String fix for Java 10 (PR 35) about jvm-tools HOT 2 CLOSED

static String stringValue_java10(Instance obj) {
  if (obj == null) return null;
  
  if (!"java.lang.String".equals(obj.getJavaClass().getName()))
    throw new IllegalArgumentException("Is not a string: " + obj.getInstanceId() + " (" + obj.getJavaClass().getName() + ")");
    
  int UTF16 = 1;
  Boolean COMPACT_STRINGS = (Boolean) ( obj.getJavaClass().getValueOfStaticField("COMPACT_STRINGS"));
  if (COMPACT_STRINGS == null)
    return HeapWalker.stringValue(obj); // We're pre Java 9
    
  Object valueInstance = obj.getValueOfField("value");
  PrimitiveArrayInstance chars = (PrimitiveArrayInstance) ( valueInstance);
  
  byte coderField = (byte) ( obj.getValueOfField("coder"));
  byte coder = COMPACT_STRINGS ? coderField : (byte) UTF16;
  int len = chars.getLength() >> coder;
  char[] text = new char[len];
  
  List<String> values = (List) chars.getValues();
  if (coder == UTF16)
    for (int i = 0; i < text.length; i++)
      text[i] = values.get(i).charAt(0);
  else
    for (int i = 0; i < text.length; i++)
      text[i] = (char) Integer.parseInt(values.get(i));
 
  return new String(text);
}