在执行tree的buid方法出现如下错误

严重: Servlet.service() for servlet [contacts] in context with path [/efo] threw exception [Handler processing failed; nested exception is java.lang.StackOverflowError] with root cause

java.lang.StackOverflowError

at java.util.AbstractList.listIterator(Unknown Source)

at java.util.AbstractSequentialList.iterator(Unknown Source)

at com.efo.common.tree.Tree.buildTree(Tree.java:38)

at com.efo.common.tree.Tree.buildTree(Tree.java:42)

at com.efo.common.tree.Tree.buildTree(Tree.java:42)

at com.efo.common.tree.Tree.buildTree(Tree.java:42)

at com.efo.common.tree.Tree.buildTree(Tree.java:42)

at com.efo.common.tree.Tree.buildTree(Tree.java:42)

at com.efo.common.tree.Tree.buildTree(Tree.java:42)

at com.efo.common.tree.Tree.buildTree(Tree.java:42)

at com.efo.common.tree.Tree.buildTree(Tree.java:42)

at com.efo.common.tree.Tree.buildTree(Tree.java:42)

at com.efo.common.tree.Tree.buildTree(Tree.java:42)

at com.efo.common.tree.Tree.buildTree(Tree.java:42)

at com.efo.common.tree.Tree.buildTree(Tree.java:42)

at com.efo.common.tree.Tree.buildTree(Tree.java:42)

at com.efo.common.tree.Tree.buildTree(Tree.java:42)

at com.efo.common.tree.Tree.buildTree(Tree.java:42)

at com.efo.common.tree.Tree.buildTree(Tree.java:42)

at com.efo.common.tree.Tree.buildTree(Tree.java:42)

at com.efo.common.tree.Tree.buildTree(Tree.java:42)

at com.efo.common.tree.Tree.buildTree(Tree.java:42)

at com.efo.common.tree.Tree.buildTree(Tree.java:42)

at com.efo.common.tree.Tree.buildTree(Tree.java:42)

at com.efo.common.tree.Tree.buildTree(Tree.java:42)