ursinn/DeadByDaylightMC

Programmers should not comment out code as it bloats programs and reduces readability.

Unused code should be deleted and can be retrieved from source control history if required.

Cognitive Complexity is a measure of how hard the control flow of a method is to understand. Methods with high Cognitive Complexity will be difficult to maintain.

See

• Cognitive Complexity

Programmers should not comment out code as it bloats programs and reduces readability.

Unused code should be deleted and can be retrieved from source control history if required.

Connections, streams, files, and other classes that implement the Closeable interface or its super-interface, AutoCloseable, needs to be closed after use. Further, that close call must be made in a finally block otherwise an exception could keep the call from being made. Preferably, when class implements AutoCloseable, resource should be created using "try-with-resources" pattern and will be closed automatically.

Failure to properly close resources will result in a resource leak which could bring first the application and then perhaps the box the application is on to their knees.

Noncompliant Code Example

private void readTheFile() throws IOException {
  Path path = Paths.get(this.fileName);
  BufferedReader reader = Files.newBufferedReader(path, this.charset);
  // ...
  reader.close();  // Noncompliant
  // ...
  Files.lines("input.txt").forEach(System.out::println); // Noncompliant: The stream needs to be closed
}

private void doSomething() {
  OutputStream stream = null;
  try {
    for (String property : propertyList) {
      stream = new FileOutputStream("myfile.txt");  // Noncompliant
      // ...
    }
  } catch (Exception e) {
    // ...
  } finally {
    stream.close();  // Multiple streams were opened. Only the last is closed.
  }
}

Compliant Solution

private void readTheFile(String fileName) throws IOException {
    Path path = Paths.get(fileName);
    try (BufferedReader reader = Files.newBufferedReader(path, StandardCharsets.UTF_8)) {
      reader.readLine();
      // ...
    }
    // ..
    try (Stream<String> input = Files.lines("input.txt"))  {
      input.forEach(System.out::println);
    }
}

private void doSomething() {
  OutputStream stream = null;
  try {
    stream = new FileOutputStream("myfile.txt");
    for (String property : propertyList) {
      // ...
    }
  } catch (Exception e) {
    // ...
  } finally {
    stream.close();
  }
}

Exceptions

Instances of the following classes are ignored by this rule because close has no effect:

• java.io.ByteArrayOutputStream
• java.io.ByteArrayInputStream
• java.io.CharArrayReader
• java.io.CharArrayWriter
• java.io.StringReader
• java.io.StringWriter

Java 7 introduced the try-with-resources statement, which implicitly closes Closeables. All resources opened in a try-with-resources statement are ignored by this rule.

try (BufferedReader br = new BufferedReader(new FileReader(fileName))) {
  //...
}
catch ( ... ) {
  //...
}

See

• MITRE, CWE-459 - Incomplete Cleanup
• MITRE, CWE-772 - Missing Release of Resource after Effective Lifetime
• CERT, FIO04-J. - Release resources when they are no longer needed
• CERT, FIO42-C. - Close files when they are no longer needed
• Try With Resources

Cognitive Complexity is a measure of how hard the control flow of a method is to understand. Methods with high Cognitive Complexity will be difficult to maintain.

See

• Cognitive Complexity

Programmers should not comment out code as it bloats programs and reduces readability.

Unused code should be deleted and can be retrieved from source control history if required.

In the past, it was required to load a JDBC driver before creating a java.sql.Connection. Nowadays, when using JDBC 4.0 drivers, this is no longer required and Class.forName() can be safely removed because JDBC 4.0 (JDK 6) drivers available in the classpath are automatically loaded.

