在java中使用大字符串时StringBuilder内存不足错误 [英] StringBuilder out of memory error when working with large strings in java

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问题描述

我从字符串测试+ = str; 其中 test 成千上万的字符成倍增长。运行需要45分钟，可能是因为创建了大字符串并删除了垃圾。然后，我将这样的输入交错，这使它达到30秒。

I went from String test += str; where test grew exponentially large with thousands and thousands of characters. It took 45 minutes to run, probably from creating large strings and deleting garbage. I then staggered the input like this which brought it to 30 seconds.

这似乎是一种便宜的方式，但效果很好：

This seems like the cheap way to do it, but it worked well:

  if (secondDump.length() > 50)
  {
     intermedDump = intermedDump + secondDump;
     secondDump = "";
  }      

  if (intermedDump.length() > 100)
  {
     thirdDump = thirdDump + intermedDump;
     intermedDump = "";
  }
  if (thirdDump.length() > 500)
  {
     fourthDump = fourthDump + thirdDump;
     thirdDump = "";
  }
  if (fourthDump.length() > 1000)
  {
     fifthDump = fifthDump + fourthDump;
     fourthDump = "";
  }
  //with just this and not sixth.  Runtime>>>> : 77343
  if (fifthDump.length() > 5000)
  {
     sixthDump = sixthDump + fifthDump;
     fifthDump = "";
  }
  //with just this.  Runtime>>>> : 35903Runtime>>>> : 33780
  if (sixthDump.length() > 10000)
  {
     fillerDump = fillerDump + sixthDump;
     sixthDump = "";
  }

然后我发现 StringBuilder 存在，我一直在尝试使用它，因为用它替换所有的字符串操作。

I then discovered that StringBuilder exists, and I've been trying to use it since, replacing all string operations with it.

问题是，我不断收到带有java内存堆溢出的 java.lang.OutOfMemoryError 。我认为字符串太长了，无法作为 StringBuilder 对象存储在内存中，因为它占用了我以前的代码在崩溃之前所做的大约1/50的进度内存错误。它只能使用不到一千个字符。

The problem is, I keep getting an java.lang.OutOfMemoryError with a java memory heap overflow. I think the string is just too long to store in memory as a StringBuilder object, because it makes about 1/50th of the progress that my previous code did before crashing with an out of memory error. It's only working with maybe under a thousand characters.

为什么一个字符串可以保存整个输出，这不能接近？另外，如果我将文本追加到 JTextPane ，那需要多少内存？如果我将 StringBuilder 内容转储到 JTextpane 并继续追加并清除 StringBuilder 这似乎也不起作用。

Why can a string hold the entire output and this can't come close? Also, if I append text to JTextPane, how much memory does that need? If I dump the StringBuilder contents to JTextpane and keep appending and clearing StringBuilder that doesn't seem to work either.

这是现有代码。 Page只是一个被传递的对象：

Here is the existing code. Page is just an object being passed:

protected void concatPlates(page PageA) throws IOException
{
   if (backend.isFirstPage == false)
   {
      frontend.fillOutputPane("\n                                 " +
         "                                               \n", PageA);
      frontend.fillOutputPane("                                 " +
         "                                               \n", PageA);
      frontend.fillOutputPane("                                 " +
         "                                               \n", PageA);
   }
   for (int i = 0; i < PLATELEN-1; i++)
   {

      if (arrLeftCol[i].length() == 0)
      {
         /////////////////////////////////////////////////////////
         /////////////////////////////////////////////////////////
         frontend.fillOutputPane(arrLeftCol[i].append(
           arrRightCol[i]));
      }
     else
     {
        PageA.tempStrBuff = new StringBuilder(arrLeftCol[i].substring(0,40));
        frontend.fillOutputPane(PageA.tempStrBuff.append(arrRightCol[i]));
     }
     arrLeftCol[i].append("");
     arrRightCol[i].append("");

     backend.isFirstPage = false;
  }
}


//this is the frontend class
public static void fillOutputPane(String s, page PageA)
{
   fillOutputPane(PageA.getStrBuf());
}
public static void fillOutputPane(StringBuilder stringBuild)
{
  try
  {
     str.append(stringBuild);
  }
  catch (java.lang.OutOfMemoryError e)
  {
     System.out.println((str.length() * 16) /8);
     //System.out.println(str);
     System.out.println("out of memory error");
     System.exit(0);
  }
}

