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你也不说计算公式，不知道怎么计算，我去网上找了一个月支付款的计算公式，不知道和你题目的要求是否一样，如果不一样你就改下公式就行。
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java代码如下：
public class Loan {
public static void main(String[] args){
double rate ;//利率
int year ; //年数
double money ; //贷款总额
double monthpay ;//月付款
Scanner sc = new Scanner(System.in);
System.out.println("输入月利率：");
rate = sc.nextDouble();
System.out.println("输入年数：");
year = sc.nextInt();
System.out.println("输入贷款总额：");
money = sc.nextDouble();
//计算月付款
monthpay = (money * rate)/Math.abs(1 - (1 / (1 + rate ) * year * 12 ));
System.out.println("每月应该还贷款：" + monthpay);
}
}
package entity;
public class Market {
private int id;//id
private int num;//数量
private String goods;//商品
private double price;//价格
public Market(int id, int num, String goods, double price) {
super();
this.id = id;
this.num = num;
this.goods = goods;
this.price = price;
}
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public int getNum() {
return num;
}
public void setNum(int num) {
this.num = num;
}
public String getGoods() {
return goods;
}
public void setGoods(String goods) {
this.goods = goods;
}
public double getPrice() {
return price;
}
public void setPrice(double price) {
this.price = price;
}
public double calc( ){
double sum=price*num;
System.out.println("您消费共计："+sum+"￥");
return sum;
}
}
package test;
import java.util.HashMap;
import java.util.Map;
import java.util.Scanner;
import entity.Market;
public class Test {
private static MapInteger,Market goods=new HashMapInteger, Market();
public static void main(String[] args) {
System.out.println("-------超市计价系统-------");
String goods1="可口可乐";
String goods2="爆米花";
String goods3="益达";
printTable("编号","商品","价格");
printTable("1",goods1,"3.0￥");
printTable("2",goods2,"5.0￥");
printTable("3",goods3,"10.0￥");
goods.put(1, new Market(1, 1, goods1, 3.0));
goods.put(2, new Market(2, 1, goods2, 5.0));
goods.put(3, new Market(3, 1, goods3, 10.0));
Scanner input = new Scanner(System.in);
System.out.println("请输入商品的编号:");
int num = input.nextInt();
System.out.println("请输入商品的数量");
int amount = input.nextInt();
Market market = goods.get(num);
market.setNum(amount);
market.calc();
}
private static void printTable(String row1,String row2,String row3 ) {
System.out.print(row1);
int times=12;
if (row2!="商品") {
times=5;
}
for (int i = 0; i times; i++) {
System.out.print(" ");
}
System.out.print(row2);
for (int i = 0; i 10; i++) {
System.out.print(" ");
}
System.out.print(row3);
System.out.println("\n");
}
}
//测试结果：
-------超市计价系统-------
编号 商品 价格
1 可口可乐 3.0￥
2 爆米花 5.0￥
3 益达 10.0￥
请输入商品的编号:
3
请输入商品的数量
5
您消费共计：50.0￥
学java的时候自己编的，很简单，能够连续输入计算式后进行计算
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.FlowLayout;
import java.awt.Font;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.text.NumberFormat;
import java.util.ArrayList;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JTextField;
/**简易计算器，能够进行简单的计算
*
* @see 2008.12.9
*/
public class CalculatorA
implements ActionListener{
private JFrame frame;
private JTextField field;
private JButton[] allButtons;
private JButton clearButton;
// private JButton backButton;
String result="";//保存结果
StringBuilder sb = new StringBuilder();//保存要进行的计算式
int x = 0; //用来判断上一次的事件类型
String str = "123+456-789*0.=/";
ArrayListString arrayList = new ArrayListString();//保存计算式，通过方法进行运算
public CalculatorA(){
frame = new JFrame("我的计算器v1.1");
frame.setLocation(300,300);
field = new JTextField(25);
allButtons = new JButton[16];
for(int i=0;iallButtons.length;i++){
allButtons[i]= new JButton(str.substring(i,i+1));
}
