此題的Employee類設計有缺陷，缺少員工薪水的屬性。根據(jù)題意只能寫出下面的程序：
在始興等地區(qū)，都構建了全面的區(qū)域性戰(zhàn)略布局，加強發(fā)展的系統(tǒng)性、市場前瞻性、產(chǎn)品創(chuàng)新能力，以專注、極致的服務理念，為客戶提供網(wǎng)站設計、網(wǎng)站制作 網(wǎng)站設計制作按需定制,公司網(wǎng)站建設,企業(yè)網(wǎng)站建設,成都品牌網(wǎng)站建設,成都營銷網(wǎng)站建設,外貿(mào)營銷網(wǎng)站建設,始興網(wǎng)站建設費用合理。
abstract class Employee {
public abstract double earnings();
}
class YearWorker extends Employee {
@Override
public double earnings() {
return 0;
}
}
class MonthWorker extends Employee {
@Override
public double earnings() {
return 0;
}
}
class WeekWorker extends Employee {
@Override
public double earnings() {
return 0;
}
}
class Company {
Employee[] employee;
double salaries = 0;
Company(Employee[] employee) {
this.employee = employee;
}
public double salariesPay() {
salaries = 0;
//計算salaries
for(int i=0; iemployee.length; i++) {
salaries += employee[i].earnings();
}
return salaries;
}
}
public class HardWork {
public static void main(String[] args) {
Employee[] employee = new Employee[20];
for(int i=0; iemployee.length; i++) {
if(i % 3 == 0) {
employee[i] = new YearWorker();
}
else if(i % 3 == 1) {
employee[i] = new MonthWorker();
}
else if(i % 3 == 2) {
employee[i] = new WeekWorker();
}
}
Company company = new Company(employee);
System.out.println("公司年工資總額:" + company.salariesPay());
}
}
運行結果：
公司年工資總額:0.0
給你個做好了的Java的源程序的記事本，自己看看就行了的，不怎么難的···
import java.awt.*;
import java.awt.event.*;
import java.io.*;
import javax.swing.*;
public class MyNotepad implements ActionListener{
private JFrame frame=new JFrame("新記事本");
private JTextArea jta=new JTextArea();
private String result="";
private boolean flag=true;
private File f;
private JButton jb=new JButton("開始");
private JTextField jtf=new JTextField(15);
private JTextField jt=new JTextField(15);
private JButton jbt=new JButton("替換為");
private JButton jba=new JButton("全部替換");
private Icon ic=new ImageIcon("D:\\java課堂筆記\\GUI\\11.gif");
private String value;
private int start=0;
private JFrame jf=new JFrame("查找");
private JFrame jfc=new JFrame("替換");
@Override
public void actionPerformed(ActionEvent e) {
String comm=e.getActionCommand();
if("新建".equals(comm)){
if(!(frame.getTitle().equals("新記事本"))){
if(!flag){
write();
newNew();
}else{
JFileChooser jfc=new JFileChooser("D:\\java課堂筆記");
int returnVal = jfc.showDialog(null,"保存為");
if(returnVal == JFileChooser.APPROVE_OPTION) {//選擇文件后再執(zhí)行下面的語句，保證了程序的健壯性
f=jfc.getSelectedFile();
flag=false;
write();
}
}
}else if(!(jta.getText().isEmpty())){
JFileChooser jfc=new JFileChooser("D:\\java課堂筆記");
int returnVal = jfc.showDialog(null,"保存為");
if(returnVal == JFileChooser.APPROVE_OPTION) {//選擇文件后再執(zhí)行下面的語句，保證了程序的健壯性
f=jfc.getSelectedFile();
flag=false;
write();
newNew();
}
}else{
newNew();
}
}else if("打開".equals(comm)){
JFileChooser jfc=new JFileChooser("D:\\java課堂筆記");
jfc.setDialogType(JFileChooser.OPEN_DIALOG);
int returnVal = jfc.showOpenDialog(null);
if(returnVal == JFileChooser.APPROVE_OPTION) {//選擇文件后再執(zhí)行下面的語句，保證了程序的健壯性
