IdentityConversion

WARNING

Simplification

View source code on GitHub

Summary

Avoid or clarify identity conversions

Suppression

Suppress false positives by adding the suppression annotation @SuppressWarnings("IdentityConversion") to the enclosing element.

Disable this pattern completely by adding -Xep:IdentityConversion:OFF as compiler argument. Learn more.

Samples

Replacement

Shows the difference in example code before and after the bug pattern is applied.

 import static com.google.errorprone.matchers.Matchers.staticMethod;
 import static org.mockito.Mockito.when;
 
 import com.google.common.collect.ImmutableCollection;
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableSet;
 import com.google.errorprone.matchers.Matcher;
 import com.google.errorprone.matchers.Matchers;
 import java.util.ArrayList;
 import java.util.Collection;
 import org.reactivestreams.Publisher;
 import reactor.adapter.rxjava.RxJava2Adapter;
 import reactor.core.publisher.Flux;
 import reactor.core.publisher.Mono;
 
 public final class A {
   public void m() {
-    ImmutableSet<Object> set1 = ImmutableSet.copyOf(ImmutableSet.of());
+    ImmutableSet<Object> set1 = ImmutableSet.of();
     ImmutableSet<Object> set2 = ImmutableSet.copyOf(ImmutableList.of());
 
-    ImmutableCollection<Integer> list1 = ImmutableList.copyOf(ImmutableList.of(1));
+    ImmutableCollection<Integer> list1 = ImmutableList.of(1);
     ImmutableCollection<Integer> list2 = ImmutableList.copyOf(new ArrayList<>(ImmutableList.of(1)));
 
-    Collection<Integer> c1 = ImmutableSet.copyOf(ImmutableSet.of(1));
+    Collection<Integer> c1 = ImmutableSet.of(1);
     Collection<Integer> c2 = ImmutableList.copyOf(new ArrayList<>(ImmutableList.of(1)));
 
-    Flux<Integer> f1 = Flux.just(1).flatMap(e -> RxJava2Adapter.fluxToFlowable(Flux.just(2)));
-    Flux<Integer> f2 = Flux.concat(Flux.just(3));
-    Publisher<Integer> f3 = Flux.firstWithSignal(Flux.just(4));
-    Publisher<Integer> f4 = Flux.from(Flux.just(5));
-    Publisher<Integer> f5 = Flux.merge(Flux.just(6));
+    Flux<Integer> f1 = Flux.just(1).flatMap(e -> Flux.just(2));
+    Flux<Integer> f2 = Flux.just(3);
+    Publisher<Integer> f3 = Flux.just(4);
+    Publisher<Integer> f4 = Flux.just(5);
+    Publisher<Integer> f5 = Flux.just(6);
 
-    Mono<Integer> m1 = Mono.from(Mono.just(7));
-    Publisher<Integer> m2 = Mono.fromDirect(Mono.just(8));
+    Mono<Integer> m1 = Mono.just(7);
+    Publisher<Integer> m2 = Mono.just(8);
 
-    bar(Flux.concat(Flux.just(9)));
-    bar(Mono.from(Mono.just(10)));
+    bar(Flux.just(9));
+    bar(Mono.just(10));
 
     Object o1 = ImmutableSet.copyOf(ImmutableList.of());
-    Object o2 = ImmutableSet.copyOf(ImmutableSet.of());
+    Object o2 = ImmutableSet.of();
 
-    Matcher matcher = Matchers.allOf(staticMethod());
+    Matcher matcher = staticMethod();
 
     when("foo".contains("f")).thenAnswer(inv -> ImmutableSet.copyOf(ImmutableList.of(1)));
   }
 
   void bar(Publisher<Integer> publisher) {}
 }
 

 import com.google.common.collect.ImmutableCollection;
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableSet;
 import java.util.ArrayList;
 
 public final class A {
   public void m() {
+    @SuppressWarnings("IdentityConversion")
     ImmutableSet<Object> set1 = ImmutableSet.copyOf(ImmutableSet.of());
     ImmutableSet<Object> set2 = ImmutableSet.copyOf(ImmutableList.of());
 
+    @SuppressWarnings("IdentityConversion")
     ImmutableCollection<Integer> list1 = ImmutableList.copyOf(ImmutableList.of(1));
     ImmutableCollection<Integer> list2 = ImmutableList.copyOf(new ArrayList<>(ImmutableList.of(1)));
   }
 }
 

