这个程序输入“你好我的名字是bob”并向后吐出来。我真的需要帮助,使程序读入文本文件并向后吐出文本文件。提前致谢!
public class Recursion
{
public static void main(String[] args) throws FileNotFoundException {
System.out.println(printBackwards("hello my name is bob"));
}
public static String printBackwards(String s){
if(s.length() <= 1)
return s;
else
return printBackwards(s.substring(1,s.length()))+s.charAt(0);
}
}
答案 0 :(得分:0)
根据问题的评论,这将读取一个名为input.txt的文件,并使用您的方法将其保存到名为output.txt的新文件中,以反转String
。
input.txt中的所有行首先添加到List
。
然后从最后一个元素向后迭代List
,并在每次迭代时将反转的String
写入output.txt。
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileWriter;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import java.util.ListIterator;
import java.util.Scanner;
public class Example {
public static void main(String[] args) throws IOException {
try (BufferedWriter writer = new BufferedWriter(new FileWriter("output.txt"))) {
Scanner scanner = new Scanner(new File("input.txt"));
List<String> fileContents = new ArrayList<>();
while (scanner.hasNextLine()) {
fileContents.add(scanner.nextLine());
}
ListIterator<String> it = fileContents.listIterator(fileContents.size());
while (it.hasPrevious()) {
writer.write(printBackwards(it.previous()));
writer.newLine();
}
}
}
public static String printBackwards(String s) {
if (s.length() <= 1) {
return s;
} else {
return printBackwards(s.substring(1, s.length())) + s.charAt(0);
}
}
}
但是,如果您只想将其显示到标准输出,则可以将其调整为以下内容:
import java.io.File;
import java.io.FileNotFoundException;
import java.util.ArrayList;
import java.util.List;
import java.util.ListIterator;
import java.util.Scanner;
public class Example {
public static void main(String[] args) throws FileNotFoundException {
Scanner scanner = new Scanner(new File("input.txt"));
List<String> fileContents = new ArrayList<>();
while (scanner.hasNextLine()) {
fileContents.add(scanner.nextLine());
}
ListIterator<String> it = fileContents.listIterator(fileContents.size());
while (it.hasPrevious()) {
System.out.println(printBackwards(it.previous()));
}
}
public static String printBackwards(String s) {
if (s.length() <= 1) {
return s;
} else {
return printBackwards(s.substring(1, s.length())) + s.charAt(0);
}
}
}
或者正如我之前在评论中所说的那样,您可以一次性阅读整个文件并将其反转:
import java.io.File;
import java.io.FileNotFoundException;
import java.util.Scanner;
public class Example {
public static void main(String[] args) throws FileNotFoundException {
System.out.println(printBackwards(new Scanner(new File("file.txt")).useDelimiter("\\Z").next()));
}
public static String printBackwards(String s) {
if (s.length() <= 1) {
return s;
} else {
return printBackwards(s.substring(1, s.length())) + s.charAt(0);
}
}
}
答案 1 :(得分:-1)
这应该按预期工作。我假设在filename_in.txt
你只有一行,否则你必须循环(我允许你这样做作为练习):
public static void main(String[] args){
Scanner in = null;
PrintWriter writer = null;
try{
in = new Scanner(new FileReader("filename_in.txt"));
writer = new PrintWriter("filename_out.txt");
writer.println(printBackwards(in.nextLine()));
} catch (Exception e) {
e.printStackTrace();
}
finally {
in.close();
writer.close();
}
}
答案 2 :(得分:-1)
使用此代码从文本文件中获取要反转的字符串:
try{
String myString;
BufferedReader input = new BufferedReader(new FileReader("Filepath.txt");
while((myString = input.readLine()) != null){}
}
catch(FileNotFoundException ex){
//Error Handler Here
}
catch(IOException ex){
//Error Handler Here
} finally {
try{
if(br != null) br.close();
}
catch(IOException ex){
ex.printStackTrace();
}
}
不要忘记导入:
import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;
import java.io.FileNotFoundException