Ⅰ java 如何对读入的txt文件进行修改啊。。。
这个是一行行读的吧，读到第一行的时候按位置修改分数，然后再输出一个txt覆盖掉原来的
Ⅱ 用JAVA实现对txt文件文本增删改查
正好今天写了个~原来是两个类，好吧，加一个…= =~囧以文件的形式存储的import java.io.File;import java.io.FileInputStream;import java.io.FileOutputStream;import java.io.ObjectInputStream;import java.io.ObjectOutputStream;import java.io.Serializable;import java.util.Arrays;import java.util.HashMap;import java.util.HashSet;import java.util.Scanner;import java.util.Set;public class StudentManager {private static File DB = new File("students.db");private static Set<Student> studentList = null;@SuppressWarnings("unchecked")private static void initStudentList() {if (DB.exists()) {FileInputStream fi = null;ObjectInputStream oi = null;try {fi = new FileInputStream(DB);oi = new ObjectInputStream(fi);Object obj = oi.readObject();fi.close();oi.close();if (obj instanceof Set)studentList = (Set<Student>) obj;} catch (Exception e) {e.printStackTrace();}}if (studentList == null)studentList = new HashSet<Student>();}private static void save() {if (studentList == null)return;if (!DB.exists())try {DB.createNewFile();} catch (Exception e) {e.printStackTrace();}FileOutputStream fo;try {fo = new FileOutputStream(DB);ObjectOutputStream oo = new ObjectOutputStream(fo);oo.writeObject(studentList);fo.close();oo.close();} catch (Exception e) {e.printStackTrace();}}private static Student[] getStudents(int id, String name) {HashSet<Student> rlt = new HashSet<Student>();if (id != 0) {for (Student s : studentList) {if (s.id == id)rlt.add(s);}} else if (name != null && !name.isEmpty()) {for (Student s : studentList) {if (s._name.equalsIgnoreCase(name))rlt.add(s);}}return rlt.toArray(new Student[0]);}static {initStudentList();}static void out(Object obj){System.out.println(obj);}public static void menu() {out("Welcome to use Student Manager!\n1-search student;\t2-add student;\t3-list all students;\nothers-exit");Scanner in = new Scanner(System.in);Student student = null;String input = in.nextLine();if (input.equals("1")) {Student[] students = new Student[0];out("please input name/id");String ins = in.nextLine();if (ins.matches("\\d+"))students = getStudents(Integer.parseInt(ins), null);elsestudents = getStudents(0, ins);if (students.length != 0) {out(Arrays.toString(students).replaceAll("\\[|\\]|, ", "\n"));if (students.length == 1)student = students[0];else {out("please choose a student by id:\n");int i = in.nextInt();for (Student s : students) {if (s.id == i) {student = s;break;} else {out("error");menu();}}}out("1-set score;\t2-delete score;\t3-delete student;\tother-exit");int input1=in.nextInt();in.nextLine();String course=null;float score=0;switch(input1){case 1:out("please input course");course=in.nextLine();out("please input score");score = in.nextFloat();in.nextLine();student.setScore(course, score);break;case 2:out("please input course");course=in.nextLine();student.removeScore(course);break;case 3:student.removeFrom(studentList);break;}}else {out("NO current record!");}}if (input.equals("2")) {out("please input id");int id=in.nextInt();in.nextLine();out("please input name");String name = in.nextLine();out("please input class");String cname=in.nextLine();student=new Student(id, name, cname);if(studentList.add(student)){ out("create success!