Java“常量字符串太长”编译错误。 仅在使用 Ant 时发生，在使用 Eclipse 时不会发生

Question

I have a few really long strings in one class for initializing user information. When I compile in Eclipse, I don't get any errors or warnings, and the resulting .jar runs fine.

Recently, I decided to create an ant build file to use. Whenever I compile the same class with ant, I get the "constant string too long" compile error. I've tried a number of ways to set the java compiler executable in ant to make sure that I'm using the exact same version as in Eclipse.

I'd rather figure out how to get the same successful compile I get in Eclipse in Ant than try to rework the code to dynamically concatenate the strings.

Answer 1

Someone is trying to send you a message :-) In the time you've spend fiddling with compiler versions you could have loaded the data from a text file - which is probably where it belongs.

Check out:

• java.util.Properties
• Apache Commons FileUtils.readFileToString()

Answer 2

I found I could use the apache commons lang StringUtils.join( Object[] ) method to solve this.

public static final String CONSTANT = org.apache.commons.lang.StringUtils.join( new String[] {
  "This string is long", 
  "really long...", 
  "really, really LONG!!!" 
} );

Answer 3

Nothing of above worked for me. I have created one text file with name test.txt and read this text file using below code

String content = new String(Files.readAllBytes(Paths.get("test.txt")));

Answer 4

The length of a string constant in a class file is limited to 2^16 bytes in UTF-8 encoding, this should not be dependent on the compiler used. Perhaps you are using a different character set in your ant file than in eclipse, so that some characters need more bytes than before. Please check the encoding attribute of your javac task.

Answer 5

A workaround is to chunk your string using new String() (yikes) or StringBuilder , eg

String CONSTANT = new String("first chunk") 
                + new String("second chunk") + ... 
                + new String("...");

Or

String CONSTANT = new StringBuilder("first chunk")
                .append("second chunk")
                .append("...")
                .toString();

These can be viable options if you're producing this string eg from a code generator. The workaround documented in this answer where string literals are concatenated no longer works with Java 11

Answer 6

  String theString2 = IOUtils.toString(new FileInputStream(new     
  File(rootDir + "/properties/filename.text")), "UTF-8");

Answer 7

Another trick, if I'm determined to put a long string in the source, is to avoid the compiler detecting it as a constant expression.

String dummyVar = "";
String longString = dummyVar +
    "This string is long\n" + 
    "really long...\n" + 
    "really, really LONG!!!";

This worked for a while, but if you keep going too far the next problem is a stack overflow in the compiler. This describes the same problem and, if you're still determined, how to increase your stack - the problem seems to be the sheer size of the method now. Again this wasn't a problem in Eclipse.

Answer 8

Did you try this ? Never tried it myself, but here is the relevant section:

Using the ant javac adapter The Eclipse compiler can be used inside an Ant script using the javac adapter. In order to use the Eclipse compiler, you simply need to define the build.compiler property in your script. Here is a small example.

 <?xml version="1.0" encoding="UTF-8"?>
 <project name="compile" default="main" basedir="../.">

<property name="build.compiler" value="org.eclipse.jdt.core.JDTCompilerAdapter"/>

<property name="root" value="${basedir}/src"/>

<property name="destdir" value="d:/temp/bin" />

<target name="main">
    <javac srcdir="${root}" destdir="${destdir}" debug="on" nowarn="on" extdirs="d:/extdirs" source="1.4">
        <classpath>
          <pathelement location="${basedir}/../org.eclipse.jdt.core/bin"/>
        </classpath>
    </javac>        
</target>
</project>

I would really consider making your classes standards compatible. I believe the official limit is 65535, and the fact that Eclipse is more lenient is something that could change on you at the most inconvenient of times, and either way constantly having to get the project compiled with Eclipse can really start to limit you in too many ways.

Answer 9

将您的字符串添加到 values/strings.xml 中，而不是调用 getResources.getString(R.string.yourstring)

Answer 10

I was able to resolve this issue in a similar way like Lukas Eder.

String testXML = "REALLY LONG STRING...............................";
       textXML += "SECOND PART OF REALLY LONG STRING..........";
       textXML += "THIRD PART OF REALLY LONG STRING............";

Just split it up and add it together;

Answer 11

permanent solution would be for this is getting long string from file specially when you are writing test case in spring projects . the below one worked for me

File resource = new ClassPathResource(
      "data/employees.dat").getFile();
    String employees = new String(
      Files.readAllBytes(resource.toPath()));

Answer 12

你可以试试这个

public static final String CONSTANT = new StringBuilder("Your really long string").toString();