clearButton = new JButton("CLEAR");
// backButton = new JButton("——");
init();
setFondAndColor();
addEventHander();
}
public void init(){
frame.setLayout(new BorderLayout());
JPanel northPanel = new JPanel();
JPanel centerPanel = new JPanel();
JPanel southPanel = new JPanel();
northPanel.setLayout(new FlowLayout());
centerPanel.setLayout(new GridLayout(4,4));
southPanel.setLayout(new FlowLayout());
northPanel.add(field);
for(int i=0;iallButtons.length;i++){
centerPanel.add(allButtons[i]);
}
southPanel.add(clearButton);
//southPanel.add(backButton);
frame.add(northPanel,BorderLayout.NORTH);
frame.add(centerPanel,BorderLayout.CENTER);
frame.add(southPanel,BorderLayout.SOUTH);
}
//设置输入字体
public void setFondAndColor(){
field.setFont(new Font("宋体",Font.BOLD,24));
field.setBackground(new Color(100,200,200));
field.setForeground(Color.RED);
//设置字体从右起始
field.setHorizontalAlignment(JTextField.RIGHT);
}
public void showMi(){
frame.pack();
frame.setResizable(false);
frame.setVisible(true);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
public void addEventHander(){
for(int i=0;iallButtons.length;i++){
allButtons[i].addActionListener(this);
}
clearButton.addActionListener(this);
// backButton.addActionListener(this);
}
@Override
public void actionPerformed(ActionEvent e) {
String str = e.getActionCommand();//取得当前事件返回的值
if("0123456789.".indexOf(str)!=-1){
if(x == 0){ //当x为0时表示还没有进行输入
result=str;
sb.append(str);
field.setText(str);
x = 1;
}
else if(x == 1){
result = result +str;
sb.append(str);
field.setText(result);
x = 1;
}
else if(x == 2){
sb.delete(0,sb.length());
result = result+str;
sb.append(str);
field.setText(result);
x = 1;
}
else if(x == 3){
result = str;
sb.delete(0,sb.length());
arrayList.clear();
field.setText(str);
sb.append(str);
field.setText(str);
x = 1;
}
else if(x == 4){
result ="";
sb.delete(0,sb.length());
arrayList.clear();
result = str;
sb.append(str);
field.setText(str);
x = 1;
}
else{
result = result +str;
sb.append(str);
field.setText(result);
x = 1;
}
}
else if("+*-/".indexOf(str)!=-1){
if(x == 0){
field.setText("");
x = 2;
}
else if(x == 1){
result = result + str;
arrayList.add(sb.toString());
arrayList.add(str);
sb.append(str);
field.setText(result);
x = 2;
}
else if(x == 2){
x = 2;
}
else if(x == 3){
field.setText(result+str);
arrayList.add(result);
arrayList.add(str);
result = result+str;
x = 2;
}
else if(x == 4){
result ="";
sb.delete(0,sb.length());
arrayList.clear();
x = 2;
}
else{
field.setText(result+str);
arrayList.add(result);
arrayList.add(str);
result = result+str;
x = 2;
}
}
else if("=".equals(str)){
if(x == 0){
field.setText("0");
arrayList.clear();
result = "0";
x = 3;
}
else if(x == 1){
try{
arrayList.add(sb.toString());
arrayList = getResult(arrayList);
result = arrayList.get(0);
field.setText(result);
arrayList.clear();
x = 3;
}catch(Exception e1){
field.setText("数据格式异常");
x = 0;
}
}
else if(x == 2){
field.setText("数据格式错误.....");
arrayList.clear();
x = 0;
}
else if(x == 3){
field.setText(result);
x = 3;
}
else if(x == 4){
result ="";
sb.delete(0,sb.length());
arrayList.clear();
x = 3;
}
else {
try{
arrayList.add(sb.toString());
arrayList = getResult(arrayList);
result = arrayList.get(0);
field.setText(result);
arrayList.clear();
x = 3;
}catch(Exception e1){
field.setText("数据格式异常");
x = 0;
}
}
}
else if("CLEAR".equals(str)){
arrayList.clear();
field.setText("0");
arrayList.add("0");
x = 4;
}
else{
if(result.length()1){
result = result.substring(0,result.length()-1);
if(sb.length()0){
sb.delete(sb.length()-1,sb.length());
}
else {
sb.delete(0,1);
}
field.setText(result);
x = 5;
}
else{
result = "";
