Code cleanup (#2282)

* Simplify `if` condition in JsonReader.peekNumber()

* Remove `if` to simplify a `return` in Excluder.excludeClassChecks()

* Remove redundant variable in Gson.fromJson()

* equal condition replace by `Objects.equals()` in $Gson$Types.equal()

* equal condition replace by `Objects.equals()` in LinkedTreeMap.equal()

* Replace `switch` with `if` in UtcDateTypeAdapter.read()

* Remove redundant `throws` clause in GraphAdapterBuilder.read()

* Remove redundant `throws` clause in JsonTreeReader.UNREADABLE_READER

* Remove redundant `throws` clause in JsonTreeWriter.UNREADABLE_READER

* Remove unnecessary `.initCause()` call

* Remove redundant cast in TreeTypeAdapter.GsonContextImpl.deserialize

* Replace `StringBuilder` with `String`

* Fix the import and restore the `switch`

* Fix the import

* Add the `util.Objects` import

* Fix indentation

* Add a comment to clarify the condition

* Fix indentation

* Fix imports

* Fix indentation

* Fix indentation

* Fix indentation

extras/src/main/java/com/google/gson/graph/GraphAdapterBuilder.java

@@ -298,7 +298,7 @@ public final class GraphAdapterBuilder {
     }
 
     @SuppressWarnings("unchecked")
-    void read(Graph graph) throws IOException {
+    void read(Graph graph) {
       if (graph.nextCreate != null) {
         throw new IllegalStateException("Unexpected recursive call to read() for " + id);
       }

extras/src/main/java/com/google/gson/typeadapters/UtcDateTypeAdapter.java

@@ -24,10 +24,10 @@ import java.util.Date;
 import java.util.GregorianCalendar;
 import java.util.Locale;
 import java.util.TimeZone;
-
 import com.google.gson.JsonParseException;
 import com.google.gson.TypeAdapter;
 import com.google.gson.stream.JsonReader;
+import com.google.gson.stream.JsonToken;
 import com.google.gson.stream.JsonWriter;
 
 public final class UtcDateTypeAdapter extends TypeAdapter<Date> {

gson/src/main/java/com/google/gson/Gson.java

@@ -843,9 +843,7 @@ public final class Gson {
     } catch (IOException e) {
       throw new JsonIOException(e);
     } catch (AssertionError e) {
-      AssertionError error = new AssertionError("AssertionError (GSON " + GsonBuildConfig.VERSION + "): " + e.getMessage());
-      error.initCause(e);
-      throw error;
+      throw new AssertionError("AssertionError (GSON " + GsonBuildConfig.VERSION + "): " + e.getMessage(), e);
     } finally {
       writer.setLenient(oldLenient);
       writer.setHtmlSafe(oldHtmlSafe);
@@ -948,9 +946,7 @@ public final class Gson {
     } catch (IOException e) {
       throw new JsonIOException(e);
     } catch (AssertionError e) {
-      AssertionError error = new AssertionError("AssertionError (GSON " + GsonBuildConfig.VERSION + "): " + e.getMessage());
-      error.initCause(e);
-      throw error;
+      throw new AssertionError("AssertionError (GSON " + GsonBuildConfig.VERSION + "): " + e.getMessage(), e);
     } finally {
       writer.setLenient(oldLenient);
       writer.setHtmlSafe(oldHtmlSafe);
@@ -1228,8 +1224,7 @@ public final class Gson {
       reader.peek();
       isEmpty = false;
       TypeAdapter<T> typeAdapter = getAdapter(typeOfT);
-      T object = typeAdapter.read(reader);
-      return object;
+      return typeAdapter.read(reader);
     } catch (EOFException e) {
       /*
        * For compatibility with JSON 1.5 and earlier, we return null for empty
@@ -1245,9 +1240,7 @@ public final class Gson {
       // TODO(inder): Figure out whether it is indeed right to rethrow this as JsonSyntaxException
       throw new JsonSyntaxException(e);
     } catch (AssertionError e) {
-      AssertionError error = new AssertionError("AssertionError (GSON " + GsonBuildConfig.VERSION + "): " + e.getMessage());
-      error.initCause(e);
-      throw error;
+      throw new AssertionError("AssertionError (GSON " + GsonBuildConfig.VERSION + "): " + e.getMessage(), e);
     } finally {
       reader.setLenient(oldLenient);
     }
@@ -1381,11 +1374,9 @@ public final class Gson {
 
   @Override
   public String toString() {
-    return new StringBuilder("{serializeNulls:")
-        .append(serializeNulls)
-        .append(",factories:").append(factories)
-        .append(",instanceCreators:").append(constructorConstructor)
-        .append("}")
-        .toString();
+    return "{serializeNulls:" + serializeNulls
+        + ",factories:" + factories
+        + ",instanceCreators:" + constructorConstructor
+        + "}";
   }
 }

gson/src/main/java/com/google/gson/internal/$Gson$Types.java

@@ -34,6 +34,7 @@ import java.util.HashMap;
 import java.util.Map;
 import java.util.NoSuchElementException;
 import java.util.Properties;
+import java.util.Objects;
 
