java - 我的 Java 代码不断向文本文件添加重复项

Question

我正在用 Java 编写一些代码，这些代码将能够读取和写入股票投资组合项目的文本文件。我能够读取和写入，但是当我尝试在同一个运行程序类中读取文件两次时，它首先输出内容，然后输出两倍的内容，而不是输出相同的内容两次。

相关类(class)是(请原谅其长度):

import java.util.ArrayList;
import java.io.*;

public class FileModifier {
    private String path;
    private int numOfLines;
    private ArrayList<String[]> arr;
    private BufferedReader br;
    private BufferedWriter bw;

    public FileModifier(String p){
        path = p;
        numOfLines = 0;
        arr = new ArrayList<String[]>();
    }

    public void read(){
        try{
            br = new BufferedReader(new FileReader(path));
            String line;
            while ((line = br.readLine()) != null) {
                String[] row = line.split("\t\t");
                arr.add(row);
                numOfLines++;
            }
            br.close();
        }
        catch(Exception e){
        }
    }

    public void write(){
        try{
            read();
            bw = new BufferedWriter(new FileWriter(path));
            String content = "";
            for (String[] line : arr) {
                for (int i = 0; i < line.length; i++) {
                    content += (line[i] + "\t\t");
                }
                content += "\r";
            }
            bw.write(content);
            bw.close();
        }
        catch(Exception e){
        }
    }

    public ArrayList<String[]> getContents(){
        read();
        return arr;
    }

    public int getNumberOfLines(){
        read();
        return numOfLines;
    }

    public String[] getLine(int n){
        read();
        return arr.get(n);
    }

    public void addLine(int n, String[] newLine){
        read();
        arr.set(n, newLine);
    }
}

和

import java.util.ArrayList;

abstract public class Account {
    private FileModifier file;

    public Account(String historyPath){
        file = new FileModifier(historyPath);
    }

    abstract public double getBalance();

    public void addToHistory(String[] newLine){
        ArrayList<String[]> contents = file.getContents();
        contents.add(newLine);
        file.write();
    }

    public String getHistory(){
        String history = "";
        for(String[] line: file.getContents()){
            for(String part: line){
                history += part + "\t\t";
            }
            history += "\n";
        }
        return history;
    }
}

和

import java.util.ArrayList;
import java.util.Date;
import java.text.DecimalFormat;
import java.text.SimpleDateFormat;

public class StockAccount extends Account{
    private ArrayList<String[]> arr;
    private DecimalFormat df;
    private SimpleDateFormat da;
    private int numOfShares;
    private double portfolioValue;
    private double balance;
    private FileModifier portfolio;

    public StockAccount(String p){
        super("C:\\stock_transaction_history.txt");
        portfolio = new FileModifier(p);
        numOfShares = portfolio.getNumberOfLines();
        arr = portfolio.getContents();
        portfolioValue = 10000;
        balance = 10000;
        df = new DecimalFormat(".##");
        da = new SimpleDateFormat("HH:mm:ss");
    }

    public String displayPortfolio(){
        String output = "";
        String[] temp;
        for(int i = 0; i < numOfShares; i++){
            temp = arr.get(i);
            for(int k = 0; k < temp.length; k++){
                output += temp[k];
                output += "\t\t";
            }
            if(i < numOfShares - 1)
                output += "\r";
        }
        return output;
    }

    public double getStockPrice(String symbol){
        for(String[] line: arr){
            if(line[0].equals(symbol))
                return Double.parseDouble(line[2]);
        }
        return -1;
    }

    public int getAmountOwned(String symbol){
        for(String[] line: arr){
            if(line[0].equals(symbol))
                return Integer.parseInt(line[1]);
        }
        return -1;
    }

    public double getStockValue(String symbol){
        int amt = getAmountOwned(symbol);
        double price = getStockPrice(symbol);
        if(amt == -1 || price == -1){
            return -1;
        }
        return amt * price;
    }

    public double getBalance(){
        double value = 0;
        for(int i = 0; i < arr.size()/2; i++){
            value += getStockValue(arr.get(i)[0]);
        }
        balance = Double.parseDouble(df.format(portfolioValue - value));
        return balance;
    }

}

现在，当我尝试做

StockAccount sa = new StockAccount("C:\\Result.txt");
System.out.println(sa.getHistory());
System.out.println();
System.out.println(sa.getHistory());

我明白了

Event       Symbol      Owned       Price       Value       Time        
Buy     GOOG        10      $577.49     $5774.90        09:40:07        
Buy     MSFT        100     $30.00      $3000.00        13:37:00        


Event       Symbol      Owned       Price       Value       Time        
Buy     GOOG        10      $577.49     $5774.90        09:40:07        
Buy     MSFT        100     $30.00      $3000.00        13:37:00        
Event       Symbol      Owned       Price       Value       Time        
Buy     GOOG        10      $577.49     $5774.90        09:40:07        
Buy     MSFT        100     $30.00      $3000.00        13:37:00

我已经阅读了我的代码，但我没有看到文件会重复的任何地方。关于文件读取是否有一些我不知道的事情？

Answer 1

此时您应该使用调试器进入侦探模式。为什么它的第二次时间恰好是实际内容的两倍？内容存储在哪个变量中？什么时候追加的？你会不会无意中重复了两次？故意的吗？

仔细看看您是如何与 FileModifier#arr 交互的。