DynamicMessage.java 文件源码

public Builder setField(FieldDescriptor field, Object value) {
  verifyContainingType(field);
  ensureIsMutable();
  if (field.getType() == FieldDescriptor.Type.ENUM) {
    verifyEnumType(field, value);
  }
  OneofDescriptor oneofDescriptor = field.getContainingOneof();
  if (oneofDescriptor != null) {
    int index = oneofDescriptor.getIndex();
    FieldDescriptor oldField = oneofCases[index];
    if ((oldField != null) && (oldField != field)) {
      fields.clearField(oldField);
    }
    oneofCases[index] = field;
  }
  fields.setField(field, value);
  return this;
}