sb.delete(0,sb.length());
arrayList.clear();
field.setText("0");
x = 0;
}
}
}
public static ArrayListString getResult(ArrayListString list){
String res = null;
String[] s = {"/","*","-","+"};
int i=0;
if(list.size()1){
for(;is.length;){
if(s[i].equals("/")){
for(int j=0;jlist.size();j++){
if(list.get(j).equals(s[i])){
res = Double.toString(Double.parseDouble(list.get(j-1))/Double.parseDouble(list.get(j+1)));
//本地的数据格式
NumberFormat nf = NumberFormat.getInstance();
res = nf.format(Double.parseDouble(res));
res = getChange(res);
list.set(j-1,res);
list.remove(j);
list.remove(j);
getResult(list);
}
}
i++;
}
else if(s[i].equals("*")){
for(int j=0;jlist.size();j++){
if(list.get(j).equals(s[i])){
res = Double.toString(Double.parseDouble(list.get(j-1))*Double.parseDouble(list.get(j+1)));
NumberFormat nf = NumberFormat.getInstance();
res = nf.format(Double.parseDouble(res));
res = getChange(res);
list.set(j-1,res);
list.remove(j);
list.remove(j);
getResult(list);
}
}
i++;
}
else if(s[i].equals("-")){
for(int j=0;jlist.size();j++){
if(list.get(j).equals(s[i])){
res = Double.toString(Double.parseDouble(list.get(j-1))-Double.parseDouble(list.get(j+1)));
NumberFormat nf = NumberFormat.getNumberInstance();
res = nf.format(Double.parseDouble(res));
res = getChange(res);
list.set(j-1,res);
list.remove(j);
list.remove(j);
getResult(list);
}
}
i++;
}
else {
for(int j=0;jlist.size();j++){
if(list.get(j).equals(s[i])){
res = Double.toString(Double.parseDouble(list.get(j-1))+Double.parseDouble(list.get(j+1)));
NumberFormat nf = NumberFormat.getInstance();
res = nf.format(Double.parseDouble(res));
res = getChange(res);
list.set(j-1,res);
list.remove(j);
list.remove(j);
getResult(list);
}
}
i++;
}
}
}
return list;
}
//对数字字符串进行排除不必要符号
public static String getChange(String res){
String s_temp = "";
char[] c = new char[res.length()];
for(int k=0;kc.length;k++){
c[k] = res.charAt(k);
}
for(int k=0;kc.length;k++){
if((c[k]= '0' c[k]= '9')|| c[k] == '.'){
s_temp += c[k];
}
}
return s_temp;
}
public static void main(String[] args){
new CalculatorA().showMi();
}
}
import java.util.*;
class ThreadTest {
static int type = 4, num = 10; //定义资源数目和线程数目
static int[] resource = new int[type]; //系统资源总数
//static int[] copyResource = new int[type]; //副本
static Random rand = new Random();
static Bank[] bank = new Bank[num]; //线程组
Bank temp = new Bank();
public void init() {
//初始化组中每个线程，随机填充系统资源总数
for(int i = 0; i type; i++)
resource[i] = rand.nextInt(10) + 80;
System.out.print("Resource:");
for(int i = 0; i type; i++)
System.out.print(" " + resource[i]);
System.out.println("");
for(int i = 0; i bank.length; i++)
bank[i] = new Bank("#" + i);
}
public ThreadTest4() {
init();
}
class Bank extends Thread {
//银行家算法避免死锁
public int[]
max = new int[type], //总共需求量
need = new int[type], //尚需资源量
allocation = new int[type]; //已分配量
private int[]
request = new int[type], //申请资源量
copyResource = new int[type]; //资源副本
private boolean isFinish = false; //线程是否完成
int[][] table = new int[bank.length][type*4]; //二维资源分配表
private void init() {
// 随机填充总共、尚需、已分配量
synchronized(resource) {
for(int i = 0; i type; i++) {
max[i] = rand.nextInt(5) + 10;
need[i] = rand.nextInt(10);
allocation[i] = max[i] - need[i];
resource[i] -= allocation[i]; //从系统资源中减去已分配的
}
printer();
for(int i = 0; i type; i++) {
if(resource[i] 0) {
//若出现已分配量超出系统资源总数的错误则退出
System.out.println("The summation of Threads' allocations is out of range!");
System.exit(1);
}
}
}
}
public Bank(String s) {
setName(s);
init();
start();
}
public Bank() {
//none
}
public void run() {
try {
sleep(rand.nextInt(2000));
}
catch(InterruptedException e) {
