Question

所以，我正在尝试为即将到来的决赛练习，我只是为了娱乐和学习而进行随机编码。今晚我偶然发现了我以前从未见过的错误代码。我的代码似乎没有进入for循环，然后弹出错误消息。有任何想法吗？谢谢！

Please enter a sentence
Testing the program
You entered :
testing the program

Exception in thread "main" java.lang.OutOfMemoryError: Java heap space
at java.util.Arrays.copyOf(Arrays.java:3332)
at java.lang.AbstractStringBuilder.expandCapacity(AbstractStringBuilder.java:137)    
at java.lang.AbstractStringBuilder.ensureCapacityInternal(AbstractStringBuilder.java:121)
at java.lang.AbstractStringBuilder.append(AbstractStringBuilder.java:421)
at java.lang.StringBuilder.append(StringBuilder.java:136)
at FinalStudy.main(FinalStudy.java:22)

public static void main(String[] args) 
{            
    Scanner input=new Scanner(System.in);            
    System.out.println("Please enter a sentence");

    String sentence=input.nextLine();
    sentence=sentence.toLowerCase();

    System.out.println("You entered : \n" + sentence);
    //Doesn't seem to make it to this loop because it only prints the initial sentence
    for (int i=0; i<sentence.length(); i++)
    {                 
        if (sentence.charAt(i)=='a' || sentence.charAt(i)=='e' || sentence.charAt(i)=='i')
        {
            sentence=sentence.substring(0,i) + "*" + sentence.substring(0,(i+1));        
        }
    }

   System.out.println("This is your new sentence: \n" + sentence);                       
}

Answer 1

TLDR：你在这里有一个无限循环，它会扩展String'句子'，直到你的内存不足为止。但我不会告诉你如何解决你的问题。

此外，您需要学习如何在程序中使用断点和打印语句进行调试。一个简单的谷歌搜索就足够了。

解释为什么它不起作用：

Imagine that I input the sentence "abc" and let's go through the for loop.
First, i = 0, and the length of 'sentence' = 3.
    sentence.charAt(0) == 'a' is true
    thus 'sentence' is now set to be the substring from 0 up to 0 (nothing),
    plus '*', plus the substring from 0, up to 1 ("a").
    Now the String 'sentence' is set to "*a".
i = 1, length = 2,
    sentence.charAt(1) == 'a' is true
    'sentence' is now set to be the substring from 0 up to 1 ("*"),
    plus '*', plus the substring from 0 up to 2 ("*a");
    Now the String 'sentence' is set to ***a
The for loop continues in this manner, doubling the length of the string
'sentence' whenever the variable i reaches sentence.length()-1. Eventually the
computer runs out of memory because it cannot store an infinite length string
and the program crashes.

一些提示：当您单击IDE中的行号时，会导致出现“断点”。这意味着如果您以“调试模式”运行程序，解释器将在该行暂停并允许您查看某些信息，例如某些变量的值。调试时的另一个技巧是使用print语句显示有关代码中发生的事情的信息，通常以这种方式显示变量。

PS每个人都曾经这样问过问题，所以不要气馁，因为你无法弄清问题。将来使用上面的建议尝试先调试，然后尝试解决方案的其他来源。通常，像这样的简单错误是问题的原因，可以通过调试找到它们。

Answer 2

使用替换方法

                Socket socket = serverSocket.accept();
                InputStream iStream = socket.getInputStream();                 ;
                String currentDateandTime = sdf.format(new Date());



                //   int filenamelen =iStream.read();

                //image Name
                byte[] countBuf = new byte[8];
                //  byte[] imageNameByte = new byte[7];
                iStream.read(countBuf);
                //iStream.read(imageNameByte,0,7);
                readTxt = new String(countBuf);
                // imageName= new String(imageNameByte);
                int size = Integer.parseInt(readTxt);


                //Send byte array                                      
                 senderSocket.Send(countBuf, 0, data.Length, SocketFlags.None);new File(Environment.getExternalStorageDirectory() + File.separator + "DCIM" + File.separator + "SPARCS" + File.separator + folderName + File.separator + fileName).mkdirs();
                Log.e("TCP", "Create Drkt");
                //Create Image(File)

                new File(Environment.getExternalStorageDirectory() + File.separator + "DCIM" + File.separator + "SPARCS" + File.separator + folderName + File.separator + fileName, imageName + ".jpg").createNewFile();
                Log.e("TCP", "Create Img");

                try {
                    FileOutputStream fOutputStream = new FileOutputStream(Environment.getExternalStorageDirectory() + File.separator + "DCIM" + File.separator + "SPARCS" + File.separator + folderName + File.separator + fileName + File.separator + imageName + ".jpg");
                    BufferedOutputStream BufOutputStream = new BufferedOutputStream(fOutputStream);
                    byte[] aByte = new byte[size];
                    int byteRead;
                    //   int bytesRead = iStream.read(aByte);
                    //Read from server
                    while ((byteRead = iStream.read(aByte)) > 0) {
                        Log.e("TCP", "Save to file");//Write to file
                        BufOutputStream.write(aByte, 0, byteRead);
                    }
                    publishProgress();
                    notifyID++;
                    // String imageUri =Environment.getExternalStorageDirectory() + File.separator + "myDirectory" + File.separator + readTxt + File.separator+currentDateandTime+".jpg";
                    BufOutputStream.flush();
                    BufOutputStream.close();
                    socket.close();
                } catch (Exception ex) {
                    ex.printStackTrace();
                }
            }
        } catch (Exception e) {
            Log.e("TCP", "C: Error", e);
        }

Answer 3

很简单：

String str = "abciabehgitye";
str = str.replaceAll("[aei]", "*");
System.out.println("str = " + str); // str = *bc**b*hg*ty*

Answer 4

for循环中sentence的修改是错误的，它会改变（增加）字符串的长度，导致无限的循环。

按如下方式更改：

if (sentence.charAt(i)=='a' || sentence.charAt(i)=='e' || sentence.charAt(i)=='i') {     

     sentence = sentence.substring(0,i) + "*" + sentence.substring(i+1,sentence.length());

     }

这将输出正确的结果。

您也可以使用字符串replace / replaceAll方法来获得结果。

我正在尝试制作一个简单的程序，以取代＆＃39; a＆＃39; e＆＃39;＆＃39; i＆＃39;用＆＃34; *＆＃34;符号，但我得到此错误代码

4 个答案: