java - 在Java中写入txt中的特定行

Question

这是我的代码:

public static void modif(String name, String color, int k)
    {
        try {
        File input= new File("file1.txt");
        File output= new File("temp.txt");

        String correctLine = (String) FileUtils.readLines(input).get(k-3);

        BufferedReader br = new BufferedReader(new FileReader(input));
        BufferedWriter bw = new BufferedWriter(new FileWriter(output));
        String line="";


        while ((ligne = br.readLine()) != null){

            String lineConcat = line  + "\n";

         if(ligne.startsWith("\""+name+"\"")){

         System.out.println(correctLine); // i can display the line to change

             bw.write("\"" + name + "\"" + ": " + "\"" + color + "\"" + "\n"); // this is the way i replace my line
             System.out.println("Awesome !");
             bw.flush();
         }else{
             bw.write(lineConcat);
             bw.flush();
         }
        }
        bw.close();
        br.close();

        output.renameTo(new File("file2.txt"));

        } catch (IOException e) {
            e.printStackTrace();
        }

}

基本上我想在检测到条件时替换特定行。我知道要更改哪一行，但不知道如何替换它。因为现在我只能检测行的开头并更改当前行而不是前一行。

我尝试使用 FileUtils.writeStringToFile 但它不起作用，所以我来这里寻求帮助:(

谢谢大家!

编辑:我的输入是这样的:

{
      "type": "Feature",
      "geometry": {
        "type": "Polygon",
        "coordinates": [
          [
            [
              6.07721374522497,
              43.08716485432151
            ],
            [
              6.051202617426629,
              43.07969629888752
            ],
            [
              6.032563261594762,
              43.07758570385911
            ]
          ]
        ]
      },
      "properties": {
        "_storage_options": {
"color": "Orange"
        },
"name": "CARQUEIRANNE"
      }
    }

我实际上正在做的是，当我找到“name”行:“CAREQUEIRANNE”时，我想替换他的颜色属性，所以我必须转到当前行 - 3，我真的不知道该怎么做它

编辑2:

我的方法是这样调用的:

                BufferedReader in2 = new BufferedReader(new FileReader("file1.txt"));
				String line;
				String lineConcat = null;
				int k=1;
				
				while ((line = in2.readLine()) != null)
				{

					
					lineConcat = line + "\n";

					String myPattern = tabCity[21];
					Pattern p = Pattern.compile(myPattern);
					Matcher m = p.matcher(lineConcat);
					//Matcher m2 = p2.matcher(lineConcat);
					if (m.find()){

						System.out.println("Found !");
						System.out.println(k);
						
						modif("color", "Orange", k);
						
						
					}
					else
					{
						System.out.println("Not Found");
					}
					
					k++;

				}
				in2.close();

当我发现我的模式与文件中的研究相匹配时，我调用我的函数来替换城市的颜色属性

编辑3:

@BrettWalker 这是新代码:

public static void modif(String nom, String color, int k)
	{
		try {
		File input = new File("file1.txt");
		File output = new File("temp.txt");
		
		BufferedReader br = new BufferedReader(new FileReader(input));
		BufferedWriter bw = new BufferedWriter(new FileWriter(output));
		String line="";

		Stack st = new Stack();
		
		st.push(br.readLine());
		st.push(br.readLine());
		st.push(br.readLine());
		
		while ((ligne = br.readLine()) != null){
			
			String ligneConcat = ligne  + "\n";
			
			st.push(ligneConcat);
			
			String oldLine = (String) st.pop();

		 if(ligne.startsWith("\""+nom+"\"")){
			 

			 oldLine = "\"" + nom + "\"" + ": " + "\"" + color + "\"" + "\n";

		 }
		 	bw.write(oldLine);
		}
		
		
		bw.write((int) st.pop());
		bw.write((int) st.pop());
		bw.write((int) st.pop());
		
		bw.close();
		br.close();
		 
		output.renameTo(new File("file2.txt"));
		
		} catch (IOException e) {
			e.printStackTrace();
		}

}

Answer 1

在 Java 中，您需要使用队列(缓冲区)来临时保存文件的一小段，以便您能够检测到何时并允许您更改相应的行。

不是立即写出该行，而是将该行插入队列(缓冲区)并从队列中弹出下一个项目。如果刚刚弹出的行是要更改的行，则将修改后的行写入文件，否则将原始行写入文件。

一些糟糕的伪代码来帮助表达这个想法。

// Open up the readers/writers

// Prime the queue with the first few line of the file.
// Need to add safeguard to protect against small files!!
queue.push(br.readLine());
queue.push(br.readLine());
queue.push(br.readLine());

while ((line = br.readLine()) != null) {
    String lineConcat = line  + "\n";

    queue.push(lineConcat);

    String oldLine = queue.pop();

    if (line.startsWith("\""+name+"\"")) {
         oldLine = < Modify oldLine >
    }

    bw.write(oldLine)
}

// Empty the queue
bw.write(queue.pop());
bw.write(queue.pop());
bw.write(queue.pop());

// Close the readers/writer