Chromium Docs - Accessing C++ Switches In Java (original) (raw)
Introduction
Accessing C++ switches in Java is implemented via a Python script which analyzes the C++ switches file and generates the corresponding Java class, based on a template file. The template file must be specified in the GN target.
Usage
- Create a template file (ex.
FooSwitches.java.tmpl). Change “Copyright 2020” to be whatever the year is at the time of writing (as you would for any other file).
// Copyright 2020 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
package org.chromium.foo;
// Be sure to escape any curly braces in your template by doubling as
// follows.
/**
- Contains command line switches that are specific to the foo project.
*/
public final class FooSwitches {{
{NATIVE_STRINGS}
// Prevents instantiation.
private FooSwitches() {{}}
}}
- Add a new build target and add it to the
srcjar_depsof anandroid_librarytarget:
if (is_android) {
import("//build/config/android/rules.gni")
}
if (is_android) {
java_cpp_strings("java_switches_srcjar") {External code should depend on ":foo_java" instead.
visibility = [ ":*" ]
sources = [
"//base/android/foo_switches.cc",
]
template = "//base/android/java_templates/FooSwitches.java.tmpl"
}
If there's already an android_library target, you can add
java_switches_srcjar to that target's srcjar_deps. Otherwise, the best
practice is to create a new android_library just for this target.
android_library("foo_java") {
srcjar_deps = [ ":java_switches_srcjar" ]
}
}
3. The generated file out/Default/gen/.../org/chromium/foo/FooSwitches.java would contain:
// Copyright $YEAR The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
package org.chromium.foo;
/**
- Contains command line switches that are specific to the foo project.
*/
public final class FooSwitches {
// ...snip...
// This following string constants were inserted by
// java_cpp_strings.py
// From
// ../../base/android/foo_switches.cc
// Into
// ../../base/android/java_templates/FooSwitches.java.tmpl
// Documentation for the C++ switch is copied here.
public static final String SOME_SWITCH = "some-switch";
// ...snip...
// Prevents instantiation.
private FooSwitches() {}
}