Added format and optimize imports entry point.

Fixes #92

MOE_MIGRATED_REVID=171984272

Author: sormuras

core/src/main/java/com/google/googlejavaformat/java/Formatter.java

@@ -193,6 +193,8 @@ public void formatSource(CharSource input, CharSink output)
   /**
    * Format an input string (a Java compilation unit) into an output string.
    *
+   * <p>Leaves import statements untouched.
+   *
    * @param input the input string
    * @return the output string
    * @throws FormatterException if the input string cannot be parsed
@@ -201,6 +203,24 @@ public String formatSource(String input) throws FormatterException {
     return formatSource(input, ImmutableList.of(Range.closedOpen(0, input.length())));
   }
 
+  /**
+   * Formats an input string (a Java compilation unit) and fixes imports.
+   *
+   * <p>Fixing imports includes ordering, spacing, and removal of unused import statements.
+   *
+   * @param input the input string
+   * @return the output string
+   * @throws FormatterException if the input string cannot be parsed
+   * @see <a
+   *     href="https://google.github.io/styleguide/javaguide.html#s3.3.3-import-ordering-and-spacing">
+   *     Google Java Style Guide - 3.3.3 Import ordering and spacing</a>
+   */
+  public String formatSourceAndFixImports(String input) throws FormatterException {
+    input = ImportOrderer.reorderImports(input);
+    input = RemoveUnusedImports.removeUnusedImports(input);
+    return formatSource(input);
+  }
+
   /**
    * Format an input string (a Java compilation unit), for only the specified character ranges.
    * These ranges are extended as necessary (e.g., to encompass whole lines).

core/src/test/java/com/google/googlejavaformat/java/FormatterTest.java

@@ -248,6 +248,25 @@ public void importsNotReorderedByDefault() throws FormatterException {
     assertThat(output).isEqualTo(expect);
   }
 
+  @Test
+  public void importsFixedIfRequested() throws FormatterException {
+    String input =
+        "package com.google.example;\n"
+            + UNORDERED_IMPORTS
+            + "\npublic class ExampleTest {\n"
+            + "  @Nullable List<?> xs;\n"
+            + "}\n";
+    String output = new Formatter().formatSourceAndFixImports(input);
+    String expect =
+        "package com.google.example;\n\n"
+            + "import java.util.List;\n"
+            + "import javax.annotations.Nullable;\n\n"
+            + "public class ExampleTest {\n"
+            + "  @Nullable List<?> xs;\n"
+            + "}\n";
+    assertThat(output).isEqualTo(expect);
+  }
+
   @Test
   public void importOrderingWithoutFormatting() throws IOException, UsageException {
     importOrdering(

core/src/test/java/com/google/googlejavaformat/java/MainTest.java

@@ -201,6 +201,47 @@ public void imports() throws Exception {
     assertThat(out.toString()).isEqualTo(joiner.join(expected));
   }
 
+  @Test
+  public void optimizeImportsDoesNotLeaveEmptyLines() throws Exception {
+    String[] input = {
+      "package abc;",
+      "",
+      "import java.util.LinkedList;",
+      "import java.util.List;",
+      "import java.util.ArrayList;",
+      "",
+      "import static java.nio.charset.StandardCharsets.UTF_8;",
+      "",
+      "import java.util.EnumSet;",
+      "",
+      "class Test ",
+      "extends ArrayList {",
+      "}"
+    };
+    String[] expected = {
+      "package abc;", //
+      "",
+      "import java.util.ArrayList;",
+      "",
+      "class Test extends ArrayList {}",
+      ""
+    };
+
+    // pre-check expectation with local formatter instance
+    String optimized = new Formatter().formatSourceAndFixImports(joiner.join(input));
+    assertThat(optimized).isEqualTo(joiner.join(expected));
+
+    InputStream in = new ByteArrayInputStream(joiner.join(input).getBytes(UTF_8));
+    StringWriter out = new StringWriter();
+    Main main =
+        new Main(
+            new PrintWriter(out, true),
+            new PrintWriter(new BufferedWriter(new OutputStreamWriter(System.err, UTF_8)), true),
+            in);
+    assertThat(main.format("-")).isEqualTo(0);
+    assertThat(out.toString()).isEqualTo(joiner.join(expected));
+  }
+
   // test that -lines handling works with import removal
   @Test
   public void importRemovalLines() throws Exception {