用java写一个可以实现文本文件的读入、复制、查询和修改的程序，写出全带啊

### 回答1：
好的。下面是一个可以实现文本文件的读入、复制、查询和修改的 Java 程序：

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.util.Scanner;

public class TextFileOperations {
  public static void main(String[] args) {
    // 读入文件
    File file = new File("file.txt");
    try (BufferedReader reader = new BufferedReader(new FileReader(file))) {
      String line;
      while ((line = reader.readLine()) != null) {
        System.out.println(line);
      }
    } catch (IOException e) {
      e.printStackTrace();
    }
    
    // 复制文件
    File copyFile = new File("copy_file.txt");
    try (BufferedReader reader = new BufferedReader(new FileReader(file));
         BufferedWriter writer = new BufferedWriter(new FileWriter(copyFile))) {
      String line;
      while ((line = reader.readLine()) != null) {
        writer.write(line);
        writer.newLine();
      }
    } catch (IOException e) {
      e.printStackTrace();
    }
    
    // 查询文件
    Scanner scanner = new Scanner(System.in);
    System.out.print("请输入要查询的字符串：");
    String query = scanner.nextLine();
    try (BufferedReader reader = new BufferedReader(new FileReader(file))) {
      String line;
      int lineNum = 0;
      while ((line = reader.readLine()) != null) {
        lineNum++;
        if (line.contains(query)) {
          System.out.println("在第 " + lineNum + " 行找到了查询的字符串：" + line);
        }
      }
    } catch (IOException e) {
      e.printStackTrace();
    }
    
    // 修改文件
    System.out.print("请输入要修改的字符串：");
    String oldStr = scanner.nextLine();
    System.out.print("请输入修改后的字符串：");
    String newStr = scanner.nextLine();
    try (BufferedReader reader = new BufferedReader(new FileReader(file));
         BufferedWriter writer = new BufferedWriter(new FileWriter(copyFile))) {
      String line;
      while ((line = reader.readLine()) != null) {
        if (line.cont  

### 回答2：
下面是一个可以实现文本文件的读入、复制、查询和修改的Java程序的示例：

import java.io.*;

public class FileOperations {
public static void main(String[] args) {
// 读取文本文件
String content = readFile("input.txt");
System.out.println("读取的内容是：\n" + content);

// 复制文本文件
boolean copied = copyFile("input.txt", "copy.txt");
System.out.println("复制文件是否成功：" + copied);

// 查询文本文件
boolean found = searchFile("input.txt", "hello");
System.out.println("文件中是否包含关键词\"hello\"：" + found);

// 修改文本文件
boolean modified = modifyFile("input.txt", "hello", "world");
System.out.println("文件是否成功修改：" + modified);
}

// 读取文本文件
public static String readFile(String filename) {
StringBuilder content = new StringBuilder();
try (BufferedReader reader = new BufferedReader(new FileReader(filename))) {
String line;
while ((line = reader.readLine()) != null) {
content.append(line).append("\n");
}
} catch (IOException e) {
e.printStackTrace();
}
return content.toString();
}

// 复制文本文件
public static boolean copyFile(String sourceFilename, String targetFilename) {
try (BufferedReader reader = new BufferedReader(new FileReader(sourceFilename));
BufferedWriter writer = new BufferedWriter(new FileWriter(targetFilename))) {
String line;
while ((line = reader.readLine()) != null) {
writer.write(line);
writer.newLine();
}
return true;
} catch (IOException e) {
e.printStackTrace();
}
return false;
}

// 查询文本文件
public static boolean searchFile(String filename, String keyword) {
try (BufferedReader reader = new BufferedReader(new FileReader(filename))) {
String line;
while ((line = reader.readLine()) != null) {
if (line.contains(keyword)) {
return true;
}
}
} catch (IOException e) {
e.printStackTrace();
}
return false;
}

// 修改文本文件
public static boolean modifyFile(String filename, String oldString, String newString) {
try (BufferedReader reader = new BufferedReader(new FileReader(filename));
BufferedWriter writer = new BufferedWriter(new FileWriter(filename + ".temp"))) {
String line;
while ((line = reader.readLine()) != null) {
line = line.replace(oldString, newString);
writer.write(line);
writer.newLine();
}
} catch (IOException e) {
e.printStackTrace();
return false;
}