Identification

Shows code lines which will (not) be flagged by this bug pattern.
A //BUG: Diagnostic contains: comment is placed above any violating line.

import static com.google.errorprone.matchers.Matchers.instanceMethod;
import static com.google.errorprone.matchers.Matchers.staticMethod;

import com.google.common.collect.ImmutableBiMap;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.ImmutableListMultimap;
import com.google.common.collect.ImmutableMap;
import com.google.common.collect.ImmutableMultimap;
import com.google.common.collect.ImmutableMultiset;
import com.google.common.collect.ImmutableRangeMap;
import com.google.common.collect.ImmutableRangeSet;
import com.google.common.collect.ImmutableSet;
import com.google.common.collect.ImmutableSetMultimap;
import com.google.common.collect.ImmutableTable;
import com.google.errorprone.matchers.Matcher;
import com.google.errorprone.matchers.Matchers;
import java.time.Instant;
import java.time.ZonedDateTime;
import reactor.adapter.rxjava.RxJava2Adapter;
import reactor.core.publisher.Flux;
import reactor.core.publisher.Mono;

public final class A {
  public void m() {
    // BUG: Diagnostic contains:
    Boolean b1 = Boolean.valueOf(Boolean.FALSE);
    // BUG: Diagnostic contains:
    Boolean b2 = Boolean.valueOf(false);
    // BUG: Diagnostic contains:
    boolean b3 = Boolean.valueOf(Boolean.FALSE);
    // BUG: Diagnostic contains:
    boolean b4 = Boolean.valueOf(false);

    // BUG: Diagnostic contains:
    Byte byte1 = Byte.valueOf((Byte) Byte.MIN_VALUE);
    // BUG: Diagnostic contains:
    Byte byte2 = Byte.valueOf(Byte.MIN_VALUE);
    // BUG: Diagnostic contains:
    byte byte3 = Byte.valueOf((Byte) Byte.MIN_VALUE);
    // BUG: Diagnostic contains:
    byte byte4 = Byte.valueOf(Byte.MIN_VALUE);

    // BUG: Diagnostic contains:
    Character c1 = Character.valueOf((Character) 'a');
    // BUG: Diagnostic contains:
    Character c2 = Character.valueOf('a');
    // BUG: Diagnostic contains:
    char c3 = Character.valueOf((Character) 'a');
    // BUG: Diagnostic contains:
    char c4 = Character.valueOf('a');

    // BUG: Diagnostic contains:
    Double d1 = Double.valueOf((Double) 0.0);
    // BUG: Diagnostic contains:
    Double d2 = Double.valueOf(0.0);
    // BUG: Diagnostic contains:
    double d3 = Double.valueOf((Double) 0.0);
    // BUG: Diagnostic contains:
    double d4 = Double.valueOf(0.0);

    // BUG: Diagnostic contains:
    Float f1 = Float.valueOf((Float) 0.0F);
    // BUG: Diagnostic contains:
    Float f2 = Float.valueOf(0.0F);
    // BUG: Diagnostic contains:
    float f3 = Float.valueOf((Float) 0.0F);
    // BUG: Diagnostic contains:
    float f4 = Float.valueOf(0.0F);

    // BUG: Diagnostic contains:
    Integer i1 = Integer.valueOf((Integer) 1);
    // BUG: Diagnostic contains:
    Integer i2 = Integer.valueOf(1);
    // BUG: Diagnostic contains:
    int i3 = Integer.valueOf((Integer) 1);
    // BUG: Diagnostic contains:
    int i4 = Integer.valueOf(1);

    // BUG: Diagnostic contains:
    Long l1 = Long.valueOf((Long) 1L);
    // BUG: Diagnostic contains:
    Long l2 = Long.valueOf(1L);
    // BUG: Diagnostic contains:
    long l3 = Long.valueOf((Long) 1L);
    // BUG: Diagnostic contains:
    long l4 = Long.valueOf(1L);

    Long l5 = Long.valueOf((Integer) 1);
    Long l6 = Long.valueOf(1);
    // BUG: Diagnostic contains:
    long l7 = Long.valueOf((Integer) 1);
    // BUG: Diagnostic contains:
    long l8 = Long.valueOf(1);

