如何在 Java 中打开 txt 文件并读取数字
声明：本页面是StackOverFlow热门问题的中英对照翻译，遵循CC BY-SA 4.0协议，如果您需要使用它，必须同样遵循CC BY-SA许可，注明原文地址和作者信息，同时你必须将它归于原作者（不是我）：StackOverFlow
原文地址: http://stackoverflow.com/questions/3806062/
Warning: these are provided under cc-by-sa 4.0 license. You are free to use/share it, But you must attribute it to the original authors (not me):
StackOverFlow
How to open a txt file and read numbers in Java
提问by nunos
How can I open a .txt file and read numbers separated by enters or spaces into an array list?
如何打开 .txt 文件并将由输入或空格分隔的数字读取到数组列表中？
采纳答案by dogbane
Read file, parse each line into an integer and store into a list:
读取文件，将每一行解析为一个整数并存储到一个列表中：
List<Integer> list = new ArrayList<Integer>();
File file = new File("file.txt");
BufferedReader reader = null;
try {
reader = new BufferedReader(new FileReader(file));
String text = null;
while ((text = reader.readLine()) != null) {
list.add(Integer.parseInt(text));
}
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} finally {
try {
if (reader != null) {
reader.close();
}
} catch (IOException e) {
}
}
//print out the list
System.out.println(list);
回答by Jigar Joshi
try{
BufferedReader br = new BufferedReader(new FileReader("textfile.txt"));
String strLine;
//Read File Line By Line
while ((strLine = br.readLine()) != null) {
// Print the content on the console
System.out.println (strLine);
}
//Close the input stream
in.close();
}catch (Exception e){//Catch exception if any
System.err.println("Error: " + e.getMessage());
}finally{
in.close();
}
This will read line by line,
这将逐行读取，
If your no. are saperated by newline char. then in place of
如果你没有。由换行符分隔。然后代替
System.out.println (strLine);
You can have
你可以有
try{
int i = Integer.parseInt(strLine);
}catch(NumberFormatException npe){
//do something
}
If it is separated by spaces then
如果用空格分隔，则
try{
String noInStringArr[] = strLine.split(" ");
//then you can parse it to Int as above
}catch(NumberFormatException npe){
//do something
}
回答by Igor G.
A much shorter alternative is below:
一个更短的替代方案如下：
Path filePath = Paths.get("file.txt");
Scanner scanner = new Scanner(filePath);
List<Integer> integers = new ArrayList<>();
while (scanner.hasNext()) {
if (scanner.hasNextInt()) {
integers.add(scanner.nextInt());
} else {
scanner.next();
}
}
A Scanner breaks its input into tokens using a delimiter pattern, which by default matches whitespace. Although default delimiter is whitespace, it successfully found all integers separated by new line character.
Scanner 使用分隔符模式将其输入分解为标记，默认情况下与空格匹配。虽然默认分隔符是空格，但它成功找到了所有由换行符分隔的整数。
回答by AdamSkywalker
Good news in Java 8 we can do it in one line:
Java 8 中的好消息我们可以在一行中完成：
List<Integer> ints = Files.lines(Paths.get(fileName))
.map(Integer::parseInt)
.collect(Collectors.toList());
回答by Ban
File file = new File("file.txt");
Scanner scanner = new Scanner(file);
List<Integer> integers = new ArrayList<>();
while (scanner.hasNext()) {
if (scanner.hasNextInt()) {
integers.add(scanner.nextInt());
}
else {
scanner.next();
}
}
System.out.println(integers);
回答by SAHIL SIKARWAR
import java.io.*;
public class DataStreamExample {
public static void main(String args[]){
try{
FileWriter fin=new FileWriter("testout.txt");
BufferedWriter d = new BufferedWriter(fin);
int a[] = new int[3];
a[0]=1;
a[1]=22;
a[2]=3;
String s="";
for(int i=0;i<3;i++)
{
s=Integer.toString(a[i]);
d.write(s);
d.newLine();
}
System.out.println("Success");
d.close();
fin.close();
FileReader in=new FileReader("testout.txt");
BufferedReader br=new BufferedReader(in);
String i="";
int sum=0;
while ((i=br.readLine())!= null)
{
sum += Integer.parseInt(i);
}
System.out.println(sum);
}catch(Exception e){System.out.println(e);}
}
}
OUTPUT:: Success 26
输出：成功 26
Also, I used array to make it simple.... you can directly take integer input and convert it into string and send it to file. input-convert-Write-Process... its that simple.
另外，我使用数组来简化....您可以直接获取整数输入并将其转换为字符串并将其发送到文件。输入-转换-写入-处理...就是这么简单。
