IllegalThrows

Since Checkstyle 4.0

Description

Checks that specified types are not declared to be thrown. Declaring that a method throws java.lang.Error or java.lang.RuntimeException is almost never acceptable.

Properties

name description type default value since
ignoreOverriddenMethods Allow to ignore checking overridden methods (marked with Override or java.lang.Override annotation). boolean true 6.4
ignoredMethodNames Specify names of methods to ignore. String[] finalize 5.4
illegalClassNames Specify throw class names to reject. String[] Error, RuntimeException, Throwable, java.lang.Error, java.lang.RuntimeException, java.lang.Throwable 4.0

Examples

To configure the check: 

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

Example:

public class Example1 {
  void f1() throws RuntimeException {} // violation
  void f2() throws Exception {}
  void f3() throws Error {}  // violation
  void f4() throws Throwable {} // violation
  void f5() throws NullPointerException {}
  @Override
  public String toString() throws Error {
    String str = "";
    return str;
  }
}

To configure the check rejecting throws NullPointerException from methods: 

<module name="Checker">
  <module name="TreeWalker">
    <module name="IllegalThrows">
      <property name="illegalClassNames" value="NullPointerException"/>
    </module>
  </module>
</module>

Example:

public class Example2 {
  void f1() throws RuntimeException {}
  void f2() throws Exception {}
  void f3() throws Error {}
  void f4() throws Throwable {}
  void f5() throws NullPointerException {} // violation
  @Override
  public String toString() throws Error {
    String str = "";
    return str;
  }
}

To configure the check ignoring method named "func1()": 

<module name="Checker">
  <module name="TreeWalker">
    <module name="IllegalThrows">
      <property name="ignoredMethodNames" value="f1"/>
    </module>
  </module>
</module>

Example:

public class Example3 {
  void f1() throws RuntimeException {}
  void f2() throws Exception {}
  void f3() throws Error {} // violation
  void f4() throws Throwable {} // violation
  void f5() throws NullPointerException {}
  @Override
  public String toString() throws Error {
    String str = "";
    return str;
  }
}

To configure the check to warn on overridden methods: 

<module name="Checker">
  <module name="TreeWalker">
    <module name="IllegalThrows">
      <property name="ignoreOverriddenMethods" value="false"/>
    </module>
  </module>
</module>

Example:

public class Example4 {
  void f1() throws RuntimeException {} // violation
  void f2() throws Exception {}
  void f3() throws Error {}  // violation
  void f4() throws Throwable {} // violation
  void f5() throws NullPointerException {}
  @Override
  public String toString() throws Error { // violation
    String str = "";
    return str;
  }
}

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.coding

Parent Module

TreeWalker