对于我的班级，我们必须将股票信息放入数组的元素中，并显示每个股票及其符号的变化百分比。我有它工作的地方，它将打印第一个对象五次与五个对象一次就像它想象的那样。
这是我的代码（说明在评论中）：
import java.util.Scanner;
public class StockTest{
public static void main(String[] args){
Scanner input = new Scanner(System.in);
/*
Make sureto complete the Stock class before you do the following items.
*/
/* Step 1:
* Instantiate two Stock objects with arguments of your choice(stock symbol and name).
* Using two set methods set the previousClosingPrice and curentPrice of two Stocks.
* Display the percentage changed from previousClosingPrice to curentPrice of both stocks.
*/
System.out.println("Input stock symbol");
String symbol = input.next();
System.out.println("Input stock name");
String name = input.next();
Stock stock = new Stock(symbol, name);
System.out.println("Input previous price");
Stock.setPreviousClosingPrice(input.nextDouble());
System.out.println("Input current price");
Stock.setCurrentPrice(input.nextDouble());
System.out.println("the change percentage of the stock is " + Stock.getChangePercent() + "%");
/*
* Step 2: Declare an array of 5 Stock objects. (Next three steps should be done in a loop)
* Ask the user to input stock symbol, name, previousClosingPrice and curentPrice.
* Initialize an array element with new Stock object using symbol and name that user input.
* Using two set methods set the previousClosingPrice and curentPrice of each Stock element
*/
Stock[] stockArray = new Stock[5];
for(int i = 0; i < stockArray.length; i++){
System.out.println("Please input stock symbol, name, previous price, and current price");
String stockSymbol = input.next();
String stockName = input.next();
stockArray[i] = new Stock(symbol, name);
Stock.setPreviousClosingPrice(input.nextDouble());
Stock.setCurrentPrice(input.nextDouble());
}
/*
* Step 4: (this step should be done in a loop)
* Display the percentage changed from previousClosingPrice to curentPrice of all stocks with their symbol.
*/
for (int i = 0; i < stockArray.length; i++){
System.out.println("Percentage changed of " + symbol + " " + Stock.getChangePercent());
}
} }
答案 0 :(得分：2)
您正在使用错误的变量来初始化Stock实例。
更改
String stockSymbol = input.next();
String stockName = input.next();
stockArray[i] = new Stock(symbol,name);
到
String stockSymbol = input.next();
String stockName = input.next();
stockArray[i] = new Stock(stockSymbol,stockName);
目前尚不清楚您创建的第一个Stock实例的目的是什么（Stock stock = new Stock(symbol, name);），因为在初始化之后您没有对它执行任何操作。
答案 1 :(得分：0)
我的代码可能会遇到一些问题：
如下所示，直接在数组中创建和存储Stock对象会产生开销，因为您还需要更新同一对象的剩余属性。
stockArray[i] = new Stock(symbol, name);
使用静态方法更新对象属性没有意义。
Stock.setPreviousClosingPrice(input.nextDouble());
Stock.setCurrentPrice(input.nextDouble());
需要仔细使用扫描仪方法。
我尝试按照评论更正代码：
StockTest课程：
import java.util.Scanner;
public class StockTest {
public static void main(String[] args) {
Scanner input = new Scanner(System.in);
/*
* Make sureto complete the Stock class before you do the following
* items.
*/
/*
* Step 1: Instantiate two Stock objects with arguments of your
* choice(stock symbol and name). Using two set methods set the
* previousClosingPrice and curentPrice of two Stocks. Display the
* percentage changed from previousClosingPrice to curentPrice of both
* stocks.
*/
System.out.println("Input stock symbol");
String symbol = input.nextLine();
System.out.println("Input stock name");
String name = input.nextLine();
Stock stock1 = new Stock(symbol, name);
System.out.println("Input previous price");
stock1.setPreviousClosingPrice(Double.parseDouble(input.nextLine()));
System.out.println("Input current price");
stock1.setCurrentPrice(Double.parseDouble(input.nextLine()));
System.out.println("Input stock symbol");
symbol = input.nextLine();
System.out.println("Input stock name");
name = input.nextLine();
Stock stock2 = new Stock(symbol, name);
System.out.println("Input previous price");
stock2.setPreviousClosingPrice(Double.parseDouble(input.nextLine()));
System.out.println("Input current price");
stock2.setCurrentPrice(Double.parseDouble(input.nextLine()));
System.out.println("the change percentage of the stock is "
+ stock1.getChangePercent() + "%");
System.out.println("the change percentage of the stock is "
+ stock2.getChangePercent() + "%");
/*
* Step 2: Declare an array of 5 Stock objects. (Next three steps should
* be done in a loop) Ask the user to input stock symbol, name,
* previousClosingPrice and curentPrice. Initialize an array element
* with new Stock object using symbol and name that user input. Using
* two set methods set the previousClosingPrice and curentPrice of each
* Stock element
*/
Stock[] stockArray = new Stock[2];
for (int i = 0; i < stockArray.length; i++) {
System.out
.println("Please input stock symbol, name, previous price, and current price");
symbol = input.nextLine();
name = input.nextLine();
Stock stock = new Stock(symbol, name);
stock.setPreviousClosingPrice(Double.parseDouble(input.nextLine()));
stock.setCurrentPrice(Double.parseDouble(input.nextLine()));
stockArray[i] = stock;
}
/*
* Step 4: (this step should be done in a loop) Display the percentage
* changed from previousClosingPrice to curentPrice of all stocks with
* their symbol.
*/
for (Stock stock : stockArray) {
System.out.println("Percentage changed of " + stock.getSymbol()
+ " " + stock.getChangePercent() + "%");
}
}
}
库存类
public class Stock {
private String name;
private String symbol;
private double previousClosingPrice;
private double currentPrice;
public Stock(String symbol, String name) {
this.symbol = symbol;
this.name = name;
}
public String getName() {
return this.name;
}
public String getSymbol() {
return this.symbol;
}
public void setCurrentPrice(double currentPrice) {
this.currentPrice = currentPrice;
}
public void setPreviousClosingPrice(double previousClosingPrice) {
this.previousClosingPrice = previousClosingPrice;
}
public double getChangePercent() {
return (this.currentPrice / this.previousClosingPrice - 1) * 100;
}
}