Question

我需要建立一个系统，用于将客户信息和所有报价存储到外部文件，以及输入更多客户，列出客户，以及相同的报价。除此之外，我需要将所有报价/客户链接到ID。我基本上需要在java中做SQL。但是，我真的需要帮助我的输入和输出系统，并将所有信息写入数组。我有两个主要的代码，但它们效率很低，我需要一些建议，改进或完全不同的系统。从文件代码输入：

import java.io.*; //import classes
import java.util.ArrayList; 
import java.util.Iterator;
public class MyTextReader{
   public static void main(String[] args){
    String myDirectory = System.getProperty("user.dir");
    String fullDirectory = myDirectory + "\\myText.txt";
    String input_line = null;
       ArrayList<String> textItems = new ArrayList<String>(); //create array         list
    try{
        BufferedReader re = new BufferedReader(new FileReader(fullDirectory));
        while((input_line = re.readLine()) != null){
            textItems.add(input_line); //add item to array list
        }
    }catch(Exception ex){
           System.out.println("Error: " + ex);
    }
       Iterator myIteration = textItems.iterator(); //use Iterator to cycle list
       while(myIteration.hasNext()){ //while items exist
         System.out.println(myIteration.next()); //print item to command-line
       }
   }    
}

输出到文件

import java.io.FileWriter; //import classes
import java.io.PrintWriter;
public class MyTextWriter{
    public static void main(String[] args){
        FileWriter writeObj; //declare variables (uninstantiated)
        PrintWriter printObj;
             String myText = "Hello Text file"; 
        try{ //risky behaviour – catch any errors
                writeObj = new FileWriter("C:\\Documents\\myText.txt" , true);
           printObj = new PrintWriter(writeObj);//create both objects
           printObj.println(myText);  //print to file
           printObj.close(); //close stream
          }catch(Exception ex){
       System.out.println("Error: " + ex);
          }     
    }   
}

Answer 1

用于从文件中读取文本

    FileReader fr = new FileReader("YourFile.txt");
            BufferedReader br = new BufferedReader(fr);
            String s="";
            s=br.readLine();
System.out.println(s);

将文字写入文件

PrintWriter writeText = new PrintWriter("YourFile.txt", "UTF-8");
        writeText.println("The first line");
        writeText.println("The second line");
        writeText.close();

从文本文件读取/写入变量到变量

1 个答案: