小编use*_*477的帖子

我有一个程序,可以将人员添加到arraylist.我想要做的是将这些人添加到文本文件中,但程序会覆盖第一行,以便人员被删除.

如何告诉编译器在下一个空闲行写入？

import java.io.*;
import java.util.*;
import javax.swing.JTextArea;

public class Logic {

File file;
FileWriter fw;
FileReader fr;
BufferedWriter bw;
ArrayList<Person> person;

public Logic() {
    try {
        file = new File("register.txt");

        if (!file.exists()) {
            file.createNewFile();
        }
    } catch (IOException e) {
    }

    person = new ArrayList<Person>();
}

// Add person
public void addPerson(String name, int tele) {
    person.add(new Person(name, tele));
    savePerson(name, tele);
}

// Save person to external file
public void savePerson(String name, int tele) {
    try {
        fw = …

我正在尝试用字符串写一个文件,然后阅读它.但是,当我看到它看起来很奇怪与正方形和东西..我无法复制粘贴!

这是代码:

import java.io.*;

public class ObjectOutputStreamDemo {
public static void main(String[] args) throws ClassNotFoundException {
    try {
        //Now Im writing
        ObjectOutputStream output = new ObjectOutputStream(new FileOutputStream("fruit.dat"));

        String ord[] = { "Banana", "Mango", "Apple", "Passionfruit","Orange" };

        for (int i = 0; i < 5; i++) {
            output.writeObject(ord[i]);
        }
        output.close();

        //Now Im trying to read.
        BufferedReader in = new BufferedReader(new FileReader("fruit.dat"));
        String str;
        while ((str = in.readLine()) != null) {
            System.out.println(str);
        }

    } catch (IOException e) {
        System.out.println("Problem with file.");
    } …