\n"); String input2="-"; while(!input2.isEmpty()){ out("set score? \n1-yes;\t2-no"); input2=in.nextLine(); if(input2.equals("1")){ out("please input course");String course=in.nextLine();out("please input score");float score = in.nextFloat();student.setScore(course, score);in.nextLine();} else break; }}else out("Error: id or student exists");}if (input.equals("3")) {out(studentList.toString().replaceAll("\\[|\\]|, ", "\n"));}if(input.isEmpty())return;save();menu();}public static void main(String[] args){menu();}}class Student implements Serializable {public String toString() {return "id: " + id + "\tclass: " + _class + "\tname: " + _name+ courses.toString().replaceAll("\\{|\\}|, ", "\n").replaceAll("=", ": ");}Student(int id, String _name, String _class) {this.id = id;this._class = _class;this._name = _name;}private static final long serialVersionUID = 1L;public int id = 0;public String _name = "";public String _class = "";HashMap<String, Float> courses = new HashMap<String, Float>();void setScore(String course, float score) {courses.put(course, score);System.out.println("set success!\n\n"+this);}void removeScore(String course) {courses.remove(course);System.out.println("delete success!\n\n"+this);};void removeFrom(Set<?> list) {list.remove(this);System.out.println("delete success!");}public int hashCode() {return 31;}public boolean equals(Object obj) {Student s = null;if(obj instanceof Student){System.out.println(1);s=(Student)obj;return s.id==id||(s._class.equals(_class)&&s._name.equals(_name));}return false;}}class DaJiangYou{DaJiangYou(){System.out.println("I am da jiang you");}}
Ⅲ java文件流txt文档内容增删改
import java.io.BufferedReader;import java.io.FileInputStream;import java.io.FileNotFoundException;import java.io.FileOutputStream;import java.io.IOException;import java.io.InputStreamReader;import java.io.OutputStreamWriter;import java.io.PrintWriter;import java.util.ArrayList;import java.util.List;public class UpdateTxt {static List<String> txt = new ArrayList<String>();public static void main(String[] args) {read("D:/lj/12.txt");//add(2,"asd");delete(2);//addToFinal("asd");write("D:/lj/12.txt");}//读取public static void read(String path){String temp = null;int i = 0;try {BufferedReader br = new BufferedReader(new InputStreamReader(new FileInputStream(path)));while((temp = br.readLine()) != null){txt.add(temp);}} catch (FileNotFoundException e) {// TODO Auto-generated catch blocke.printStackTrace();} catch (IOException e) {// TODO Auto-generated catch blocke.printStackTrace();}}//写回public static void write(String path){try {PrintWriter pw = new PrintWriter(new OutputStreamWriter(new FileOutputStream(path)));for(int i = 0; i<txt.size() ; i++){pw.println(txt.get(i));pw.flush();}} catch (FileNotFoundException e) {// TODO Auto-generated catch blocke.printStackTrace();}}//添加到第几行public static void add(int line , String s){txt.add(line-1, s);}//删除某行public static void delete(int line){txt.remove(line – 1);}//添加到最后public static void addToFinal(String s){txt.add(s);}}
Ⅳ java io流对文件的增删改查
可以通过BufferedReader 流的形式进行流读取，之后通过readLine方法获取到的内容,之后通过if判断来实现在某些特定位置的查找、增加、删除、修改操作。举例：BufferedReader bre = null;OutputStreamWriter pw = null;//定义一个流try {String file = "D:/test/test.txt";bre = new BufferedReader(new FileReader(file));//此时获取到的bre就是整个文件的缓存流pw = new OutputStreamWriter(new FileOutputStream(“D:/test.txt”),"GBK");//确认流的输出文件和编码格式，此过程创建了“test.txt”实例while ((str = bre.readLine())!= null) // 判断最后一行不存在，为空结束循环{if(str.indexOf("排除")<0){//判断是否需要舍弃pw.write(str);//将要写入文件的内容，可以多次write}}bre.close();//关闭流pw.close();//关闭流解释：以上方法是实现的删除，if中的条件改变下，即可实现其余的功能。备注：文件流用完之后必须及时通过close方法关闭，否则会一直处于打开状态，直至程序停止，增加系统负担。
Ⅳ 如何通过java实现对指定目录下的txt文件进行增删改查
代码如下：
