DirectReturn

SUGGESTION

Simplification

View source code on GitHub

Summary

Variable assignment is redundant; value can be returned directly

Suppression

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

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

Samples

Replacement

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

 class A {
   String m1() {
     String variable = null;
-    variable = toString();
-    return variable;
+    return toString();
   }
 
   String m2() {
-    String variable = toString();
-    return variable;
+    return toString();
   }
 }
 

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 org.mockito.Mockito.mock;
import static org.mockito.Mockito.spy;

import java.util.function.Supplier;

class A {
  private String field;

  void emptyMethod() {}

  void voidMethod() {
    toString();
    return;
  }

  String directReturnOfParam(String param) {
    return param;
  }

  String assignmentToField() {
    field = toString();
    return field;
  }

  Object redundantAssignmentToParam(String param) {
    // BUG: Diagnostic contains:
    param = toString();
    return param;
  }

  String redundantMockAssignmentToParam(String param) {
    // BUG: Diagnostic contains:
    param = mock();
    return param;
  }

  Object redundantMockWithExplicitTypeAssignmentToParam(String param) {
    // BUG: Diagnostic contains:
    param = mock(String.class);
    return param;
  }

  Object salientMockAssignmentToParam(String param) {
    param = mock();
    return param;
  }

  String redundantAssignmentToLocalVariable() {
    String variable = null;
    // BUG: Diagnostic contains:
    variable = toString();
    return variable;
  }

  String unusedAssignmentToLocalVariable(String param) {
    String variable = null;
    variable = toString();
    return param;
  }

  String redundantVariableDeclaration() {
    // BUG: Diagnostic contains:
    String variable = toString();
    return variable;
  }

  String redundantSpyVariableDeclaration() {
    // BUG: Diagnostic contains:
    String variable = spy();
    return variable;
  }

  Object redundantSpyWithExplicitTypeVariableDeclaration() {
    // BUG: Diagnostic contains:
    String variable = spy(String.class);
    return variable;
  }

  Object salientSpyTypeVariableDeclaration() {
    String variable = spy("name");
    return variable;
  }

  String unusedVariableDeclaration(String param) {
    String variable = toString();
    return param;
  }

  String assignmentToAnnotatedVariable() {
    @SuppressWarnings("HereBeDragons")
    String variable = toString();
    return variable;
  }

  String complexReturnStatement() {
    String variable = toString();
    return variable + toString();
  }

  String assignmentInsideIfClause() {
    String variable = null;
    if (true) {
      variable = toString();
    }
    return variable;
  }

  String redundantAssignmentInsideElseClause() {
    String variable = toString();
    if (true) {
      return variable;
    } else {
      // BUG: Diagnostic contains:
      variable = "foo";
      return variable;
    }
  }

  Supplier<String> redundantAssignmentInsideLambda() {
    return () -> {
      // BUG: Diagnostic contains:
      String variable = toString();
      return variable;
    };
  }

  String redundantAssignmentInsideTryBlock(AutoCloseable closeable) throws Exception {
    try (closeable) {
      // BUG: Diagnostic contains:
      String variable = toString();
      return variable;
    }
  }

  String redundantAssignmentsInsideTryAndFinallyBlocks() {
    String variable = toString();
    try {
      // BUG: Diagnostic contains:
      variable = "foo";
      return variable;
    } finally {
      String variable2 = toString();
      if (true) {
        // BUG: Diagnostic contains:
        String variable3 = toString();
        return variable3;
      }
      return variable2;
    }
  }

  String assignmentUsedInsideFinallyBlock() {
    String variable = toString();
    try {
      variable = "foo";
      return variable;
    } finally {
      String variable2 = toString();
      return variable + variable2;
    }
  }

  String redundantAssignmentToVariableUsedInsideUnexecutedFinallyBlock(AutoCloseable closeable)
      throws Exception {
    String variable = toString();
    try (closeable) {
      if (true) {
        // BUG: Diagnostic contains:
        variable = "foo";
        return variable;
      }
    }
    try {
    } finally {
      return variable;
    }
  }
}