如何修复这个java.lang.OutOfMemoryError:java堆空间？

我得到一个java.lang.OutOfMemoryError:java堆空间。我不确定我做错了什么。这是我的密码：

StringBuffer finalString = new StringBuffer();

    try {
        BufferedReader br = new BufferedReader(new FileReader("collegeData 2.txt"));
        StringBuffer returnFile = new StringBuffer();
        returnFile.append(br.readLine() + br.readLine());
        ArrayList<String> allData = new ArrayList<String>();

        boolean completedFirstSection = false;
        int count = 2;
        String addString = "";  

        String nextLine;

        while ((nextLine=br.readLine())!=null) {
            if(count < 990) {
                addString += nextLine;
                count++;
            } else {
                String sub = nextLine.substring(16);
                sub = sub.substring(0, sub.length());

                addString = sub + ":{" + nextLine + "," + addString.substring(0, addString.length()-2) + br.readLine();
                br.readLine();
                allData.add(addString);
                count = 2;
            }
        }
        allData.add("}}]");
        System.out.println("here");
        System.out.println(returnFile.toString());
        finalString = returnFile;
        br.close();
    } catch (IOException e) {
        e.printStackTrace();
    }

java:31是上面的'addString+=nextLine'

---

提前感谢您的帮助

谢谢您对twain249的支持！将我的代码更改为此后，我的程序运行得很快，非常完美

StringBuffer finalString = new StringBuffer();

    try {
        BufferedReader br = new BufferedReader(new FileReader("collegeData 2.txt"));
        StringBuffer returnFile = new StringBuffer();
        returnFile.append(br.readLine() + "\n" + br.readLine() + "\n");

        boolean completedFirstSection = false;
        int count = 2;
        StringBuffer addString = new StringBuffer();

        String nextLine;

        while ((nextLine=br.readLine())!=null) {
            if(count < 990) {
                addString.append(nextLine + "\n");
                count++;
            } else {
                String sub = nextLine.substring(16);
                sub = sub.substring(0, sub.length());

                // addString = sub + ":{" + nextLine + "," + addString.substring(0, addString.length()-2) + br.readLine();
                returnFile.append(sub + ":{" + nextLine + "," + "\n");
                returnFile.append(addString.substring(0, addString.length()-2) + "\n");
                returnFile.append(br.readLine() + "\n");
                addString.setLength(0);
                count = 2;
                br.readLine();
            }
        }
        returnFile.append("}}]");
        finalString = returnFile;
        br.close();
    } catch (IOException e) {
        e.printStackTrace();
    }

StringBuffer finalString=new StringBuffer（）；
试一试{
BufferedReader br=新的BufferedReader（新文件读取器（“collegeData 2.txt”）；
StringBuffer returnFile=新的StringBuffer（）；
returnFile.append（br.readLine（）+“\n”+br.readLine（）+”\n”）；
布尔completedFirstSection=false；
整数计数=2；
StringBuffer addString=新的StringBuffer（）；
字符串下一行；
而（（nextLine=br.readLine（））！=null）{
如果（计数<990）{
addString.append（nextLine+“\n”）；
计数++；
}否则{
String sub=nextLine.substring（16）；
sub=sub.substring（0，sub.length（））；
//addString=sub+“：{“+nextLine+”，“+addString.substring（0，addString.length（）-2）+br.readLine（）；
append（sub+“：{+nextLine+”，“+”\n”）；
returnFile.append（addString.substring（0，addString.length（）-2）+“\n”）；
returnFile.append（br.readLine（）+“\n”）；
addString.setLength（0）；
计数=2；
br.readLine（）；
}
}
returnFile.append（“}}]”；
finalString=returnFile；
br.close（）；
}捕获（IOE异常）{
e、 printStackTrace（）；
}

不确定这是否是错误的原因，但如果需要同步，您应该使用

StringBuilder

，或者

StringBuffer

，而不是

addString

的

String

<代码>字符串s是不可变的，因此每次追加都需要分配一个新对象并进行复制。哦，这是一个很好的观点！让我试一试，我是否应该创建一个字符串缓冲区，然后每次清除该字符串缓冲区？

StringBuffer finalString = new StringBuffer();

    try {
        BufferedReader br = new BufferedReader(new FileReader("collegeData 2.txt"));
        StringBuffer returnFile = new StringBuffer();
        returnFile.append(br.readLine() + "\n" + br.readLine() + "\n");

        boolean completedFirstSection = false;
        int count = 2;
        StringBuffer addString = new StringBuffer();

        String nextLine;

        while ((nextLine=br.readLine())!=null) {
            if(count < 990) {
                addString.append(nextLine + "\n");
                count++;
            } else {
                String sub = nextLine.substring(16);
                sub = sub.substring(0, sub.length());

                // addString = sub + ":{" + nextLine + "," + addString.substring(0, addString.length()-2) + br.readLine();
                returnFile.append(sub + ":{" + nextLine + "," + "\n");
                returnFile.append(addString.substring(0, addString.length()-2) + "\n");
                returnFile.append(br.readLine() + "\n");
                addString.setLength(0);
                count = 2;
                br.readLine();
            }
        }
        returnFile.append("}}]");
        finalString = returnFile;
        br.close();
    } catch (IOException e) {
        e.printStackTrace();
    }