Java - 加载文件，替换字符串，保存 [英] Java - Load file, replace string, save

问题描述

我有一个程序从用户文件加载行，然后选择字符串的最后部分（这将是一个int）

这是它保存的样式in：

  nameOfValue = 0 
 nameOfValue2 = 0 
  

等等。我已经确定了值 - 我通过打印进行调试。

  if（nameOfValue.equals（type））{
 System.out.println（nameOfValue +等于+ type）; 
 value.replace（value，Integer.toString（Integer.parseInt（value）+1））; 
} 
  

如何重新保存它？我已经尝试了bufferedwriter，但它只是擦除文件中的所有内容。 我的建议是，保存原始的所有内容文件（无论是在内存中还是在临时文件中，我都会在内存中执行），然后重新写入，包括修改。我相信这会工作：
$ b $ pre $ public static void replaceSelected（File file，String type）throws IOException {

//我们需要存储所有的行
List< String> lines = new ArrayList< String>（）;

//首先读取文件并保存更改
BufferedReader in = new BufferedReader（new FileReader（file））;
String line = in.readLine（）;
while（line！= null）{
if（line.startsWith（type））{
String sValue = line.substring（line.indexOf（'='）+ 1）.trim （）;
int nValue = Integer.parseInt（sValue）;
line = type +=+（nValue + 1）;
}
lines.add（line）;
line = in.readLine（）;
}
in.close（）;

//现在，再次使用变化写入文件
PrintWriter out = new PrintWriter（file）;
for（String l：lines）
out.println（l）;
out.close（）;






你可以调用这个方法，要修改的文件和要选择的值的名称：



  replaceSelected（new File（test.txt ），nameOfValue2）; 
  




I have a program that loads lines from a user file, then selects the last part of the String (which would be an int)

Here's the style it's saved in:

nameOfValue = 0
nameOfValue2 = 0

and so on. I have selected the value for sure - I debugged it by printing. I just can't seem to save it back in.

if(nameOfValue.equals(type)) {
        System.out.println(nameOfValue+" equals "+type);
            value.replace(value, Integer.toString(Integer.parseInt(value)+1));
        }

How would I resave it? I've tried bufferedwriter but it just erases everything in the file.

解决方案

My suggestion is, save all the contents of the original file (either in memory or in a temporary file; I'll do it in memory) and then write it again, including the modifications. I believe this would work:

public static void replaceSelected(File file, String type) throws IOException {

    // we need to store all the lines
    List<String> lines = new ArrayList<String>();

    // first, read the file and store the changes
    BufferedReader in = new BufferedReader(new FileReader(file));
    String line = in.readLine();
    while (line != null) {
        if (line.startsWith(type)) {
            String sValue = line.substring(line.indexOf('=')+1).trim();
            int nValue = Integer.parseInt(sValue);
            line = type + " = " + (nValue+1);
        }
        lines.add(line);
        line = in.readLine();
    }
    in.close();

    // now, write the file again with the changes
    PrintWriter out = new PrintWriter(file);
    for (String l : lines)
        out.println(l);
    out.close();

}

And you'd call the method like this, providing the File you want to modify and the name of the value you want to select:

replaceSelected(new File("test.txt"), "nameOfValue2");

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