This rule raises an issue when Class.forName() is used with one of the following values:

• com.mysql.jdbc.Driver
• oracle.jdbc.driver.OracleDriver
• com.ibm.db2.jdbc.app.DB2Driver
• com.ibm.db2.jdbc.net.DB2Driver
• com.sybase.jdbc.SybDriver
• com.sybase.jdbc2.jdbc.SybDriver
• com.teradata.jdbc.TeraDriver
• com.microsoft.sqlserver.jdbc.SQLServerDriver
• org.postgresql.Driver
• sun.jdbc.odbc.JdbcOdbcDriver
• org.hsqldb.jdbc.JDBCDriver
• org.h2.Driver
• org.firebirdsql.jdbc.FBDriver
• net.sourceforge.jtds.jdbc.Driver
• com.ibm.db2.jcc.DB2Driver

Noncompliant Code Example

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;

public class Demo {
  private static final String DRIVER_CLASS_NAME = "org.postgresql.Driver";
  private final Connection connection;

  public Demo(String serverURI) throws SQLException, ClassNotFoundException {
    Class.forName(DRIVER_CLASS_NAME); // Noncompliant; no longer required to load the JDBC Driver using Class.forName()
    connection = DriverManager.getConnection(serverURI);
  }
}

Compliant Solution

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;

public class Demo {
    private final Connection connection;

    public Demo(String serverURI) throws SQLException {
        connection = DriverManager.getConnection(serverURI);
    }
}

Cognitive Complexity is a measure of how hard the control flow of a method is to understand. Methods with high Cognitive Complexity will be difficult to maintain.

See

• Cognitive Complexity

Merging collapsible if statements increases the code's readability.

Noncompliant Code Example

if (file != null) {
  if (file.isFile() || file.isDirectory()) {
    /* ... */
  }
}

Compliant Solution

if (file != null && isFileOrDirectory(file)) {
  /* ... */
}

private static boolean isFileOrDirectory(File file) {
  return file.isFile() || file.isDirectory();
}

Merging collapsible if statements increases the code's readability.

Noncompliant Code Example

if (file != null) {
  if (file.isFile() || file.isDirectory()) {
    /* ... */
  }
}

Compliant Solution

if (file != null && isFileOrDirectory(file)) {
  /* ... */
}

private static boolean isFileOrDirectory(File file) {
  return file.isFile() || file.isDirectory();
}

Cognitive Complexity is a measure of how hard the control flow of a method is to understand. Methods with high Cognitive Complexity will be difficult to maintain.

See

• Cognitive Complexity

Nesting try/catch blocks severely impacts the readability of source code because it makes it too difficult to understand which block will catch which exception.

Cognitive Complexity is a measure of how hard the control flow of a method is to understand. Methods with high Cognitive Complexity will be difficult to maintain.

See

• Cognitive Complexity

Connections, streams, files, and other classes that implement the Closeable interface or its super-interface, AutoCloseable, needs to be closed after use. Further, that close call must be made in a finally block otherwise an exception could keep the call from being made. Preferably, when class implements AutoCloseable, resource should be created using "try-with-resources" pattern and will be closed automatically.

Failure to properly close resources will result in a resource leak which could bring first the application and then perhaps the box the application is on to their knees.

Noncompliant Code Example

private void readTheFile() throws IOException {
  Path path = Paths.get(this.fileName);
  BufferedReader reader = Files.newBufferedReader(path, this.charset);
  // ...
  reader.close();  // Noncompliant
  // ...
  Files.lines("input.txt").forEach(System.out::println); // Noncompliant: The stream needs to be closed
}

private void doSomething() {
  OutputStream stream = null;
  try {
    for (String property : propertyList) {
      stream = new FileOutputStream("myfile.txt");  // Noncompliant
      // ...
    }
  } catch (Exception e) {
    // ...
  } finally {
    stream.close();  // Multiple streams were opened. Only the last is closed.
  }
}

Compliant Solution

private void readTheFile(String fileName) throws IOException {
    Path path = Paths.get(fileName);
    try (BufferedReader reader = Files.newBufferedReader(path, StandardCharsets.UTF_8)) {
      reader.readLine();
      // ...
    }
    // ..
    try (Stream<String> input = Files.lines("input.txt"))  {
      input.forEach(System.out::println);
    }
}

private void doSomething() {
  OutputStream stream = null;
  try {
    stream = new FileOutputStream("myfile.txt");
    for (String property : propertyList) {
      // ...
    }
  } catch (Exception e) {
    // ...
  } finally {
    stream.close();
  }
}

Exceptions

Instances of the following classes are ignored by this rule because close has no effect:

