Question

我是一个完整的java新手。如果你能帮助我，那就太好了。所以我需要写一个程序，赚钱交易。我写它的方式如下：

class program
{

    public static void main (String[] param)throws IOException
    {
        intro();
        System.exit(0);
    }
    public static void intro()throws IOException
    {
        PrintWriter x =new PrintWriter(new FileWriter("data.txt"));
        while (true)
        {
            Object[] possibleValues = { "Transfer", "Receive", "Cancel"};
            Object selectedValue = JOptionPane.showInputDialog(null,"Choose one", "Input",JOptionPane.INFORMATION_MESSAGE, null, possibleValues, possibleValues[0]);

            String name;
            String surname;
            String amount;
            String info;

            if(selectedValue.equals(possibleValues[0]))
            {
                name = JOptionPane.showInputDialog(null, "recipients name");
                surname = JOptionPane.showInputDialog(null, "recipients surname");
                amount = JOptionPane.showInputDialog(null, "amount");
                info = name+surname+amount;
                x.println(info);



            }

            else if(selectedValue.equals(possibleValues[1]))
            {
                String inputname;
                String inputsurname;
                String inputamount;
                inputname = JOptionPane.showInputDialog(null, "your name");
                inputsurname = JOptionPane.showInputDialog(null, "your surname");
                inputamount = JOptionPane.showInputDialog(null, "amount");
                String inputinfo = inputname + inputsurname + inputamount;

                if(x.contains.String(inputinfo))
                {
                    JOptionPane.showMessageDialog(null,"you will recieve "+inputamount+"$");
                }
                else
                {
                    JOptionPane.showMessageDialog(null,"request not found");
                }

            }
            else if(selectedValue.equals(possibleValues[2]))
            {
                x.close();
                System.exit(0);
            }
        }

    }
}

除了：

之外，一切似乎都在起作用

If (x.contains.String(inputinfo))行

这个程序应该做的基本上是，当你进行交易时，它会删除你想要给他们的姓氏和金额的人，并将其存储在data.txt中，当这个人想要收钱时写下来记下他应该收到的姓名和金额，如果该信息与data.txt中存储的信息相符，程序会告诉他们他们会收到金额，但如果不匹配则程序会告诉他们该请求尚未找到。

程序中存储名称和数量的部分在data.txt中有效;只有发现它的部分不会。请帮忙。

Answer 1

正如Java doc所说，PrintWriter用于写入文件。在您的情况下，我建议您使用BufferedReader课程。您可以使用其readLine方法逐行读取并搜索文本。

大致如此......

BufferedReader br = new BufferedReader(new FileReader(new File("data.txt")));
while((line = br.readLine()) != null)
{
     if (line.contains("your text")
         //do
}

Answer 2

没有时间为您优化代码;但以下情况可行：

package Rezi30035097;

import java.io.BufferedReader;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.io.PrintWriter;
import javax.swing.JOptionPane;


class Program01 {

    protected static BufferedReader br;
    protected static PrintWriter x;

    public static void main(String[] param) throws IOException {
        intro();
        System.exit(0);
    }

    protected static boolean matchString(String s) throws FileNotFoundException, IOException {
        br = new BufferedReader(new FileReader(new File("data.txt")));
        String line;
        while ((line = br.readLine()) != null) {
            if (line.contains(s)) {

                br.close();
                br = null;
                return true;
            }
        }
        return false;
    }

    public static void intro() throws IOException {
        x = new PrintWriter(new FileWriter("data.txt"));

        while (true) {
            Object[] possibleValues = {"Transfer", "Receive", "Cancel"};
            Object selectedValue = JOptionPane.showInputDialog(null, "Choose one", "Input", JOptionPane.INFORMATION_MESSAGE, null, possibleValues, possibleValues[0]);

            String name;
            String surname;
            String amount;
            String info;

            if (selectedValue.equals(possibleValues[0])) {
                name = JOptionPane.showInputDialog(null, "recipients name");
                surname = JOptionPane.showInputDialog(null, "recipients surname");
                amount = JOptionPane.showInputDialog(null, "amount");
                info = name + surname + amount;

                x.write(info);
                x.flush();

            } else if (selectedValue.equals(possibleValues[1])) {
                String inputname;
                String inputsurname;
                String inputamount;
                inputname = JOptionPane.showInputDialog(null, "your name");
                inputsurname = JOptionPane.showInputDialog(null, "your surname");
                inputamount = JOptionPane.showInputDialog(null, "amount");
                String inputinfo = inputname + inputsurname + inputamount;

                if (matchString(inputinfo)) {
                    JOptionPane.showMessageDialog(null, "You will receive " + inputamount + "$");
                } else {
                    JOptionPane.showMessageDialog(null, "Request not found");
                }
                inputinfo = null;

            } else if (selectedValue.equals(possibleValues[2])) {
                x.close();
                System.exit(0);
            }
        }

    }
}

在文本文件中查找字符串

2 个答案: