Java, runfiles: move runfiles library sources

Move the Java runfiles library's sources from
//src/tools/runfiles/j/c/g/devtools/build/runfiles:*
to //tools/java/runfiles.

Fixes https://github.com/bazelbuild/bazel/issues/5803

RELNOTES[NEW]: Java, runfiles: the Java runfiles library is now in @bazel_tools//tools/java/runfiles. The old target (@bazel_tools//tools/runfiles:java-runfiles) is deprecated and will be removed in Bazel 0.18.0.

PiperOrigin-RevId: 208191521

1 files changed, 49 insertions, 0 deletions

diff --git a/tools/java/runfiles/Util.java b/tools/java/runfiles/Util.java
new file mode 100644
index 0000000000..73f0b98eeb
--- /dev/null
+++ b/tools/java/runfiles/Util.java
@@ -0,0 +1,49 @@
+// Copyright 2018 The Bazel Authors. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package com.google.devtools.build.runfiles;
+
+/**
+ * Utilities for the other classes in this package.
+ *
+ * <p>These functions are implementations of some basic utilities in the Guava library. We
+ * reimplement these functions instead of depending on Guava, so that the Runfiles library has no
+ * third-party dependencies, thus any Java project can depend on it without the risk of pulling
+ * unwanted or conflicting dependencies (for example if the project already depends on Guava, or
+ * wishes not to depend on it at all).
+ */
+class Util {
+  private Util() {}
+
+  /** Returns true when {@code s} is null or an empty string. */
+  public static boolean isNullOrEmpty(String s) {
+    return s == null || s.isEmpty();
+  }
+
+  /** Throws an {@code IllegalArgumentException} if {@code condition} is false. */
+  public static void checkArgument(boolean condition) {
+    checkArgument(condition, null, null);
+  }
+
+  /** Throws an {@code IllegalArgumentException} if {@code condition} is false. */
+  public static void checkArgument(boolean condition, String error, Object arg1) {
+    if (!condition) {
+      if (isNullOrEmpty(error)) {
+        throw new IllegalArgumentException("argument validation failed");
+      } else {
+        throw new IllegalArgumentException(String.format(error, arg1));
+      }
+    }
+  }
+}