Description

Rationale: If a method becomes very long it is hard to understand. Therefore, long methods should usually be refactored into several individual methods that focus on a specific task.

Properties

Examples

To configure the check so that it accepts at most 4 lines:

<module name="Checker">
  <module name="TreeWalker">
    <module name="MethodLength">
      <property name="max" value="4"/>
    </module>
  </module>
</module>
        

Example:

public class Example1 {

  // violation below, 'Method Example1 length is 5 lines (max allowed is 4)'
  public Example1() {
    int var1 = 2;
    int var2 = 4;
    int sum = var1 + var2;
  }

  // ok, as it is less than 4 lines
  public Example1(int a)  {
    int var1 = 2;
    int sum = var1 + a;
  }

  // violation below, 'Method firstMethod length is 6 lines (max allowed is 4)'
  public void firstMethod() {
    int index = 0;
    if (index < 5) {
      index++;
    }
  }

  public void secondMethod() {
    // comments are counted by default
    System.out.println("line 3");
  }

  // violation below, 'Method thirdMethod length is 5 lines (max allowed is 4)'
  public void thirdMethod() {

    // empty line above is counted by default,just like this comment
    System.out.println("line 4");
  }

  record MyBadRecord() {
    // violation below, 'Method MyBadRecord length is 5 lines (max allowed is 4)'
    public MyBadRecord {

      System.out.println("line3");
      System.out.println("line4");
    }
  }
}
        

To configure the check so that it accepts methods with at most 4 lines:

<module name="Checker">
  <module name="TreeWalker">
    <module name="MethodLength">
      <property name="tokens" value="METHOD_DEF"/>
      <property name="max" value="4"/>
    </module>
  </module>
</module>
        

Example:

public class Example2 {

  // ok, CTOR_DEF is not in configured tokens
  public Example2()  {
    int var1 = 2;
    int var2 = 4;
    int sum = var1 + var2;
  }

  // ok, CTOR_DEF is not in configured tokens
  public Example2(int a)  {
    int var1 = 2;
    int sum = var1 + a;
  }

  // violation below, 'Method firstMethod length is 6 lines (max allowed is 4)'
  public void firstMethod() {
    int index = 0;
    if (index < 5) {
      index++;
    }
  }

  public void secondMethod() {
    // comments are counted by default
    System.out.println("line 3");
  }

  // violation below, 'Method thirdMethod length is 5 lines (max allowed is 4)'
  public void thirdMethod() {

    // empty line above is counted by default,just like this comment
    System.out.println("line 4");
  }

  record MyBadRecord() {
    // ok, COMPACT_CTOR_DEF is not in configured tokens
    public MyBadRecord {

      System.out.println("line3");
      System.out.println("line4");
    }
  }
}
        

To configure the check so that it accepts methods with at most 4 lines, not counting empty lines and comments:

<module name="Checker">
  <module name="TreeWalker">
    <module name="MethodLength">
      <property name="tokens" value="METHOD_DEF"/>
      <property name="max" value="4"/>
      <property name="countEmpty" value="false"/>
    </module>
  </module>
</module>
        

Example:

public class Example3 {

  // ok, CTOR_DEF is not in configured tokens
  public Example3()  {
    int var1 = 2;
    int var2 = 4;
    int sum = var1 + var2;
  }

  // ok, CTOR_DEF is not in configured tokens
  public Example3(int a)  {
    int var1 = 2;
    int sum = var1 + a;
  }

  // violation below, 'Method firstMethod length is 6 lines (max allowed is 4)'
  public void firstMethod() {
    int index = 0;
    if (index < 5) {
      index++;
    }
  }

  public void secondMethod() {
    // countEmpty property is false,so this line doesn't count
    System.out.println("line 3");
  }

  public void thirdMethod() {

    // countEmpty property is false,so this line and the line above don't count
    System.out.println("line 4");
  }

  record MyBadRecord() {
    // ok, COMPACT_CTOR_DEF is not in configured tokens
    public MyBadRecord {

      System.out.println("line3");
      System.out.println("line4");
    }
  }
}
        

Example of Usage

• Sun Style
• Checkstyle Style

Violation Messages

• maxLen.method

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.sizes

Parent Module

TreeWalker