// 删除原文件，将临时文件重命名为原文件名
File originalFile = new File(filename);
if (!originalFile.delete()) {
return false;
}
File newFile = new File(filename + ".temp");
return newFile.renameTo(originalFile);
}
}

该程序提供了读取文本文件、复制文本文件、查询文本文件和修改文本文件的功能。你可以根据自己的需要调用这些方法来实现你的需求。  

### 回答3：
写一个可以实现文本文件的读入、复制、查询和修改的程序，可以使用Java语言来实现。以下是一个示例程序的全套代码：

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.util.Scanner;

public class TextFileManipulator {
private static final String FILE_PATH = "file.txt";

public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
String choice;

do {
System.out.println("请选择操作：");
System.out.println("1. 读取文件");
System.out.println("2. 复制文件");
System.out.println("3. 查询文件");
System.out.println("4. 修改文件");
System.out.println("0. 退出");

choice = scanner.nextLine();

switch (choice) {
case "1":
readFile();
break;
case "2":
copyFile();
break;
case "3":
searchFile();
break;
case "4":
modifyFile();
break;
}
} while (!choice.equals("0"));

scanner.close();
}

private static void readFile() {
try (BufferedReader reader = new BufferedReader(new FileReader(FILE_PATH))) {
String line;

System.out.println("文件内容：");

while ((line = reader.readLine()) != null) {
System.out.println(line);
}
} catch (IOException e) {
System.out.println("读取文件失败：" + e.getMessage());
}
}

private static void copyFile() {
try (BufferedReader reader = new BufferedReader(new FileReader(FILE_PATH));
BufferedWriter writer = new BufferedWriter(new FileWriter("copy.txt"))) {
String line;

while ((line = reader.readLine()) != null) {
writer.write(line);
writer.newLine();
}

System.out.println("文件复制成功");
} catch (IOException e) {
System.out.println("复制文件失败：" + e.getMessage());
}
}

private static void searchFile() {
try (BufferedReader reader = new BufferedReader(new FileReader(FILE_PATH));
Scanner scanner = new Scanner(System.in)) {
System.out.println("请输入要查询的关键字：");
String keyword = scanner.nextLine();
String line;
boolean found = false;

System.out.println("查询结果：");

while ((line = reader.readLine()) != null) {
if (line.contains(keyword)) {
System.out.println(line);
found = true;
}
}

if (!found) {
System.out.println("未找到匹配的内容");
}
} catch (IOException e) {
System.out.println("查询文件失败：" + e.getMessage());
}
}

private static void modifyFile() {
try (BufferedReader reader = new BufferedReader(new FileReader(FILE_PATH));
BufferedWriter writer = new BufferedWriter(new FileWriter("temp.txt"));
Scanner scanner = new Scanner(System.in)) {
System.out.println("请输入要修改的关键字：");
String keyword = scanner.nextLine();
System.out.println("请输入新内容：");
String newContent = scanner.nextLine();
String line;
boolean modified = false;

while ((line = reader.readLine()) != null) {
if (line.contains(keyword)) {
writer.write(newContent);
modified = true;
} else {
writer.write(line);
}
writer.newLine();
}

if (modified) {
System.out.println("文件修改成功");
} else {
System.out.println("未找到匹配的内容，文件未修改");
}
} catch (IOException e) {
System.out.println("修改文件失败：" + e.getMessage());
}

try {
// 删除原文件并将临时文件重命名为原文件名
java.nio.file.Files.delete(java.nio.file.Paths.get(FILE_PATH));
java.nio.file.Files.move(java.nio.file.Paths.get("temp.txt"), java.nio.file.Paths.get(FILE_PATH));
} catch (IOException e) {
System.out.println("重命名文件失败：" + e.getMessage());
}
}
}

这个程序首先提供了一个菜单供用户选择操作，然后根据用户选择执行不同的操作。程序可以读取文本文件的内容并打印到控制台，同时可以将文件复制到一个新的文件中。用户还可以输入关键字来查询文件中包含该关键字的行，并可以修改文件中包含关键字的行。修改文件后，原文件会被删除，临时文件将被重命名为原文件名。