我不知道有一种简单的方法可以做到这一点，但是有一种相当复杂的方法可以做到这一点，即从文件中读取文本，对其进行编辑，然后用编辑后的文本覆盖文件。首先，您需要将文件逐行读取到数组中：
package addtext;
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.util.logging.Level;
import java.util.logging.Logger;
/**
*
* @author Dan300
*/
public class AddText {
File yourFile = new File("YourFileHere.txt"); //add the name of your file in the brackets
int numLines; //this will store the number of lines in the file
String[] lines; //the lines of text that make up the file will be stored here
public AddText() {
numLines = getNumberLines(yourFile);
lines = new String[numLines];//here we set the size of the array to be the same as the number of lines in the file
for(int count = 0; count < numLines; count++) {
lines[count] = readLine(count,yourFile);//here we set each string in the array to be each new line of the file
}
doSomethingToStrings();
}
public static void main(String[] args) {
new AddText();
}
上面的代码基本上通过调用下面的方法（返回文件中文本的行数）来设置一个数组以包含与文件中的行数一样多的字符串...：
public int getNumberLines(File aFile) {
int numLines = 0;
try {
BufferedReader input = new BufferedReader(new FileReader(aFile));
try {
String line = null;
while (( line = input.readLine()) != null){ //ReadLine returns the contents of the next line, and returns null at the end of the file.
numLines++;
}
}
finally {
input.close();
}
}
catch (IOException ex){
ex.printStackTrace();
}
return numLines;
}
...然后通过为每一行调用此方法来设置数组以包含文件中的文本：
public String readLine(int lineNumber, File aFile) {
String lineText = "";
try {
BufferedReader input = new BufferedReader(new FileReader(aFile));
try {
for(int count = 0; count < lineNumber; count++) {
input.readLine(); //ReadLine returns the contents of the next line, and returns null at the end of the file.
}
lineText = input.readLine();
}
finally {
input.close();
}
}
catch (IOException ex){
ex.printStackTrace();
}
return lineText;
}
阅读完文本文件后，您现在需要使用.concat()将两个字符串连接在一起的方法对字符串做一些事情。此代码将执行问题中的示例：
public void doSomethingToStrings() {
try {
lines[0] = lines[0].concat(" ddd"); //this joins the two strings lines[0] and " ddd"
} catch (ArrayIndexOutOfBoundsException ex) { // I have added a try{}catch{} block so that if there is not as many lines in the file as expected, the code will still continue.
}
try {
lines[1] = lines[1].concat(" hhh");
} catch (ArrayIndexOutOfBoundsException ex) {
}
try {
writeFile(yourFile);
} catch (FileNotFoundException ex) {
} catch (IOException ex) {
Logger.getLogger(AddText.class.getName()).log(Level.SEVERE, null, ex);
}
}
在此之后，它调用writeFile()将数组写入文件的方法。如果您想让代码更灵活，您可能希望添加另一个构造函数来将不同的数组写入文件：
public void writeFile(File aFile) throws FileNotFoundException, IOException {
if (aFile == null) {
throw new IllegalArgumentException("File should not be null.");
}
if (!aFile.exists()) {
throw new FileNotFoundException ("File does not exist: " + aFile);
}
if (!aFile.isFile()) {
throw new IllegalArgumentException("Should not be a directory: " + aFile);
}
if (!aFile.canWrite()) {
throw new IllegalArgumentException("File cannot be written: " + aFile);
}
BufferedWriter output = new BufferedWriter(new FileWriter(aFile));
try {
for(int count = 0; count < numLines; count++) {
output.write(lines[count]);
if(count != numLines-1) {// This makes sure that an extra new line is not inserted at the end of the file
output.newLine();
}
}
}
finally {
output.close();
}
}
要回答您的第二个问题，可以在一行中插入一个或多个单词，方法是使用StringTokenizer将字符串拆分为单词，然后在文本行中插入一个新单词。StringTokenizer 将字符串拆分为单词，调用 $Tokenizer1.nextToken() 返回字符串中的下一个单词。这是一个示例，其结果在您的问题中指定：
public void doSomethingElseToStrings() {
try{
StringTokenizer splitString1 = new StringTokenizer(lines[0]);
newLines[0] = splitString1.nextToken();
for(int count=0;count<=splitString1.countTokens();count++) {
if(count == 0) {
newLines[0] = newLines[0].concat(" 111");
}
newLines[0] = newLines[0].concat(" ");
newLines[0] = newLines[0].concat(splitString1.nextToken());
}
} catch(ArrayIndexOutOfBoundsException ex) {
}
try {
StringTokenizer splitString2 = new StringTokenizer(lines[1]);
newLines[1] = splitString2.nextToken();
for(int count=0;count<=splitString2.countTokens();count++) {
if(count == 1) {
newLines[1] = newLines[1].concat(" 222");
}
newLines[1] = newLines[1].concat(" ");
newLines[1] = newLines[1].concat(splitString2.nextToken());
}
} catch(ArrayIndexOutOfBoundsException ex) {
}
try {
writeFile(yourFile);
} catch (FileNotFoundException ex) {
} catch (IOException ex) {
Logger.getLogger(AddText.class.getName()).log(Level.SEVERE, null, ex);
}
}
但是，要使其与其余代码一起使用，您必须编辑这些部分：
public class AddText {
String[] newLines; // <<add
File yourFile = new File("YourFileHere.txt"); //add the name of your file in the brackets
int numLines;
String[] lines;
public AddText() {
...
//doSomethingToStrings(); <<delete
doSomethingElseToStrings(); // <<add
}
public void writeFile(File aFile) throws FileNotFoundException, IOException {
...
//output.write(lines[count]); <<delete
output.write(newLines[count]); // <<add
...
}
使用该doSomethingToStrings()方法更改文件：
aaa bbb ccc
eee fff ggg
(other text)
对此：
aaa bbb ccc ddd
eee fff ggg hhh
(other text remains the same)
使用该doSomethingElseToStrings()方法将文件更改为：
aaa 111 bbb ccc
ddd eee 222 fff
(other text remains the same)
我希望这对你有用！
以下是使用Guava的方法：
List<String> lines = Files.readLines(new File("myfile.txt"), Charsets.UTF_8);
StringBuilder output = new StringBuilder();
for(String line : lines) {
String newLine = addNeededStringToLine(line);
output.append(newLine);
}
Files.write(output, new File("myfile2.txt"), Charsets.UTF_8);
就那么简单
关于插入行，您可以简单地将整行拆分为单独的字符串，然后在它们之间放置要插入的值。使用类似的东西：
String line = "a b c" ;
String[] split = line.split(" ");
for (int i = 0; i < split.length; i++) {
String string = split[i];
System.out.println(string);
if(string.equals("b")) {
//some insterting
}
}
参考：