    // BUG: Diagnostic contains:
    Short s1 = Short.valueOf((Short) Short.MIN_VALUE);
    // BUG: Diagnostic contains:
    Short s2 = Short.valueOf(Short.MIN_VALUE);
    // BUG: Diagnostic contains:
    short s3 = Short.valueOf((Short) Short.MIN_VALUE);
    // BUG: Diagnostic contains:
    short s4 = Short.valueOf(Short.MIN_VALUE);

    // BUG: Diagnostic contains:
    String boolStr = Boolean.valueOf(Boolean.FALSE).toString();
    int boolHash = Boolean.valueOf(false).hashCode();
    // BUG: Diagnostic contains:
    int byteHash = Byte.valueOf((Byte) Byte.MIN_VALUE).hashCode();
    String byteStr = Byte.valueOf(Byte.MIN_VALUE).toString();

    String str1 = String.valueOf(0);
    // BUG: Diagnostic contains:
    String str2 = String.valueOf("1");

    // BUG: Diagnostic contains:
    ImmutableBiMap<Object, Object> o1 = ImmutableBiMap.copyOf(ImmutableBiMap.of());
    // BUG: Diagnostic contains:
    ImmutableList<Object> o2 = ImmutableList.copyOf(ImmutableList.of());
    ImmutableListMultimap<Object, Object> o3 =
        // BUG: Diagnostic contains:
        ImmutableListMultimap.copyOf(ImmutableListMultimap.of());
    // BUG: Diagnostic contains:
    ImmutableMap<Object, Object> o4 = ImmutableMap.copyOf(ImmutableMap.of());
    // BUG: Diagnostic contains:
    ImmutableMultimap<Object, Object> o5 = ImmutableMultimap.copyOf(ImmutableMultimap.of());
    // BUG: Diagnostic contains:
    ImmutableMultiset<Object> o6 = ImmutableMultiset.copyOf(ImmutableMultiset.of());
    // BUG: Diagnostic contains:
    ImmutableRangeMap<String, Object> o7 = ImmutableRangeMap.copyOf(ImmutableRangeMap.of());
    // BUG: Diagnostic contains:
    ImmutableRangeSet<String> o8 = ImmutableRangeSet.copyOf(ImmutableRangeSet.of());
    // BUG: Diagnostic contains:
    ImmutableSet<Object> o9 = ImmutableSet.copyOf(ImmutableSet.of());
    ImmutableSetMultimap<Object, Object> o10 =
        // BUG: Diagnostic contains:
        ImmutableSetMultimap.copyOf(ImmutableSetMultimap.of());
    // BUG: Diagnostic contains:
    ImmutableTable<Object, Object, Object> o11 = ImmutableTable.copyOf(ImmutableTable.of());

    Instant instant1 = Instant.from(ZonedDateTime.now());
    // BUG: Diagnostic contains:
    Instant instant2 = Instant.from(Instant.now());

    // BUG: Diagnostic contains:
    Matcher allOf1 = Matchers.allOf(instanceMethod());
    Matcher allOf2 = Matchers.allOf(instanceMethod(), staticMethod());
    // BUG: Diagnostic contains:
    Matcher anyOf1 = Matchers.anyOf(staticMethod());
    Matcher anyOf2 = Matchers.anyOf(instanceMethod(), staticMethod());

    // BUG: Diagnostic contains:
    Flux<Integer> flux1 = Flux.just(1).flatMap(e -> RxJava2Adapter.fluxToFlowable(Flux.just(2)));

    // BUG: Diagnostic contains:
    Flux<Integer> flux2 = Flux.concat(Flux.just(1));
    // BUG: Diagnostic contains:
    Flux<Integer> flux3 = Flux.firstWithSignal(Flux.just(1));
    // BUG: Diagnostic contains:
    Flux<Integer> flux4 = Flux.from(Flux.just(1));
    // BUG: Diagnostic contains:
    Flux<Integer> flux5 = Flux.merge(Flux.just(1));

    // BUG: Diagnostic contains:
    Mono<Integer> mono1 = Mono.from(Mono.just(1));
    // BUG: Diagnostic contains:
    Mono<Integer> mono2 = Mono.fromDirect(Mono.just(1));
  }
}