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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.
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 = "";
}
I then discovered that StringBuilder exists, and I've been trying to use it since, replacing all string operations with it.
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.
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.
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);
}
}
Here is the error:
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$1.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
I think this is what a stack trace is:
java.lang.Exception: Stack trace
at java.lang.Thread.dumpStack(Unknown Source)
at frontend.fillOutputPane(frontend.java:385)
at page.concatPlates(page.java:105)
at backend.setPlate(backend.java:77)
at backend.fill(backend.java:257)
at frontend$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)
537
Here because of parameter as int the maximum capacity that a StringBuilder Class can is reach will be 2147483647 .
The length is an int so it should hold up to 2GChar (4GB) assuming you have the memory. You are going to use "only" 600MB (300 million @ 2 bytes per character).
The maximum capacity for this implementation is Int32. MaxValue. However, this value is implementation-specific and might be different in other or later implementations. You can explicitly set the maximum capacity of a StringBuilder object by calling the StringBuilder(Int32, Int32) constructor.
I think we should go with StringBuilder append approach. Reason being : The String concatenate will create a new string object each time (As String is immutable object) , so it will create 3 objects. With String builder only one object will created[StringBuilder is mutable] and the further string gets appended to it.
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
Where:
133
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