• java.io.ByteArrayOutputStream
• java.io.ByteArrayInputStream
• java.io.CharArrayReader
• java.io.CharArrayWriter
• java.io.StringReader
• java.io.StringWriter

Java 7 introduced the try-with-resources statement, which implicitly closes Closeables. All resources opened in a try-with-resources statement are ignored by this rule.

try (BufferedReader br = new BufferedReader(new FileReader(fileName))) {
  //...
}
catch ( ... ) {
  //...
}

See

• MITRE, CWE-459 - Incomplete Cleanup
• MITRE, CWE-772 - Missing Release of Resource after Effective Lifetime
• CERT, FIO04-J. - Release resources when they are no longer needed
• CERT, FIO42-C. - Close files when they are no longer needed
• Try With Resources

When a method is designed to return an invariant value, it may be poor design, but it shouldn't adversely affect the outcome of your program. However, when it happens on all paths through the logic, it is surely a bug.

This rule raises an issue when a method contains several return statements that all return the same value.

Noncompliant Code Example

int foo(int a) {
  int b = 12;
  if (a == 1) {
    return b;
  }
  return b;  // Noncompliant
}

If a private field is declared but not used in the program, it can be considered dead code and should therefore be removed. This will improve maintainability because developers will not wonder what the variable is used for.

Note that this rule does not take reflection into account, which means that issues will be raised on private fields that are only accessed using the reflection API.

Noncompliant Code Example

public class MyClass {
  private int foo = 42;

  public int compute(int a) {
    return a * 42;
  }

}

Compliant Solution

public class MyClass {
  public int compute(int a) {
    return a * 42;
  }
}

Exceptions

The Java serialization runtime associates with each serializable class a version number, called serialVersionUID, which is used during deserialization to verify that the sender and receiver of a serialized object have loaded classes for that object that are compatible with respect to serialization.

A serializable class can declare its own serialVersionUID explicitly by declaring a field named serialVersionUID that must be static, final, and of type long. By definition those serialVersionUID fields should not be reported by this rule:

public class MyClass implements java.io.Serializable {
  private static final long serialVersionUID = 42L;
}

Moreover, this rule doesn't raise any issue on annotated fields.

Duplicated string literals make the process of refactoring error-prone, since you must be sure to update all occurrences.

On the other hand, constants can be referenced from many places, but only need to be updated in a single place.

Noncompliant Code Example

With the default threshold of 3:

public void run() {
  prepare("action1");                              // Noncompliant - "action1" is duplicated 3 times
  execute("action1");
  release("action1");
}

@SuppressWarning("all")                            // Compliant - annotations are excluded
private void method1() { /* ... */ }
@SuppressWarning("all")
private void method2() { /* ... */ }

public String method3(String a) {
  System.out.println("'" + a + "'");               // Compliant - literal "'" has less than 5 characters and is excluded
  return "";                                       // Compliant - literal "" has less than 5 characters and is excluded
}

Compliant Solution

private static final String ACTION_1 = "action1";  // Compliant

public void run() {
  prepare(ACTION_1);                               // Compliant
  execute(ACTION_1);
  release(ACTION_1);
}

Exceptions

To prevent generating some false-positives, literals having less than 5 characters are excluded.

Duplicated string literals make the process of refactoring error-prone, since you must be sure to update all occurrences.

On the other hand, constants can be referenced from many places, but only need to be updated in a single place.

Noncompliant Code Example

With the default threshold of 3:

public void run() {
  prepare("action1");                              // Noncompliant - "action1" is duplicated 3 times
  execute("action1");
  release("action1");
}

@SuppressWarning("all")                            // Compliant - annotations are excluded
private void method1() { /* ... */ }
@SuppressWarning("all")
private void method2() { /* ... */ }

public String method3(String a) {
  System.out.println("'" + a + "'");               // Compliant - literal "'" has less than 5 characters and is excluded
  return "";                                       // Compliant - literal "" has less than 5 characters and is excluded
}

Compliant Solution

private static final String ACTION_1 = "action1";  // Compliant

public void run() {
  prepare(ACTION_1);                               // Compliant
  execute(ACTION_1);
  release(ACTION_1);
}

Exceptions

To prevent generating some false-positives, literals having less than 5 characters are excluded.