Frequently Asked Questions (FAQ)
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I'm having problems building with Xcode.
See Debugging Build Problems.
How do I fix "undefined symbol" errors when building?
See Required Link Settings.
I'm having problems using j2objc on the command-line.
The fastest way to come up with a command-line for j2objc is to start with javac, specifying the
classpath (optional), sourcepath (optional), output directory, and list of source files. Once that
compiles successfully, substitute "j2objc" for "javac", and add any j2objc-specific flags. The
reason this works is that j2objc uses a Java compiler as it's front-end, and so uses the same
arguments as the compiler. Remember: if it doesn't compile, it can't be translated!
How is garbage collection handled?
See Memory Management. We continue to refine generated code to improve how
memory is managed, using Xcode's leak detection and profiling tools. We encourage projects using
J2ObjC to also monitor performance and leak detection (as all iOS projects should), and to report
any issues found.
How can the translated code size be reduced? What can speed up translation?
See Dead Code Elimination.
How does j2objc handle imports inside of .java files?
j2objc uses the javac compiler as its front-end, so all imports are read as any
Java compiler would do. To specify where to find imported classes, use the same -classpath and
-sourcepath options you would use with javac. When generating Objective-C files, external class
references are gathered, and #import directives are added to either the generated header (.h) or
implementation (.m) files as appropriate.
Why are some of the minimum and maximum values for numeric types different from the Java specification?
These values are different from what Java returns because they are outside what the Objective-C
compiler will accept as valid. We instead use the minimum and maximum values defined in
/usr/include/values.h.
Except as otherwise noted, the content of this page is licensed under the Creative Commons Attribution 4.0 License, and code samples are licensed under the Apache 2.0 License. For details, see the Google Developers Site Policies. Java is a registered trademark of Oracle and/or its affiliates.
Last updated 2024-07-10 UTC.
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