f=jfc.getSelectedFile();
frame.setTitle(f.getName());
result=read();
flag=false;
value=result;
jta.setText(result);
}
}else if("保存".equals(comm)){
JFileChooser jfc=new JFileChooser("D:\\java課堂筆記");
if(flag){
int returnVal = jfc.showDialog(null,"保存為");
if(returnVal == JFileChooser.APPROVE_OPTION) {//選擇文件后再執(zhí)行下面的語句，保證了程序的健壯性
f=jfc.getSelectedFile();
flag=false;
write();
}
}else{
write();
}
}else if("另存".equals(comm)){
JFileChooser jfc=new JFileChooser("D:\\java課堂筆記");
int returnVal = jfc.showDialog(null,"另存");
if(returnVal == JFileChooser.APPROVE_OPTION) {//選擇文件后再執(zhí)行下面的語句，保證了程序的健壯性
f=jfc.getSelectedFile();
write();
}
}else if("退出".equals(comm)){
System.exit(0);
}else if("撤銷".equals(comm)){
jta.setText(value);
}else if("剪切".equals(comm)){
value=jta.getText();
jta.cut();
}else if("復制".equals(comm)){
jta.copy();
}else if("粘貼".equals(comm)){
value=jta.getText();
jta.paste();
}else if("刪除".equals(comm)){
value=jta.getText();
jta.replaceSelection(null);
}else if("全選".equals(comm)){
jta.selectAll();
}else if("查找".equals(comm)){
value=jta.getText();
jf.add(jtf,BorderLayout.CENTER);
jf.add(jb,BorderLayout.SOUTH);
jf.setLocation(300,300);
jf.pack();
jf.setVisible(true);
jf.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
}else if("替換".equals(comm)){
value=jta.getText();
GridLayout gl=new GridLayout(3,3);
JLabel jl1=new JLabel("查找內(nèi)容:");
JLabel jl2=new JLabel("替換為:");
jfc.setLayout(gl);
jfc.add(jl1);
jfc.add(jtf);
jfc.add(jb);
jfc.add(jl2);
jfc.add(jt);
jfc.add(jbt);
JLabel jl3=new JLabel();
JLabel jl4=new JLabel();
jfc.add(jl3);
jfc.add(jl4);
jfc.add(jba);
jfc.setLocation(300,300);
jfc.pack();
jfc.setVisible(true);
jfc.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
}else if("版本".equals(comm)){
JDialog jd=new JDialog(frame,"關于對話框");
jd.setSize(200,200);
JLabel l=new JLabel("哈哈哈哈哈哈哈哈哈哈呵呵呵呵呵呵呵呵呵呵呵呵呵");
jd.add(l,BorderLayout.CENTER);
jd.setLocation(100,200);
jd.setSize(300,300);
jd.setVisible(true);
// jd.pack();
jd.setDefaultCloseOperation(JDialog.DISPOSE_ON_CLOSE);
}else if("開始".equals(comm)||"下一個".equals(comm)){
String temp=jtf.getText();
int s=value.indexOf(temp,start);
if(value.indexOf(temp,start)!=-1){
jta.setSelectionStart(s);
jta.setSelectionEnd(s+temp.length());
jta.setSelectedTextColor(Color.GREEN);
start=s+1;
jb.setText("下一個");
// value=value.substring(s+temp.length());//不能截取字串
}else {
JOptionPane.showMessageDialog(jf, "查找完畢!", "提示", 0, ic);
jf.dispose();
}
}else if("替換為".equals(comm)){
String temp=jtf.getText();
int s=value.indexOf(temp,start);
if(value.indexOf(temp,start)!=-1){
jta.setSelectionStart(s);
jta.setSelectionEnd(s+temp.length());
jta.setSelectedTextColor(Color.GREEN);
start=s+1;
jta.replaceSelection(jt.getText());
}else {
JOptionPane.showMessageDialog(jf, "查找完畢!", "提示", 0, ic);
jf.dispose();
}
}else if("全部替換".equals(comm)){
String temp=jta.getText();
temp=temp.replaceAll(jtf.getText(), jt.getText());
jta.setText(temp);
}
}
public String read(){
String temp="";
try {