这是错误：

Exception in thread "AWT-EventQueue-0" java.lang.OutOfMemoryError: Java heap space
at java.util.Arrays.copyOf(Unknown Source)
at java.lang.AbstractStringBuilder.expandCapacity(Unknown Source)
at java.lang.AbstractStringBuilder.append(Unknown Source)
at java.lang.StringBuilder.append(Unknown Source)
at java.lang.StringBuilder.append(Unknown Source)
at backend.fill(backend.java:603)
at frontend$openL.actionPerformed(frontend.java:191)
at javax.swing.AbstractButton.fireActionPerformed(Unknown Source)
at javax.swing.AbstractButton$Handler.actionPerformed(Unknown Source)
at javax.swing.DefaultButtonModel.fireActionPerformed(Unknown Source)
at javax.swing.DefaultButtonModel.setPressed(Unknown Source)
at javax.swing.AbstractButton.doClick(Unknown Source)
at javax.swing.plaf.basic.BasicMenuItemUI.doClick(Unknown Source)
at javax.swing.plaf.basic.BasicMenuItemUI$Handler.mouseReleased(Unknown Source)
at java.awt.Component.processMouseEvent(Unknown Source)
at javax.swing.JComponent.processMouseEvent(Unknown Source)
at java.awt.Component.processEvent(Unknown Source)
at java.awt.Container.processEvent(Unknown Source)
at java.awt.Component.dispatchEventImpl(Unknown Source)
at java.awt.Container.dispatchEventImpl(Unknown Source)
at java.awt.Component.dispatchEvent(Unknown Source)
at java.awt.LightweightDispatcher.retargetMouseEvent(Unknown Source)
at java.awt.LightweightDispatcher.processMouseEvent(Unknown Source)
at java.awt.LightweightDispatcher.dispatchEvent(Unknown Source)
at java.awt.Container.dispatchEventImpl(Unknown Source)
at java.awt.Window.dispatchEventImpl(Unknown Source)
at java.awt.Component.dispatchEvent(Unknown Source)
at java.awt.EventQueue.dispatchEventImpl(Unknown Source)
at java.awt.EventQueue.access$000(Unknown Source)
at java.awt.EventQueue$1.run(Unknown Source)
at java.awt.EventQueue$1.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)

我认为这就是堆栈跟踪：

I think this is what a stack trace is:

java.lang.Exception: Stack trace
at java.lang.Thread.dumpStack(Unknown Source)
at frontend.fillOutputPane(frontend.java:385)
at page.concatPlates(page.java:105)
at backend.setPlate(backend.java:77)
at backend.fill(backend.java:257)
at frontend$openL.actionPerformed(frontend.java:191)
at javax.swing.AbstractButton.fireActionPerformed(Unknown Source)
at javax.swing.AbstractButton$Handler.actionPerformed(Unknown Source)
at javax.swing.DefaultButtonModel.fireActionPerformed(Unknown Source)
at javax.swing.DefaultButtonModel.setPressed(Unknown Source)
at javax.swing.AbstractButton.doClick(Unknown Source)
at javax.swing.plaf.basic.BasicMenuItemUI.doClick(Unknown Source)
at javax.swing.plaf.basic.BasicMenuItemUI$Handler.mouseReleased(Unknown Source)
at java.awt.Component.processMouseEvent(Unknown Source)
at javax.swing.JComponent.processMouseEvent(Unknown Source)
at java.awt.Component.processEvent(Unknown Source)
at java.awt.Container.processEvent(Unknown Source)
at java.awt.Component.dispatchEventImpl(Unknown Source)
at java.awt.Container.dispatchEventImpl(Unknown Source)
at java.awt.Component.dispatchEvent(Unknown Source)
at java.awt.LightweightDispatcher.retargetMouseEvent(Unknown Source)
at java.awt.LightweightDispatcher.processMouseEvent(Unknown Source)
at java.awt.LightweightDispatcher.dispatchEvent(Unknown Source)
at java.awt.Container.dispatchEventImpl(Unknown Source)
at java.awt.Window.dispatchEventImpl(Unknown Source)
at java.awt.Component.dispatchEvent(Unknown Source)
at java.awt.EventQueue.dispatchEventImpl(Unknown Source)
at java.awt.EventQueue.access$000(Unknown Source)
at java.awt.EventQueue$1.run(Unknown Source)
at java.awt.EventQueue$1.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.AccessControlContext$1.doIntersectionPrivilege(Unknown Source)
at java.security.AccessControlContext$1.doIntersectionPrivilege(Unknown Source)
at java.awt.EventQueue$2.run(Unknown Source)
at java.awt.EventQueue$2.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.AccessControlContext$1.doIntersectionPrivilege(Unknown Source)
at java.awt.EventQueue.dispatchEvent(Unknown Source)
at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source)81240560
at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.run(Unknown Source)


推荐答案

显然你的应用程序没有足够的内存来完成操作。因此，您需要为虚拟机指定内存标志。您可以尝试以下方法：

Apparently your application doen't have enough memory for complete the operation. So you need to specify memory flags to your virtual machine. You can try the following:

 java -Xms256m -Xmx512m YourApp

其中：


  • 程序在启动时分配的最小内存（在示例256 MB）

  • 如果需要更多（在示例中为512 MB），程序分配的Xmx最大内存

这篇关于在java中使用大字符串时StringBuilder内存不足错误的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！

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