Description

Attention: The break in case blocks is not counted to allow compact view.

Properties

Examples

To configure the check:

<module name="Checker">
  <module name="TreeWalker">
    <module name="NeedBraces"/>
  </module>
</module>
        

Example:

class Example1 {
  String obj = new String();
  String value = new String();
  int counter = 1;
  int count = 0;
  int num = 12;
  String o = "O";
  public boolean Example1() {
    if (obj.equals(num)) return true;
    // violation above, ''if' construct must use '{}'s.'
    if (true) {
      count = 2;
    } else
        // violation above, ''else' construct must use '{}'s.'
        return false;
    for (int i = 0; i < 5; i++) {
      ++count;}
    do // violation, ''do' construct must use '{}'s.'
        ++count;
    while (false);
    for (int j = 0; j < 10; j++);
    // violation above, ''for' construct must use '{}'s.'
    for(int i = 0; i < 10; value.charAt(12));
    // violation above, ''for' construct must use '{}'s.'
    while (counter < 10)
        // violation above, ''while' construct must use '{}'s.'
        ++count;
    while (value.charAt(12) < 5);
    // violation above, ''while' construct must use '{}'s.'
    switch (num) {
      case 1: counter++; break;
      // ok above, because break in case blocks is not counted to allow compact view
    }
    return true;
  }
}
        

To configure the check for if and else blocks:

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

Example:

class Example2 {
  String obj = new String();
  String value = new String();
  int counter = 1;
  int count = 0;
  int num = 12;
  String o = "O";
  public boolean Example2() {
    if (obj.equals(num)) return true;
    // violation above, ''if' construct must use '{}'s.'
    if (true) {
      count = 2;
    } else
        // violation above, ''else' construct must use '{}'s.'
        return false;
    for (int i = 0; i < 5; i++) {
      ++count;}
    do // ok, because DO is not a target of validation
        ++count;
    while (false);
    for (int j = 0; j < 10; j++);
    // ok above, because FOR is not a target of validation
    for(int i = 0; i < 10; value.charAt(12));
    // ok above, because FOR is not a target of validation
    while (counter < 10)
        // ok above, because WHILE is not a target of validation
        ++count;
    while (value.charAt(12) < 5);
    // ok above, because WHILE is not a target of validation
    switch (num) {
      case 1: counter++; break;
      // ok above, because break in case blocks is not counted to allow compact view
    }
    return true;
  }
}
        

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

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

Example:

class Example3 {
  String obj = new String();
  String value = new String();
  int counter = 1;
  int count = 0;
  int num = 12;
  String o = "O";
  public boolean Example3() {
    if (obj.equals(num)) return true;
    // ok above, because single line IF statement is allowed in config.
    if (true) {
      count = 2;
    } else
        // ok above, because single line ELSE statement is allowed in config.
        return false;
    for (int i = 0; i < 5; i++) {
      ++count;}
    do // violation, ''do' construct must use '{}'s.'
        ++count;
    while (false);
    for (int j = 0; j < 10; j++);
    // ok above, because single line FOR statement is allowed in config.
    for(int i = 0; i < 10; value.charAt(12));
    // ok above, because single line FOR statement is allowed in config.
    while (counter < 10)
        // violation above, ''while' construct must use '{}'s.'
        ++count;
    while (value.charAt(12) < 5);
    // ok above, because single line FOR statement is allowed in config.
    switch (num) {
      case 1: counter++; break;
      // ok above, because break in case blocks is not counted to allow compact view
    }
    return true;
  }
}
        

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

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

Next statements won't be violated by check:

class Example4 {
  String obj = new String();
  String value = new String();
  int counter = 1;
  int count = 0;
  int num = 12;
  String o = "O";
  public boolean Example4() {

    if (obj.equals(num)) return true;
    // ok above, because IF is not a target of validation
    if (true) {
      count = 2;
    } else
        // ok above, because ELSE is not a target of validation
        return false;
    for (int i = 0; i < 5; i++) {
      ++count;}
    do // ok, because DO is not a target of validation
        ++count;
    while (false);
    for (int j = 0; j < 10; j++);
    // ok above, because FOR is not a target of validation
    for(int i = 0; i < 10; value.charAt(12));
    // ok above, because FOR is not a target of validation
    while (counter < 10)
        // ok above, because WHILE is not a target of validation
        ++count;
    while (value.charAt(12) < 5);
    // ok above, because WHILE is not a target of validation
    switch (num) {
      case 1: counter++; break;
      // ok above, because break in case blocks is not counted to allow compact view
    }
    return true;
  }
}
        

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

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

Example:

class Example5 {
  String obj = new String();
  String value = new String();
  int counter = 1;
  int count = 0;
  int num = 12;
  String o = "O";
  public boolean Example5() {
    if (obj.equals(num)) return true;
    // ok above, because IF is not a target of validation
    if (true) {
      count = 2;
    } else
        // ok above, because ELSE is not a target of validation
        return false;
    for (int i = 0; i < 5; i++) {
      ++count;}
    do // ok, because DO is not a target of validation
        ++count;
    while (false);
    for (int j = 0; j < 10; j++);
    // ok above, because FOR is not a target of validation
    for(int i = 0; i < 10; value.charAt(12));
    // ok above, because FOR is not a target of validation
    while (counter < 10)
        // violation above, ''while' construct must use '{}'s.'
        ++count;
    while (value.charAt(12) < 5);
    // ok above, because WHILE is not a target of validation
    switch (num) {
      case 1: counter++; break;
      // ok above, because break in case blocks is not counted to allow compact view
    }
    return true;
  }
}
        

To configure the check to lambdas:

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

Results in following:

class Example6 {
  enum HttpMethod {GET, OPTIONS}
  Object result = new Object();
  private CustomCompletableFuture<Object> allowedFuture;
  Example6() {
    allowedFuture = new CustomCompletableFuture<>();
    allowedFuture.addCallback(result -> assertEquals("Invalid response", // violation
                    EnumSet.of(HttpMethod.GET, HttpMethod.OPTIONS), result),
            ex -> fail(ex.getMessage()));
    allowedFuture.addCustomCallback(() -> {
      return assertEquals("Invalid response",
              EnumSet.of(HttpMethod.GET, HttpMethod.OPTIONS), result);},
            ex -> fail(ex.getMessage()));}
  private Object assertEquals(String invalidResponse, EnumSet<HttpMethod> get,
                              Object result) {
    return result;}
  private String fail(String message) {
    return message;
  }}
class CustomCompletableFuture<T> {
  private CompletableFuture<T> allowedFuture;
  public CustomCompletableFuture() {
    allowedFuture = new CompletableFuture<>();
  }
  public void addCallback(java.util.function.Consumer<T> successCallback,
          java.util.function.Consumer<Throwable> failureCallback) {}
  public void addCustomCallback(java.util.function.Supplier<Object> successLambda,
          java.util.function.Consumer<Throwable> failureLambda) {}
}
        

Example of Usage

• Google Style
• Sun Style
• Checkstyle Style

Violation Messages

• needBraces

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