EmptyIf
Empty statement after if

Category
Severity
ERROR
Maturity

Alternate names: empty

The problem

An if statement contains an empty statement as the then clause. A semicolon may have been inserted by accident.

Suppression

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


Positive examples

EmptyIfStatementPositiveCases.java

/*
 * Copyright 2011 Google Inc. All Rights Reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.google.errorprone.bugpatterns.testdata;

/**
 * Positive test cases for the empty if statement check.
 *
 * @author eaftan@google.com (Eddie Aftandilian)
 */
public class EmptyIfStatementPositiveCases {

  public static void positiveCase1() {
    int i = 10;
    // BUG: Diagnostic contains: if (i == 10) {
    if (i == 10); {
      i++;
    }
  }

  public static void positiveCase2() {
    int i = 10;
    // BUG: Diagnostic contains: if (i == 10)
    if (i == 10);
    i++;
    System.out.println("foo");
  }

  public static void positiveCase3() {
    int i = 10;
    if (i == 10)
      // BUG: Diagnostic contains: remove this line
      ;
    i++;
    System.out.println("foo");
  }

  public static void positiveCase4() {
    int i = 10;
    // BUG: Diagnostic contains: remove this line
    if (i == 10)            ;
  }
  
  public static void positiveCase5() {
    int i = 10;
    if (i == 10)
      // BUG: Diagnostic contains: remove this line
      ;
    {
      System.out.println("foo");
    }
  }
}

Negative examples

EmptyIfStatementNegativeCases.java

/*
 * Copyright 2011 Google Inc. All Rights Reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.google.errorprone.bugpatterns.testdata;
/** @author eaftan@google.com (Eddie Aftandilian) */
public class EmptyIfStatementNegativeCases {

  // just a normal use of if
  public static void negativeCase1() {
    int i = 10;
    if (i == 10) {
      System.out.println("foo");
    }
    i++;
  }

  // empty then part but nonempty else
  public static void negativeCase2() {
    int i = 0;
    if (i == 10) ;
    else System.out.println("not 10");
  }

  // multipart if with non-empty else
  public static void negativeCase3() {
    int i = 0;
    if (i == 10) ;
    else if (i == 11) ;
    else if (i == 12) ;
    else System.out.println("not 10, 11, or 12");
  }
}