FileInputStream fis = new FileInputStream(f.getAbsolutePath());
byte[] b=new byte[1024];
while(true){
int num=fis.read(b);
if(num==-1)break;
temp=temp+new String(b,0,num);
}
fis.close();
} catch (Exception e1) {
e1.printStackTrace();
}
return temp;
}
public void write(){
try {
FileOutputStream fos=new FileOutputStream(f);
fos.write(jta.getText().getBytes());
fos.close();
} catch (Exception e) {
e.printStackTrace();
}
}
public void newNew(){
frame.dispose();
new MyNotepad();
flag=true;
}
public MyNotepad(){
JMenuBar jmb=new JMenuBar();
String[] menuLab={"文件","編輯","幫助"};
String[][] menuItemLab={{"新建","打開","保存","另存","退出"},
{"撤銷","剪切","復制","粘貼","刪除","全選","查找","替換"},
{"版本"}};
for(int i=0;imenuLab.length;i++){
JMenu menu=new JMenu(menuLab[i]);
jmb.add(menu);
for(int j=0;jmenuItemLab[i].length;j++){
JMenuItem jmi=new JMenuItem(menuItemLab[i][j]);
menu.add(jmi);
jmi.addActionListener(this);
}
}
frame.setJMenuBar(jmb);
jta.setLineWrap(true);//自動換行
JScrollPane jsp=new JScrollPane(jta);//滾動窗口面板
frame.add(jsp);
jb.addActionListener(this);
jbt.addActionListener(this);
jba.addActionListener(this);
frame.setLocation(200,50);
frame.setSize(620,660);
frame.setVisible(true);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
public static void main(String[] args) {
new MyNotepad();
}
}
class Car
{
// 車輛屬性
private String brand; // 品牌
private double engineDisplacement;// 排氣量
private double speed;// 當前速度
private boolean status;// 啟動狀態(tài)
private double maxSpeed;// 最大速度
public double getSpeed () {
return this.speed;
}
public Car(String brand, double engineDisplacement, double maxSpeed) {
this.brand = brand;
this.engineDisplacement = engineDisplacement;
this.maxSpeed = maxSpeed;
// 其他屬性也要有初始值，不然執(zhí)行出錯。
this.speed = 0;
this.status = false;
}
/** 啟動 */
public void start() {
this.status = true;
printNowStatus ();
}
/** 關閉（熄火） */
public void stop() {
// 只在速度為0時關閉（貌似樓上兩位沒仔細看題…）
if (this.speed == 0)
{
this.status = false;
}
printNowStatus ();
}
/** 加速 */
public void speedUp() {
// 只在啟動時可以加速
if (this.status)
{
this.speed = this.speed + 20;
if (this.speed this.maxSpeed)
{
this.speed = this.maxSpeed;
}
}
printNowStatus ();
}
/** 減速 */
public void slowDown() {
// 只在啟動時可以減速
if (this.status)
{
this.speed = this.speed - 10;
if (this.speed 0)
{
this.speed = 0;
}
}
printNowStatus ();
}
/** 狀態(tài)打印，在每次啟動，加減速，關閉時調(diào)用 */
private void printNowStatus () {
System.out.println("轎車【" + this.brand + "】現(xiàn)在的啟動狀態(tài)是：" + this.status + "速度是：" + this.speed +"。");
}
}
public class TestCar
{
public static void main(String[] args)
{
Car myCar = new Car ("紅旗", 2, 120);
//啟動
myCar.start();
// 循環(huán)加速到120
while (myCar.getSpeed() 120)
{
myCar.speedUp();
}
//循環(huán)減速
while (myCar.getSpeed() 0)
{
myCar.slowDown();
}
//關閉
myCar.stop();
}
}
/* 直接拿文本寫的，我用的電腦沒裝jdk，樓主自己到Java開發(fā)環(huán)境下調(diào)試，應該沒什么問題… */
相當于：System.out.println(test.f());
因為b=a=f();此時的f()已經(jīng)被子類B重寫，所以b=a=f()=2。
即使這么寫也是2：
A test = new B();
System.out.println(test.a);
