java - 如何获得AttributedCharacterIterator以返回给定Attribute的运行？

假设您为一个十个字符的字符串的前五个字符分配了一个自定义的CharacterIterator.Attribute。

进一步假设您为其余字符分配了一个不同的CharacterIterator.Attribute。

为什么然后，当我调用AttributedString.getRunStart(firstAttribute)时我得到0(我希望如此)，而当我调用AttributedString.getRunStart(secondAttribute)时我也得到0？

这是我的设置代码:

final AttributedString s = new AttributedString("SQ3R9FFFFF");
final Attribute baseID = new Attribute("Base ID") {};
final Attribute fs = new Attribute("FFF") {};
s.addAttribute(baseID, "Ignored", 0, 5);
s.addAttribute(fs, "Whatever", 5, 10);
final AttributedCharacterIterator iterator = s.getIterator();
assertNotNull(iterator);

现在这是一些输出诊断信息的代码:

for (char c = iterator.first(); c != DONE; c = iterator.next()) {
  System.out.println("Character: " + c);
  System.out.println("Character index: " + iterator.getIndex());
  System.out.println("Attributes: " + iterator.getAttributes());
  System.out.println("Start for baseID: " + iterator.getRunStart(baseID));
  System.out.println("Limit for baseID: " + iterator.getRunLimit(baseID));
  System.out.println("Start for fs: " + iterator.getRunStart(fs));
  System.out.println("Limit for fs: " + iterator.getRunLimit(fs));
}

输出是这样的:

 Character: S
 Character index: 0
 Attributes: {com.foobar.collection.api.TestCaseAttributedString$1(Base ID)=Ignored}
 Start for baseID: 0
 Limit for baseID: 5
 Start for fs: 0
 Limit for fs: 5
 Character: Q
 Character index: 1
 Attributes: {com.foobar.collection.api.TestCaseAttributedString$1(Base ID)=Ignored}
 Start for baseID: 0
 Limit for baseID: 5
 Start for fs: 0
 Limit for fs: 5
 Character: 3
 Character index: 2
 Attributes: {com.foobar.collection.api.TestCaseAttributedString$1(Base ID)=Ignored}
 Start for baseID: 0
 Limit for baseID: 5
 Start for fs: 0
 Limit for fs: 5
 Character: R
 Character index: 3
 Attributes: {com.foobar.collection.api.TestCaseAttributedString$1(Base ID)=Ignored}
 Start for baseID: 0
 Limit for baseID: 5
 Start for fs: 0
 Limit for fs: 5
 Character: 9
 Character index: 4
 Attributes: {com.foobar.collection.api.TestCaseAttributedString$1(Base ID)=Ignored}
 Start for baseID: 0
 Limit for baseID: 5
 Start for fs: 0
 Limit for fs: 5
 Character: F
 Character index: 5
 Attributes: {com.foobar.collection.api.TestCaseAttributedString$2(FFF)=Whatever}
 Start for baseID: 5
 Limit for baseID: 10
 Start for fs: 5
 Limit for fs: 10
 Character: F
 Character index: 6
 Attributes: {com.foobar.collection.api.TestCaseAttributedString$2(FFF)=Whatever}
 Start for baseID: 5
 Limit for baseID: 10
 Start for fs: 5
 Limit for fs: 10
 Character: F
 Character index: 7
 Attributes: {com.foobar.collection.api.TestCaseAttributedString$2(FFF)=Whatever}
 Start for baseID: 5
 Limit for baseID: 10
 Start for fs: 5
 Limit for fs: 10
 Character: F
 Character index: 8
 Attributes: {com.foobar.collection.api.TestCaseAttributedString$2(FFF)=Whatever}
 Start for baseID: 5
 Limit for baseID: 10
 Start for fs: 5
 Limit for fs: 10
 Character: F
 Character index: 9
 Attributes: {com.foobar.collection.api.TestCaseAttributedString$2(FFF)=Whatever}
 Start for baseID: 5
 Limit for baseID: 10
 Start for fs: 5
 Limit for fs: 10

请特别注意最后一个条目，该条目报告“baseID”的“开始”为5。

最佳答案

根据Javadoc:

关于属性的运行是以下最大文本范围:

该属性在整个范围内均未定义或为null，或者为

属性值已定义，并且在整个范围内具有相同的非null值。

我认为这可能是第一个要点。对于字符0-4，fs属性未定义，因此它是有效范围。 baseID已定义，并且也是有效的。
http://download.oracle.com/javase/1,5.0/docs/api/java/text/AttributedCharacterIterator.html