diff options
Diffstat (limited to 'Examples/java/constants')
-rw-r--r-- | Examples/java/constants/Makefile | 18 | ||||
-rw-r--r-- | Examples/java/constants/example.i | 30 | ||||
-rw-r--r-- | Examples/java/constants/index.html | 52 | ||||
-rw-r--r-- | Examples/java/constants/runme.java | 44 |
4 files changed, 144 insertions, 0 deletions
diff --git a/Examples/java/constants/Makefile b/Examples/java/constants/Makefile new file mode 100644 index 0000000..2b3d35c --- /dev/null +++ b/Examples/java/constants/Makefile @@ -0,0 +1,18 @@ +TOP = ../.. +SWIG = $(TOP)/../preinst-swig +CXXSRCS = +TARGET = example +INTERFACE = example.i +SWIGOPT = + +all:: java + +java:: + $(MAKE) -f $(TOP)/Makefile CXXSRCS='$(CXXSRCS)' SWIG='$(SWIG)' \ + SWIGOPT='$(SWIGOPT)' TARGET='$(TARGET)' INTERFACE='$(INTERFACE)' java_cpp + javac *.java + +clean:: + $(MAKE) -f $(TOP)/Makefile java_clean + +check: all diff --git a/Examples/java/constants/example.i b/Examples/java/constants/example.i new file mode 100644 index 0000000..76665fc --- /dev/null +++ b/Examples/java/constants/example.i @@ -0,0 +1,30 @@ +/* File : example.i */ +%module example + +/* Force the generated Java code to use the C constant values rather than making a JNI call */ +%javaconst(1); + +/* A few preprocessor macros */ + +#define ICONST 42 +#define FCONST 2.1828 +#define CCONST 'x' +#define CCONST2 '\n' +#define SCONST "Hello World" +#define SCONST2 "\"Hello World\"" + +/* This should work just fine */ +#define EXPR ICONST + 3*(FCONST) + +/* This shouldn't do anything */ +#define EXTERN extern + +/* Neither should this (BAR isn't defined) */ +#define FOO (ICONST + BAR) + +/* The following directives also produce constants */ + +%constant int iconst = 37; +%constant double fconst = 3.14; + + diff --git a/Examples/java/constants/index.html b/Examples/java/constants/index.html new file mode 100644 index 0000000..9f1e95a --- /dev/null +++ b/Examples/java/constants/index.html @@ -0,0 +1,52 @@ +<html> +<head> +<title>SWIG:Examples:java:constants</title> +</head> + +<body bgcolor="#ffffff"> + +<tt>SWIG/Examples/java/constants/</tt> +<hr> + +<H2>Wrapping C Constants</H2> + +<p> +When SWIG encounters C preprocessor macros and C declarations that look like constants, +it creates Java constant with an identical value. Click <a href="example.i">here</a> +to see a SWIG interface with some constant declarations in it. + + +<h2>Accessing Constants from Java</h2> +Click <a href="../../../Doc/Manual/Java.html#constants">here</a> for the section on constants in the SWIG and Java documentation. +<p> + +Click <a href="runme.java">here</a> to see a Java program that prints out the values +of the constants contained in the above file.</p> +<h2>Key points</h2> +<ul> +<li>The values of preprocessor macros are converted into Java constants. +<li>Types are inferred by syntax (e.g., "3" is an integer and "3.5" is a float). +<li>Character constants such as 'x' are converted into Java strings. +<li>C string literals such as "Hello World" are converted into Java strings. +<li>Macros that are not fully defined are simply ignored. For example: +<blockquote> +<pre> +#define EXTERN extern +</pre> +</blockquote> +is ignored because SWIG has no idea what type of variable this would be. + +<p> +<li>Expressions are allowed provided that all of their components are defined. Otherwise, the constant is ignored. + +<li>Certain C declarations involving 'const' are also turned into Java constants. +<li>The constants that appear in a SWIG interface file do not have to appear in any sort +of matching C source file since the creation of a constant does not require linkage +to a stored value (i.e., a value held in a C global variable or memory location). +</ul> + +<hr> + + +</body> +</html> diff --git a/Examples/java/constants/runme.java b/Examples/java/constants/runme.java new file mode 100644 index 0000000..2c67d86 --- /dev/null +++ b/Examples/java/constants/runme.java @@ -0,0 +1,44 @@ +import java.lang.reflect.*; + +public class runme { + static { + try { + System.loadLibrary("example"); + } catch (UnsatisfiedLinkError e) { + System.err.println("Native code library failed to load. See the chapter on Dynamic Linking Problems in the SWIG Java documentation for help.\n" + e); + System.exit(1); + } + } + + public static void main(String argv[]) + { + System.out.println("ICONST = " + example.ICONST + " (should be 42)"); + System.out.println("FCONST = " + example.FCONST + " (should be 2.1828)"); + System.out.println("CCONST = " + example.CCONST + " (should be 'x')"); + System.out.println("CCONST2 = " + example.CCONST2 + " (this should be on a new line)"); + System.out.println("SCONST = " + example.SCONST + " (should be 'Hello World')"); + System.out.println("SCONST2 = " + example.SCONST2 + " (should be '\"Hello World\"')"); + System.out.println("EXPR = " + example.EXPR + " (should be 48.5484)"); + System.out.println("iconst = " + example.iconst + " (should be 37)"); + System.out.println("fconst = " + example.fconst + " (should be 3.14)"); + +// Use reflection to check if these variables are defined: + try + { + System.out.println("EXTERN = " + example.class.getField("EXTERN") + " (Arg! This shouldn't print anything)"); + } + catch (NoSuchFieldException e) + { + System.out.println("EXTERN isn't defined (good)"); + } + + try + { + System.out.println("FOO = " + example.class.getField("FOO") + " (Arg! This shouldn't print anything)"); + } + catch (NoSuchFieldException e) + { + System.out.println("FOO isn't defined (good)"); + } + } +} |