同樣，相當于：System.out.println(test.f());
這種情況就是多態(tài)了??！
class NoLowerLetterException extends Exception {
public NoLowerLetterException(String msg) {
super(msg);
}
}
class NoDigitException extends Exception {
public NoDigitException(String msg) {
super(msg);
}
}
class People {
void printLetter(char c) {
if (c = 'a' c = 'z') {
System.out.println(c);
} else {
try {
throw new NoLowerLetterException(String.valueOf(c));
} catch (NoLowerLetterException e) {
e.printStackTrace();
}
}
}
void printDigit(char c) {
if (c = '0' c = '9') {
System.out.println(c);
} else {
try {
throw new NoDigitException(String.valueOf(c));
} catch (NoDigitException e) {
e.printStackTrace();
}
}
}
}
public class ExceptionExample {
public static void main(String args[]) {
People people = new People();
for (int i = 0; i 128; i++) {
// 【代碼5】
// //將i轉(zhuǎn)換為char類型，執(zhí)行people.printLetter()方法，如果出現(xiàn)異常則捕獲，并輸出異常的錯誤信息！
people.printLetter((char) i);
}
for (int i = 0; i 128; i++) {
// 【代碼6】 //將i轉(zhuǎn)換為char類型，執(zhí)行people. printDigit
// ()方法，如果出現(xiàn)異常則捕獲，并輸出異常的錯誤信息！
people.printDigit((char) i);
}
}
}
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class Painter extends JFrame{
/**
*
*/
private static final long serialVersionUID = 8160427604782702376L;
CanvasPanel canvas = new CanvasPanel();;
public Painter() {
super("Star");
this.add(canvas);
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
this.pack();
this.setResizable(false);
this.setLocationRelativeTo(null);
this.setVisible(true);
}
public static void main(String[] args) {
new Painter();
}
}
class CanvasPanel extends JPanel implements ActionListener{
/**
*
*/
private static final long serialVersionUID = -4642528854538741028L;
private JButton[] btn = new JButton[4];
private String[] btn_name = {"+", "-", "R", "L"};
private int center_x = 200, center_y = 200, radius = 100, degree = 0;
public CanvasPanel() {
this.setPreferredSize(new Dimension(400, 500));
this.setLayout(null);
for(int i = 0; i 4; i++) {
btn[i] = new JButton(btn_name[i]);
btn[i].setBounds(160 + i * 60, 425, 50, 50);
btn[i].addActionListener(this);
this.add(btn[i]);
}
}
@Override
public void paintComponent(Graphics g) {
super.paintComponent(g);
for(int i = 0; i 5; i++) {
g.drawLine( (int) (center_x + radius * Math.sin(Math.toRadians(degree + 72 * i))),
(int) (center_y - radius * Math.cos(Math.toRadians(degree + 72 * i))),
(int) (center_x + radius * Math.sin(Math.toRadians(degree + 72 * i + 144))),
(int) (center_y - radius * Math.cos(Math.toRadians(degree + 72 * i + 144))));
}
}
public void actionPerformed(ActionEvent e) {
// TODO Auto-generated method stub
if(e.getActionCommand() == "+") {
if(radius 200)
radius += 2;
repaint();
} else if(e.getActionCommand() == "-") {
if(radius 0)
radius -= 2;
repaint();
} else if(e.getActionCommand() == "R") {
degree = (degree + 2) % 360;
repaint();
} else if(e.getActionCommand() == "L") {
degree = (degree - 2) % 360;
repaint();
}
}
}
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