throw new RuntimeException(e);
}
while(true) {
//程序没有完成时一直不断申请资源
if(askFor() == false) {
try {
sleep(1000);
}
catch(InterruptedException e) {
throw new RuntimeException(e);
}
}
else
tryRequest();
if(noNeed() == true)
break;
}
//休眠一段时间模拟程序运行
try {
sleep(1000);
}
catch(InterruptedException e) {
throw new RuntimeException(e);
}
System.out.println(getName() + " finish!");
synchronized(resource) {
//运行结束释放占有资源
for(int i = 0; i type; i++) {
resource[i] += allocation[i];
need[i] = allocation[i] = max[i] = 0;
}
}
}
private void printer() {
//打印当前资源信息
System.out.print(getName() + " Max:");
for(int i = 0; i type; i++)
System.out.print(" " + max[i]);
System.out.print(" Allocation:");
for(int i = 0; i type; i++)
System.out.print(" " + allocation[i]);
System.out.print(" Need:");
for(int i = 0; i type; i++)
System.out.print(" " + need[i]);
System.out.print(" Available:");
for(int i = 0; i type; i++)
System.out.print(" " + resource[i]);
System.out.println("");
}
private boolean askFor() {
//随机产生申请资源量并检测是否超标
boolean canAsk = false;
for(int i = 0; i type; i++) {
request[i] = rand.nextInt(20);
//防止申请量超过所需量
if(request[i] need[i])
request[i] = need[i];
}
for(int i = 0; i type; i++) //防止随机申请资源全为0
if(request[i] 0)
canAsk = true;
synchronized(resource) {
//锁住可供资源检查是否超标
for(int i = 0; i type; i++) {
if(request[i] resource[i])
//如果申请资源超过可供资源则等待一段时间后重新申请
return false;
}
}
return canAsk;
}
private void tryRequest() {
//创建副本尝试分配请求
synchronized(resource) {
for(int i = 0; i type; i++)
//依然要防止请求量超出范围
if(request[i] resource[i])
return;
for(int i = 0; i type; i++) {
//复制资源量并减去需求量到一个副本上
copyResource[i] = resource[i];
copyResource[i] -= request[i];
}
System.out.print(getName() + " ask for:");
for(int i = 0; i type; i++)
System.out.print(" " + request[i]);
System.out.println("");
if(checkSafe() == true) {
//如果检查安全则将副本值赋给资源量并修改占有量和需求量
for(int i = 0; i type; i++) {
resource[i] = copyResource[i];
allocation[i] += request[i];
need[i] -= request[i];
}
System.out.println(getName() + " request succeed!");
}
else
System.out.println(getName() + " request fail!");
}
}
private boolean checkSafe() {
//银行家算法检查安全性
synchronized(bank) {
//将线程资源信息放入二维资源分配表检查安全性，0~type可用资源／type~type*2所需资源／type*2~type*3占有资源／type*3~-1可用+占用资源
for(int i = 0; i bank.length; i++) {
for(int j = type; j type*2; j++) {
table[i][j] = bank[i].need[j%type];
}
for(int j = type*2; j type*3; j++) {
table[i][j] = bank[i].allocation[j%type];
}
}
//冒泡排序按需求资源从小到大排
for(int i = 0; i bank.length; i++) {
for(int j = i; j bank.length-1; j++) {
sort(j, 4);
}
}
//进行此时刻的安全性检查
for(int i = 0; i type; i++) {
table[0][i] = copyResource[i];
table[0][i+type*3] = table[0][i] + table[0][i+type*2];
if(table[0][i+type*3] table[1][i+type])
return false;
}
for(int j = 1; j bank.length-1; j++) {
for(int k = 0; k type; k++) {
table[j][k] = table[j-1][k+type*3];
table[j][k+type*3] = table[j][k] + table[j][k+type*2];
if(table[j][k+type*3] table[j+1][k+type])
return false;
}
}
}
return true;
}
private void sort(int j, int k) {
//递归冒泡排序
int tempNum;
if(table[j][k] table[j+1][k]) {
for(int i = type; i type*2; i++) {
tempNum = table[j][i];
table[j][i] = table[j+1][i];
table[j+1][i] = tempNum;
}
/*temp = bank[j];
bank[j] = bank[j+1];
bank[j+1] = temp;*/
}
else if(table[j][k] == table[j+1][k] k type*2) //此资源量相同时递归下一个资源量排序并且防止超出范围
sort(j, k+1);
}
private boolean noNeed() {
//是否还需要资源
boolean finish = true;
for(int i = 0; i type; i++) {
if(need[i] != 0) {
finish = false;
break;
}
}
return finish;
}
}
public static void main(String[] args) {
ThreadTest t = new ThreadTest();
//后台线程，设定程序运行多长时间后自动结束
new Timeout(30000, "---Stop!!!---");
}
}