 /**
  * Static methods for working with types.
@@ -167,7 +168,7 @@ public final class $Gson$Types {
   }
 
   private static boolean equal(Object a, Object b) {
-    return a == b || (a != null && a.equals(b));
+    return Objects.equals(a, b);
   }
 
   /**

gson/src/main/java/com/google/gson/internal/Excluder.java

@@ -198,11 +198,7 @@ public final class Excluder implements TypeAdapterFactory, Cloneable {
           return true;
       }
 
-      if (isAnonymousOrNonStaticLocal(clazz)) {
-          return true;
-      }
-
-      return false;
+      return isAnonymousOrNonStaticLocal(clazz);
   }
 
   public boolean excludeClass(Class<?> clazz, boolean serialize) {

gson/src/main/java/com/google/gson/internal/LinkedTreeMap.java

@@ -30,6 +30,7 @@ import java.util.Iterator;
 import java.util.LinkedHashMap;
 import java.util.NoSuchElementException;
 import java.util.Set;
+import java.util.Objects;
 
 /**
  * A map of comparable keys to values. Unlike {@code TreeMap}, this class uses
@@ -227,7 +228,7 @@ public final class LinkedTreeMap<K, V> extends AbstractMap<K, V> implements Seri
   }
 
   private boolean equal(Object a, Object b) {
-    return a == b || (a != null && a.equals(b));
+    return Objects.equals(a, b);
   }
 
   /**

gson/src/main/java/com/google/gson/internal/bind/JsonTreeReader.java

@@ -38,10 +38,10 @@ import java.util.Map;
  */
 public final class JsonTreeReader extends JsonReader {
   private static final Reader UNREADABLE_READER = new Reader() {
-    @Override public int read(char[] buffer, int offset, int count) throws IOException {
+    @Override public int read(char[] buffer, int offset, int count) {
       throw new AssertionError();
     }
-    @Override public void close() throws IOException {
+    @Override public void close() {
       throw new AssertionError();
     }
   };

gson/src/main/java/com/google/gson/internal/bind/JsonTreeWriter.java

@@ -36,10 +36,10 @@ public final class JsonTreeWriter extends JsonWriter {
     @Override public void write(char[] buffer, int offset, int counter) {
       throw new AssertionError();
     }
-    @Override public void flush() throws IOException {
+    @Override public void flush() {
       throw new AssertionError();
     }
-    @Override public void close() throws IOException {
+    @Override public void close() {
       throw new AssertionError();
     }
   };

gson/src/main/java/com/google/gson/internal/bind/TreeTypeAdapter.java

@@ -176,7 +176,7 @@ public final class TreeTypeAdapter<T> extends SerializationDelegatingTypeAdapter
     }
     @SuppressWarnings("unchecked")
     @Override public <R> R deserialize(JsonElement json, Type typeOfT) throws JsonParseException {
-      return (R) gson.fromJson(json, typeOfT);
+      return gson.fromJson(json, typeOfT);
     }
   }
 }

gson/src/main/java/com/google/gson/stream/JsonReader.java

@@ -737,7 +737,9 @@ public class JsonReader implements Closeable {
     }
 
     // We've read a complete number. Decide if it's a PEEKED_LONG or a PEEKED_NUMBER.
-    if (last == NUMBER_CHAR_DIGIT && fitsInLong && (value != Long.MIN_VALUE || negative) && (value!=0 || false==negative)) {
+    // Don't store -0 as long; user might want to read it as double -0.0
+    // Don't try to convert Long.MIN_VALUE to positive long; it would overflow MAX_VALUE
+    if (last == NUMBER_CHAR_DIGIT && fitsInLong && (value != Long.MIN_VALUE || negative) && (value!=0 || !negative)) {
       peekedLong = negative ? value : -value;
       pos += i;
       return peeked = PEEKED_LONG;

metrics/src/main/java/com/google/gson/metrics/BagOfPrimitives.java

@@ -43,14 +43,12 @@ public class BagOfPrimitives {
   }
 
   public String getExpectedJson() {
-    StringBuilder sb = new StringBuilder();
-    sb.append("{");
-    sb.append("\"longValue\":").append(longValue).append(",");
-    sb.append("\"intValue\":").append(intValue).append(",");
-    sb.append("\"booleanValue\":").append(booleanValue).append(",");
-    sb.append("\"stringValue\":\"").append(stringValue).append("\"");
-    sb.append("}");
-    return sb.toString();
+    return "{"
+        + "\"longValue\":" + longValue + ","
+        + "\"intValue\":" + intValue + ","
+        + "\"booleanValue\":" + booleanValue + ","
+        + "\"stringValue\":\"" + stringValue + "\""
+        + "}";
   }
 
   @Override