importjava.io.BufferedReader;importjava.io.BufferedWriter;importjava.io.FileInputStream;importjava.io.FileOutputStream;importjava.io.IOException;importjava.io.InputStreamReader;importjava.io.OutputStreamWriter;importjava.util.ArrayList;importjava.util.List;publicclassApp61{publicstaticvoidmain(String[]args)throwsIOException{//查找行输出Stringline=findFileLine("mylist.txt","abc");System.out.println(line);//删除指定行removeFileLine("mylist.txt",2);}staticvoidremoveFileLine(Stringfile,intline)throwsIOException{List<String>lines=readFileLines(file);lines.remove(line-1);FileOutputStreamoutputStream=null;=null;BufferedWriterwriter=null;try{outputStream=newFileOutputStream(file);streamWriter=newOutputStreamWriter(outputStream);writer=newBufferedWriter(streamWriter);for(Stringstr:lines){writer.write(str+System.lineSeparator());}}finally{if(writer!=null){writer.close();}if(streamWriter!=null){streamWriter.close();}if(outputStream!=null){outputStream.close();}}}//查找行staticStringfindFileLine(Stringfile,Stringkeywork)throwsIOException{List<String>lines=readFileLines(file);for(Stringline:lines){if(line.contains(keywork)){returnline;}}return"";}//返回文件所有行staticList<String>readFileLines(Stringfile)throwsIOException{List<String>lines=newArrayList<>();FileInputStreaminputStream=null;InputStreamReaderstreamReader=null;BufferedReaderreader=null;try{inputStream=newFileInputStream(file);streamReader=newInputStreamReader(inputStream);reader=newBufferedReader(streamReader);Stringline="";while((line=reader.readLine())!=null){lines.add(line);}}finally{if(reader!=null){reader.close();}if(streamReader!=null){streamReader.close();}if(inputStream!=null){inputStream.close();}}returnlines;}}
Ⅵ Java实现对txt的增删改查中，怎么把txt中重名的几条信息都删了。比如txt中有好多人的信息，
使用java读取txt文件,使用List集合
判断List集合中重复信息,如果重复,删除
请采纳 谢谢
publicstaticvoidmain(String[]args){List<String>values=newArrayList<String>();Map<String,Boolean>map=newHashMap<String,Boolean>();try{BufferedReaderbf=newBufferedReader(newInputStreamReader(newFileInputStream("d:/d.txt")));Stringvalue="";while((value=bf.readLine())!=null){value=value.trim();if(!value.equals("")){if(map.get(value)==null){values.add(value);map.put(value,true);}}}for(Stringstring:values){System.out.println(string);}}catch(FileNotFoundExceptione){//TODOAuto-generatedcatchblocke.printStackTrace();}catch(IOExceptione){//TODOAuto-generatedcatchblocke.printStackTrace();}}
Ⅶ 用java在txt文件下对文件进行增删改查，是否需要用流先给txt文件读入
一般来说，只要不是对文件进行读写，是不需要流的。但涉及到文件内容的读和写，肯定需要流
Ⅷ 用java读写txt格式文件里的数据，并实现对数据的增删改查，求大神知道一二，小弟刚涉足，不是太懂。，
实体类：AAA属性 id,testDate,road,num1,type1,num2,type2 记得添加get，set方法.每读取一行时值添加到AAA实体类对应属性中，然后add至List。楼主用好StringTokenizer 不建议用了，用string.split()方法吧 。循环：AAA bean = null;List<AAA> list = new ArrayList<AAA>();while (…) {bean = new AAA(); String[] arr = s.split("空格数自定"); String id = arr[0].trim();String testDate= arr[1].trim();//考虑是否转为时间格式//依次读取//将读取的值录入到bean中bean.setId(id);bean.setTestDate(testDate);//…依次录入list.add(bean);//将值添加到集合中} //OK ，真累！
Ⅸ 用java在图形用户界面下的txt文件下对文件进行增删改查
就写个新增的吧。其他你照着写。package com.zz.jfram;import java.awt.BorderLayout;import java.awt.FlowLayout;import java.awt.event.ActionEvent;import java.awt.event.ActionListener;import java.io.File;import java.io.IOException;import javax.swing.JButton;import javax.swing.JFileChooser;import javax.swing.JFrame;import javax.swing.JLabel;import javax.swing.JPanel;import javax.swing.JTextArea;import javax.swing.JTextField;public class TxtManage extends JFrame {private static final long serialVersionUID = 1L;public TxtManage() {final JFrame jFrame = new JFrame();JButton jButton = new JButton("新增");JPanel jPanel = new JPanel();final JTextField jTextField = new JTextField(30);final JLabel jLabel = new