Question

我需要编写一个Java程序，将控制台中输入的信息写入.txt文件。如果.txt文件已经存在，则必须打开它并在另一行上写入附加信息。如果新的“Lifter”不存在.txt文件，它将创建.txt并将其写入。基本上我不知道如何为输入的每个名称创建新的.txt以及如何编辑它person的.txt已经存在。我该怎么做呢？

import java.io.IOException;
import java.io.PrintWriter;
import java.util.Random;
import java.util.Scanner;

public class MeetPrinter {

    public static void getInfo() {

        Scanner scanner = new Scanner(System.in);
        int question;
        String firstName;
        String lastName;
        int squat;
        int bench;
        int lift;
        String meetName;
        do {

            System.out.println("Enter first name: ");
            firstName = scanner.next();

            System.out.println("Enter Last Name: ");
            lastName = scanner.next();

            System.out.println("Enter new Meet Name: ");
            meetName = scanner.next();

            System.out.println("Enter max squat weight in kg: ");
            squat = scanner.nextInt();

            System.out.println("Enter max bench press in kg: ");
            bench = scanner.nextInt();

            System.out.println("Enter max deadlift in kg: ");
            lift = scanner.nextInt();

            System.out
                    .println("Enter '1' to enter more lifters or '2' if you are done entering.");
            question = scanner.nextInt();
        } while (question == 1);

        try{
            PrintWriter out = new PrintWriter("output.txt");
            Random randomGenerator = new Random();
            int randomInt = randomGenerator.nextInt(100000);
            out.println(lastName + ", " + firstName + " Record #: " + randomInt);
            out.println("");
            String meet = "Meet Name";
            String sq = "SQ Max";
            String bp = "BP Max";
            String sub = "SUB Total";
            String dl = "DL Max";
            String tot = "Total";
            out.printf("%20s %15s %18s %19s %18s %18s",meet ,sq,bp,sub,dl,tot);
            out.println("");
            out.printf("%20s", meetName);
            out.printf("%10d (%6.2f)", squat, squat * 2.2);
            out.printf("%10d (%6.2f)", bench, bench * 2.2);
            float subPounds = (float) ((float)(squat + bench) * 2.2);
            out.printf("%10d (%6.2f)", squat + bench, subPounds);
            out.printf("%10d (%6.2f)", lift, lift * 2.2);
            float tPounds = (float) ((float)(squat + bench + lift) * 2.2);
            out.printf("%10d (%6.2f)", squat + bench + lift, tPounds);
            out.close();
        }catch(IOException e){
            e.printStackTrace();
        }
    }

}

Answer 1

<强>更新

变化

PrintWriter out = new PrintWriter("output.txt");

到

FileWriter out = new FileWriter("output.txt", true);

如果文件存在，true将告诉FileWriter附加到文件，这正是您想要做的。

这是FileWriter的javadoc。

FileWriter可以选择编写字符串，这就是你所做的。

也像twain249建议的那样，对路径做点什么......

Answer 2

Java文件操作

File file  = new File("<file name>");
BufferedWriter writer = null;

if(file.exists()){ //Check existence check 
writer = new BufferedWriter(new FileWriter(toFile,true)); 
//bytes will be written to the end of the file rather than the beginning
}else{
file.createNewFile() //creating new file
writer = new BufferedWriter(new FileWriter(toFile)); 
}
BufferedWriter writer = new BufferedWriter(writer);
writer.write(...);
---or----
PrintWriter out
   = new PrintWriter(new BufferedWriter(writer));
out.println(...);

Answer 3

您应该使用FileWriter。 API：http://docs.oracle.com/javase/1.4.2/docs/api/java/io/FileWriter.html 示例：http://www.roseindia.net/java/beginners/java-write-to-file.shtml

有条件的例子：google'写入文件java示例'

编辑.text文件Java

3 个答案: