Scanner.nextLine() 实际上并没有给出下一行
我用 Java 编写了一个非常简单的递归下降解析器，但是我附加到文件的扫描器存在一些问题。
private void ParseDataFields(Controller.TreeData data, java.util.Scanner scanner) {
java.lang.String nextline;
while(scanner.hasNextLine()) {
nextline = scanner.nextLine().trim();
if (nextline == "{") { // If we are with this, we are a new Child object declaration.
if (data.CanHaveChildren()) {
ParseDataFields(data.CreateNewChild(), scanner);
continue;
} else
FileValidationError("Attempted to give a child object to a data node that could not have one.");
}
if (nextline.endsWith("}")) // End of Child object data declaration
return;
... parse the line
问题是，当找到 { 时，该方法会递归，但实际上并未采用下一行（还有下一行）。它只是返回相同的 { 标记，这是无效的。
我一直在使用示例文件来测试这一点：
Name = scumbag
{
Name = lolcakes
}
}
使用反射，并且我确认 field=value 语法工作正常。但新孩子的开始标记却不是。
I've written a pretty simple recursive-descent parser in Java, but having some issues with the scanner I've attached to the file.
private void ParseDataFields(Controller.TreeData data, java.util.Scanner scanner) {
java.lang.String nextline;
while(scanner.hasNextLine()) {
nextline = scanner.nextLine().trim();
if (nextline == "{") { // If we are with this, we are a new Child object declaration.
if (data.CanHaveChildren()) {
ParseDataFields(data.CreateNewChild(), scanner);
continue;
} else
FileValidationError("Attempted to give a child object to a data node that could not have one.");
}
if (nextline.endsWith("}")) // End of Child object data declaration
return;
... parse the line
The problem is that when { is found, the method recurses, but the next line isn't actually taken (there is a next line). It just gives back the same { token, which is not valid.
I've been using a sample file to test this out:
Name = scumbag
{
Name = lolcakes
}
}
Used reflection and I confirmed that the field=value syntax is working fine. But the opening token for a new child isn't.
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比较 Java 中的字符串应使用
String#equals()。字符串是 Java 中的对象，而不是基元。
==将通过引用而不是值来比较对象。另请参阅：
Comparing strings in Java should be done with
String#equals().Strings are objects in Java, not primitives. The
==would compare objects by reference, not by value.See also: