JetBrains/intellij-community · error · IllegalArgumentException

attribute '{attributeName}' is not a proper integer: {str}

Error message

attribute '{attributeName}' is not a proper integer: {str}

What it means

Thrown by LwXmlReader.getRequiredInt when a required attribute's trimmed value cannot be parsed by Integer.parseInt. Grid layout metadata (row/column size, indentation, span counts, minimum size values) is stored as integer attributes; a non-numeric or malformed value fails with IllegalArgumentException naming the attribute and the bad string.

Source

Thrown at java/compiler/forms-compiler/src/com/intellij/uiDesigner/lw/LwXmlReader.java:66

      return value;
    }
    else{
      throw new IllegalArgumentException("attribute '" + attributeName + "' is required: "+element);
    }
  }

  static String getOptionalString(final Element element, final String attributeName, final String defaultValue) {
    final String value = element.getAttributeValue(attributeName);
    return value != null ? value.trim() : defaultValue;
  }

  public static int getRequiredInt(final Element element, final String attributeName) {
    final String str = getRequiredString(element, attributeName);
    try {
      return Integer.parseInt(str);
    }
    catch (NumberFormatException e) {
      throw new IllegalArgumentException("attribute '" + attributeName + "' is not a proper integer: " + str);
    }
  }

  static int getOptionalInt(final Element element, final String attributeName, final int defaultValue) {
    final String str = element.getAttributeValue(attributeName);
    if (str == null) {
      return defaultValue;
    }
    try {
      return Integer.parseInt(str);
    }
    catch (NumberFormatException e) {
      throw new IllegalArgumentException("attribute '" + attributeName + "' is not a proper integer: " + str);
    }
  }

  public static boolean getOptionalBoolean(final Element element, final String attributeName, final boolean defaultValue) {
    final String str = element.getAttributeValue(attributeName);

View on GitHub (pinned to be881553f2)

Solutions

  1. Set the attribute named in the message to a plain integer literal (e.g. height="20").
  2. If the value was meant to be computed/sized, use the designer's own sizing flags instead of custom text.
  3. Re-save the form from the GUI designer to restore canonical numeric values.

Example fix

<!-- before -->
<row height="auto"/>

<!-- after -->
<row height="20" resizable="true"/>
Defensive patterns

Strategy: validation

Validate before calling

// Before parsing int attributes from generated XML
if (!str.trim().matches("-?\\d+")) throw new IllegalStateException("Attribute '" + attr + "' must be an integer, got: " + str);

Try / catch

try { LwXmlReader.getRequiredInt(element, attr); } catch (IllegalArgumentException e) { if (e.getMessage().contains("not a proper integer")) { /* replace symbolic/unit value with a plain integer */ } else throw e; }

Prevention

When it happens

Trigger: A form-XML attribute read via getRequiredInt contains a non-integer, e.g. <row height="auto"/> or <grid row="1.5"/>, or whitespace-only after trimming, or a value with a unit suffix like "20px".

Common situations: Hand-editing form files and replacing numeric layout attributes with descriptive text; scripts templating forms with placeholder tokens left in numeric fields; locale-related edits inserting comma decimal separators into integer fields.

Related errors

AI-assisted analysis of JetBrains/intellij-community@be881553f2 (2026-08-14). Data as JSON: /api/errors/c8f62de68f682eb3. Report an issue: GitHub.