JLabel("请输入新增文件的名字:");jPanel.add(jLabel, FlowLayout.LEFT);jPanel.add(jTextField, FlowLayout.CENTER);jPanel.add(jButton, FlowLayout.RIGHT);jFrame.add(jPanel, BorderLayout.NORTH);// 设置窗体属性jFrame.setBounds(500, 50, 600, 400);final JTextArea jTextArea = new JTextArea(50, 50);// 新增按钮点击事件jButton.addActionListener(new ActionListener() {@Overridepublic void actionPerformed(ActionEvent e) {JFileChooser jfc = new JFileChooser();jfc.setDialogTitle("选择路径");jfc.setFileSelectionMode(JFileChooser.DIRECTORIES_ONLY);// 只能选择目录if (jfc.showOpenDialog(jFrame) == JFileChooser.APPROVE_OPTION) {// 选中目录的绝对路径String path = jfc.getSelectedFile().getAbsolutePath();// 在当前目录新增一个文件File file = new File(path+"\\"+jTextField.getText()+".txt");if (!file.exists()) {try {file.createNewFile();jTextArea.setText("文件新增成功！");} catch (IOException e1) {e1.printStackTrace();}}else{ try {throw new Exception("文件已存在!");} catch (Exception e1) {e1.printStackTrace();}}}}});jFrame.add(jTextArea, BorderLayout.CENTER);jFrame.setVisible(true);// 关闭处理动作jFrame.setDefaultCloseOperation(EXIT_ON_CLOSE);}public static void main(String[] args) {new TxtManage();}}
Ⅹ 用Java写一个基于txt文本的控制台输入的增删查改
packagecom.list;/**Author:qcq*Date:2015/7/20*E-mail:[email protected]**/importjava.io.BufferedReader;importjava.io.File;importjava.io.FileReader;importjava.io.FileWriter;importjava.io.IOException;importjava.util.HashMap;importjava.util.Map;importjava.util.Scanner;importjava.util.Set;publicclassQuery{classPerson{publicStringId;/*shouldbesurethisisunique*/publicStringname;publicintage;publicbooleansex;/*trueforman,falseforgirl*/@OverridepublicStringtoString(){returnId+""+name+""+age+""+(sex?"M":"F");}}privateMap<String,Person>people;privateStringfileName;publicQuery(StringfileName){people=newHashMap<String,Person>();this.fileName=fileName;if(!initial()){System.out.println(""+"storefilepath,pleasecheckit,andrerunthisprogram.");}}privatebooleaninitial(){booleanflag=false;try{Filefile=newFile(fileName);if(!file.exists()){System.out.println("Thefilenotexist,wewillcreateitforyou");file.createNewFile();}BufferedReaderreader=newBufferedReader(newFileReader(fileName));Stringline=reader.readLine();while(null!=line&&!line.equals("")){String[]splitLine=line.split("+");if(splitLine.length<4){System.out.println("Theinformationnotenough");returnflag;}Persontemp=newPerson();temp.Id=splitLine[0];temp.name=splitLine[1];temp.age=Integer.valueOf(splitLine[2]);temp.sex=splitLine[3].equals("M")?true:false;people.put(temp.Id,temp);line=reader.readLine();}flag=true;}catch(IOExceptione){e.printStackTrace();}returnflag;}publicbooleanwriteInFile(){booleanflag=false;try{FileWriterwriter=newFileWriter(fileName);Set<String>key=people.keySet();for(StringkeyIndex:key){writer.write(people.get(keyIndex).toString()+"");}}catch(IOExceptione){e.printStackTrace();}returnflag;}/**/publicbooleanadd(){returnfalse;}publicbooleandelete(){returnfalse;}publicbooleanquery(){returnfalse;}publicbooleanupdate(){returnfalse;}publicstaticvoidmain(String[]args){Querydata=newQuery("temp.txt");/*hereshoulddefinethefilename*/Scannerin=newScanner(System.in);System.out.println("Hereyoucanchoicewhichoption:"+"quit:forquit"+"a:foradd"+"d:fordelete"+"u:forupdate"+"q:forquery");Stringoption=in.next();label:while(null!=option&&!option.equals("")){switch(option){case"quit":breaklabel;case"a":/*hereaddthefunction*/data.add();break;case"d":/*hereaddthefunction*/data.delete();break;case"u":/*hereaddthefunction*/data.update();break;case"q":/*hereaddthefunction*/data.query();break;default:breaklabel;}}if(null!=in){in.close();}}}
