StringBuilderInitWithChar
StringBuilder does not have a char constructor; this invokes the int constructor.

Category
JDK
Severity
ERROR
Maturity

The problem

StringBuilder does not have a char constructor, so instead this code creates a StringBuilder with initial size equal to the code point of the specified char.

Suppression

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


Positive examples

StringBuilderInitWithCharPositiveCases.java

/*
 * Copyright 2014 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 lowasser@google.com (Louis Wasserman)
 */
public class StringBuilderInitWithCharPositiveCases {
  {
    // BUG: Diagnostic contains: new StringBuilder("a")
    new StringBuilder('a');
    // BUG: Diagnostic contains: new StringBuilder("\"")
    new StringBuilder('"');
    char c = 'c';
    // BUG: Diagnostic contains: new StringBuilder().append(c)
    new StringBuilder(c);
  }
}

Negative examples

StringBuilderInitWithCharNegativeCases.java

/*
 * Copyright 2014 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 lowasser@google.com (Louis Wasserman)
 */
public class StringBuilderInitWithCharNegativeCases {
  {
    new StringBuilder("a");
    new StringBuilder(5);
    new StringBuilder();
  }
}