tshoj tshiab(10000);
ib yam twg = 0;
Thaum (num > 0)
{
Xovtooj khwb rho tawm(num);
–num;
}
Thaum (!Lub khwb rhuav tag())
{
Tshiab int newN = lub pop.pop();
ib tug tshiab;
}
}
}
Hoob Kawm {
qhov hauv maxSize;
ntiav[] cov ntaub ntawv;
ntiav;
Pej xeem Stack(nyob rau hauv) {
maxSize = s;
cov ntaub ntawv = tshiab[maxSize];
nyob saum toj kawg nka -1;
}
pej xeem tsis txhob raug thawb(hauv nkuaj) {
cov ntaub ntawv[++saum toj kawg n] = p;
}
pej xeem nyob hauv pop() {
cov ntaub ntawv rov qab[saum toj kawg n–];
}
pej xeem() {
cov ntaub ntawv rov qab[saum toj kawg n];
}
Pej xeem boolean ntxias() {
rov qab mus (sab saum toj = -1);
}
}
Cov chaws saum toj no yuav ua tau cov nram qab no.
Lub caij ntuj sov =1225
9) Yuav ua li cas thiaj tau tus thawj thiab lub caij kawg ntawm ib daim ntawv txuas?
IB: Tom qab piv txwv qhia li cas mus ua ntej thiab lub caij kawg ntawm ib daim ntawv txuas nrog rau kev pab los ntawm linkedlistname.getFirst() thiab linkedlistname.getLast() Hoob Kawm LinkedList. Tag nrho cov tuam txhab/queue/queue/deque haujlwm yuav yog yooj yim so tej ntsiab lus uas teev tseg. Tsuav yog nyob ntawm no feem ntau rau convenience, tab sis yog lawv yuav khiav ib nyuag sai dua li daim ntawv teev cov haujlwm.
chaw nres nkoj java..util.Linkedlist;
pej xeem hoob loj {
pej xeem tsis muaj dabtsis loj zoo li qub(Txoj hlua[] args) {
Linkedlist = tshiab Linkedlist();
lList.ntxiv(“100”);
lList.ntxiv(“200”);
lList.ntxiv(“300”);
lList.ntxiv(“400”);
lList.ntxiv(“500”);
System.out.println(“Thawj lub caij uas LinkedList yog :
” + lList.getFirst());
System.out.println(“Lub caij kawg ntawm LinkedList yog :
” + lList.getlast());
}
}
Cov chaws saum toj no yuav ua tau cov nram qab no.
Thawj lub caij uas LinkedList yog: 100
Lub caij kawg ntawm LinkedList yog: 500
10) Yuav ntxiv ib lub caij thaum xub thiab kawg txoj hauj lwm ntawm ib daim ntawv txuas?
IB: Tom qab piv txwv qhia li cas ntxiv rau ib lub caij thaum thawj thiab kawg txoj hauj lwm ntawm ib daim ntawv txuas los ntawm kev siv addFirst() thiab yus tus kheej() Txoj kev txuas ntawm daim ntawv teev Cov Hoob Kawm.
chaw nres nkoj java..util.Linkedlist;
pej xeem hoob loj {
pej xeem tsis muaj dabtsis loj zoo li qub(Txoj hlua[] args) {
Linkedlist = tshiab Linkedlist();
lList.ntxiv(“1”);
lList.ntxiv(“2”);
lList.ntxiv(“3”);
lList.ntxiv(“4”);
lList.ntxiv(“5”);
System.out.println(llist);
lList.addFirst(“0”);
System.out.println(llist);
lList.addlast(“6”);
System.out.println(llist);
}
}
Cov chaws saum toj no yuav ua tau cov nram qab no.
1, 2, 3, 4, 5
0, 1, 2, 3, 4, 5
0, 1, 2, 3, 4, 5, 6