public interface ITransfer{ /* * 银行内部转账,从转出账号中扣除转账金额,给转入账号增加转账金额,需要保证以上两个操作 * 要么同时成功,要么同时失败 * fromAccountId 转出账号 * outAccountId 转入账号 * amount 转账金额 */ public void transferInner(String fromAccountId,String outAccountId,BigDecimal amount); /* * 外部转账-转出,从转出账号中扣除转账金额 * fromAccoutnId 转出账号 * amount 转账金额 */ public void transferOut(String fromAccountId,String outAccountId,BigDecimal amount); /* * 外部转账-转入,从转入账号中增加转账金额 * toAccoutnId 转出账号 * amount 转账金额 */ public void transerIn(String toAccountId,BigDecimal amount); } public interface ITransfer{ /* * 银行内部转账,从转出账号中扣除转账金额,给转入账号增加转账金额,需要保证以上两个操作 * 要么同时成功,要么同时失败 * fromAccountId 转出账号 * outAccountId 转入账号 * amount 转账金额 */ public void transferInner(String fromAccountId,String outAccountId,BigDecimal amount); /* * 外部转账-转出,从转出账号中扣除转账金额 * fromAccoutnId 转出账号 * amount 转账金额 */ public void transferOut(String fromAccountId,String outAccountId,BigDecimal amount); /* * 外部转账-转入,从转入账号中增加转账金额 * toAccoutnId 转出账号 * amount 转账金额 */ public void transerIn(String toAccountId,BigDecimal amount); }
我给你找找
package com.bj.calcultor;
import java.awt.Frame;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
import javax.swing.JButton;
import javax.swing.JPanel;
import javax.swing.JTextField;
public class Calcultor extends Frame implements ActionListener {
public static void main(String[] args) {//定义主方
new Calcultor();//创建匿名对象，并调用test()方法;
}
//定义按钮名称
String[] arr={"1","2","3","4","5","6","7","8","9","0","+","-","*","/","=","."};
JButton [] button=new JButton[arr.length];
JButton reset = new JButton("CE");
JTextField display = new JTextField(20);
//创建窗口，定义组件
//执行窗口事件:关闭窗口
private class WindowCloser extends WindowAdapter {
public void windowClosing(WindowEvent we) {
System.exit(0);
}
}
public Calcultor(){
super("计算器");//定义标题
//定义面板容器，并布局
JPanel jpanel=new JPanel(new GridLayout(4,4));
//添加按钮，并给按钮添加名称
for (int i = 0; i arr.length; i++) {
button[i]= new JButton(arr[i]);
jpanel.add(button[i]);
}
JPanel panel2 = new JPanel();
panel2.add("Northr", display);
display.setEnabled(false);
panel2.add("East", reset);
this.add("North", panel2);
this.add("Center", jpanel);
for (int i = 0; i arr.length; i++){
addWindowListener(new WindowCloser());
setVisible(true);
setSize(400,400);
pack();
button[i].addActionListener(this);
reset.addActionListener(this);
display.addActionListener(this);
}
}
@Override
public void actionPerformed(ActionEvent e) {//定义事件
// TODO Auto-generated method stub
Object target=e.getSource();
String lable=e.getActionCommand();
if(target==reset){
handleReset();
}else if("0123456789.".indexOf(lable)0){
handleNumber(lable);
}else{
hadleOperator(lable);
}
}
boolean isFirstDigit=true;
private void hadleOperator(String key) {
if(operator.equals("+")){
number += Double.valueOf(display.getText());
}else if (operator.equals("-")){
number -= Double.valueOf(display.getText());
}else if (operator.equals("*")){
number *= Double.valueOf(display.getText());
}else if (operator.equals("/")){
number /= Double.valueOf(display.getText());
}else if(operator.equals("=")){
number =Double.valueOf(display.getText());
}
display.setText(String.valueOf(number));
operator=key;
isFirstDigit=true;
}
private void handleNumber(String key) {
if(true){
display.setText(key);//把键值设置为文本框内容
}else if(key.equals(".") display.getText().indexOf(".")0){
display.setText(display.getText()+".");//把文本框内容设置：display.getText()+"."
}else if(!key.equals(".")){
display.setText(display.getText() + key);//把文本框内容设置：display.getText()+key
isFirstDigit=false;
}
}
private void handleReset() {
display.setText("0");
isFirstDigit=true;
operator="=";
}
String operator="=";
Double number=0.0;
}