NeedBraces

Since Checkstyle 3.0

Description

Checks for braces around code blocks.

Properties

name description type default value since
allowSingleLineStatement allow single-line statements without braces. boolean false 6.5
allowEmptyLoopBody allow loops with empty bodies. boolean false 6.12.1
tokens tokens to check subset of tokens LITERAL_DO , LITERAL_ELSE , LITERAL_FOR , LITERAL_IF , LITERAL_WHILE , LITERAL_CASE , LITERAL_DEFAULT , LAMBDA . LITERAL_DO , LITERAL_ELSE , LITERAL_FOR , LITERAL_IF , LITERAL_WHILE . 3.0

Examples

To configure the check: 

<module name="NeedBraces"/>

Example:

if (obj.isValid()) return true; // violation, single-line statements not allowed without braces
if (true) {                     // OK
    return true;
} else                          // violation, single-line statements not allowed without braces
    return false;
for (int i = 0; i < 5; i++) {   // OK
     ++count;
}
do                              // violation, single-line statements not allowed without braces
    ++count;
while (false);
for (int j = 0; j < 10; j++); // violation, empty loop body not allowed
for(int i = 0; i < 10; value.incrementValue()); // violation, empty loop body not allowed
while (counter < 10)          // violation, single-line statements not allowed without braces
    ++count;
while (value.incrementValue() < 5); // violation, empty loop body not allowed
switch (num) {
  case 1: counter++; break;         // OK
}

To configure the check for if and else blocks: 

<module name="NeedBraces">
  <property name="tokens" value="LITERAL_IF, LITERAL_ELSE"/>
</module>

Example:

if (obj.isValid()) return true; // violation, single-line statements not allowed without braces
if (true) {                     // OK
    return true;
} else                          // violation, single-line statements not allowed without braces
    return false;
for (int i = 0; i < 5; i++) {   // OK
     ++count;
}
do                              // OK
    ++count;
while (false);
for (int j = 0; j < 10; j++);   // OK
for(int i = 0; i < 10; value.incrementValue()); // OK
while (counter < 10)                            // OK
    ++count;
while (value.incrementValue() < 5); // OK
switch (num) {
  case 1: counter++; break;         // OK
}

To configure the check to allow single-line statements (if, while, do-while, for) without braces: 

<module name="NeedBraces">
  <property name="allowSingleLineStatement" value="true"/>
  <property name="tokens"
         value="LITERAL_IF, LITERAL_WHILE, LITERAL_DO, LITERAL_FOR"/>
</module>

Example: 

if (obj.isValid()) return true;  // OK
if (true) {                      // OK
    return true;
} else                           // OK
    return false;
for (int i = 0; i < 5; i++) {    // OK
    ++count;
}
do                               // OK
   ++count;
while (false);
for (int j = 0; j < 10; j++);                   // violation, empty loop body not allowed
for(int i = 0; i < 10; value.incrementValue()); // violation, empty loop body not allowed
while (counter < 10)                 // OK
   ++count;
while (value.incrementValue() < 5);  // violation, empty loop body not allowed
switch (num) {
  case 1: counter++; break;          // OK
}
while (obj.isValid()) return true;   // OK
do this.notify(); while (o != null); // OK
for (int i = 0; ; ) this.notify();   // OK

To configure the check to allow case, default single-line statements without braces: 

<module name="NeedBraces">
  <property name="tokens" value="LITERAL_CASE, LITERAL_DEFAULT"/>
  <property name="allowSingleLineStatement" value="true"/>
</module>

Next statements won't be violated by check: 

if (obj.isValid()) return true; // OK
if (true) {                     // OK
    return true;
} else                          // OK
    return false;
for (int i = 0; i < 5; i++) {   // OK
     ++count;
}
do                              // OK
    ++count;
while (false);
for (int j = 0; j < 10; j++);   // OK
for(int i = 0; i < 10; value.incrementValue()); // OK
while (counter < 10)                            // OK
   ++count;
while (value.incrementValue() < 5); // OK
switch (num) {
  case 1: counter++; break;         // OK
  case 6: counter += 10; break;     // OK
  default: counter = 100; break;    // OK
}

To configure the check to allow loops (while, for) with empty bodies: 

<module name="NeedBraces">
  <property name="allowEmptyLoopBody" value="true"/>
  <property name="tokens" value="LITERAL_WHILE, LITERAL_FOR"/>
</module>

Example: 

if (obj.isValid()) return true; // OK
if (true) {                     // OK
    return true;
} else                          // OK
    return false;
for (int i = 0; i < 5; i++) {   // OK
     ++count;
}
do                              // OK
    ++count;
while (false);
for (int j = 0; j < 10; j++);   // OK
for(int i = 0; i < 10; value.incrementValue()); // OK
while (counter < 10)           // violation, single-line statements not allowed without braces
   ++count;
while (value.incrementValue() < 5); // OK
switch (num) {
case 1: counter++; break;           // OK
}

To configure the check to lambdas: 

<module name="NeedBraces">
  <property name="tokens" value="LAMBDA"/>
  <property name="allowSingleLineStatement" value="true"/>
</module>

Results in following: 

allowedFuture.addCallback(result -> assertEquals("Invalid response",
  EnumSet.of(HttpMethod.GET, HttpMethod.OPTIONS), result), // violation, lambda spans 2 lines
  ex -> fail(ex.getMessage())); // OK

allowedFuture.addCallback(result -> {
  return assertEquals("Invalid response",
    EnumSet.of(HttpMethod.GET, HttpMethod.OPTIONS), result);
  }, // OK
  ex -> fail(ex.getMessage()));

Example of Usage

Violation Messages

All messages can be customized if the default message doesn't suit you. Please see the documentation to learn how to.

Package

com.puppycrawl.tools.checkstyle.checks.blocks

Parent Module

TreeWalker