organise imports according to Google style

packages/prettier-plugin-java/src/printers/packages-and-modules.js

@@ -10,7 +10,8 @@ const {
   rejectAndJoinSeps,
   displaySemicolon,
   putIntoCurlyBraces,
-  getBlankLinesSeparator
+  getBlankLinesSeparator,
+  sortImports
 } = require("./printer-utils");
 
 class PackagesAndModulesPrettierVisitor {
@@ -22,17 +23,20 @@ class PackagesAndModulesPrettierVisitor {
 
   ordinaryCompilationUnit(ctx) {
     const packageDecl = this.visit(ctx.packageDeclaration);
-    // TODO: Should imports be sorted? Can imports in Java be safely sorted?
-    // TODO2: should the imports be grouped in some manner?
-    const importsDecl = this.mapVisit(ctx.importDeclaration);
+
+    const sortedImportsDecl = sortImports(ctx.importDeclaration);
+    const nonStaticImports = this.mapVisit(sortedImportsDecl.nonStaticImports);
+    const staticImports = this.mapVisit(sortedImportsDecl.staticImports);
+
     const typesDecl = this.mapVisit(ctx.typeDeclaration);
 
     // TODO: utility to add item+line (or multiple lines) but only if an item exists
     return rejectAndConcat([
-      rejectAndJoin(concat([line, line]), [
+      rejectAndJoin(concat([hardline, hardline]), [
         packageDecl,
-        rejectAndJoin(line, importsDecl),
-        rejectAndJoin(concat([line, line]), typesDecl)
+        rejectAndJoin(hardline, staticImports),
+        rejectAndJoin(hardline, nonStaticImports),
+        rejectAndJoin(concat([hardline, hardline]), typesDecl)
       ]),
       line
     ]);

packages/prettier-plugin-java/src/printers/printer-utils.js

@@ -531,6 +531,63 @@ function isStatementEmptyStatement(statement) {
   );
 }
 
+function sortImports(imports) {
+  const staticImports = [];
+  const nonStaticImports = [];
+
+  if (imports !== undefined) {
+    for (let i = 0; i < imports.length; i++) {
+      if (imports[i].children.Static !== undefined) {
+        staticImports.push(imports[i]);
+      } else if (imports[i].children.emptyStatement === undefined) {
+        nonStaticImports.push(imports[i]);
+      }
+    }
+
+    // TODO: Could be optimized as we could expect that the array is already almost sorted
+    staticImports.sort((first, second) =>
+      compareFqn(
+        first.children.packageOrTypeName[0],
+        second.children.packageOrTypeName[0]
+      )
+    );
+    nonStaticImports.sort((first, second) =>
+      compareFqn(
+        first.children.packageOrTypeName[0],
+        second.children.packageOrTypeName[0]
+      )
+    );
+  }
+
+  return {
+    staticImports,
+    nonStaticImports
+  };
+}
+
+function compareFqn(packageOrTypeNameFirst, packageOrTypeNameSecond) {
+  const identifiersFirst = packageOrTypeNameFirst.children.Identifier;
+  const identifiersSecond = packageOrTypeNameSecond.children.Identifier;
+
+  const minParts = Math.min(identifiersFirst.length, identifiersSecond.length);
+  for (let i = 0; i < minParts; i++) {
+    const identifierComparison = identifiersFirst[i].image.localeCompare(
+      identifiersSecond[i].image
+    );
+    if (identifierComparison !== 0) {
+      return identifierComparison;
+    }
+  }
+
+  if (identifiersFirst.length < identifiersSecond.length) {
+    return -1;
+  } else if (identifiersFirst.length > identifiersSecond.length) {
+    return 1;
+  }
+
+  return 0;
+}
+
 module.exports = {
   buildFqn,
   reject,
@@ -556,5 +613,6 @@ module.exports = {
   retrieveNodesToken,
   buildOriginalText,
   getCSTNodeStartEndToken,
-  isStatementEmptyStatement
+  isStatementEmptyStatement,
+  sortImports
 };

packages/prettier-plugin-java/test/unit-test/comments/class/_output.java

@@ -18,6 +18,7 @@
 import static com.google.common.base.Preconditions.checkArgument;
 import static com.google.common.base.Preconditions.checkElementIndex;
 import static com.google.common.base.Preconditions.checkNotNull;
+
 import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtCompatible;
 import com.google.common.annotations.GwtIncompatible;

packages/prettier-plugin-java/test/unit-test/package_and_imports/_input.java

@@ -4,5 +4,12 @@
 import java.utils.*;;;
 import abc.def.Something;
 import abc.def.Another;;;
+import abc.def;
+import static abc.def;
+import  static something.Different;
+import static  java.utils.*;;;
+import static abc.def.Something;
+import static abc.def.Another;;;
+import one.last;;;
 
 public class PackageAndImports {}

packages/prettier-plugin-java/test/unit-test/package_and_imports/_output.java

@@ -1,8 +1,16 @@
 package my.own.pkg;
 
-import something.Different;
-import java.utils.*;
-import abc.def.Something;
+import static abc.def;
+import static abc.def.Another;
+import static abc.def.Something;
+import static java.utils.*;
+import static something.Different;
+
+import abc.def;
 import abc.def.Another;
+import abc.def.Something;
+import java.utils.*;
+import one.last;
+import something.Different;
 
 public class PackageAndImports {}