summaryrefslogtreecommitdiff
path: root/Examples/java/constants
diff options
context:
space:
mode:
Diffstat (limited to 'Examples/java/constants')
-rw-r--r--Examples/java/constants/Makefile18
-rw-r--r--Examples/java/constants/example.i30
-rw-r--r--Examples/java/constants/index.html52
-rw-r--r--Examples/java/constants/runme.java44
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)");
+ }
+ }
+}