如何从Java中的非二叉树返回随机字符串

Question

I have a method to return a String from a non binary tree but its throwing "IllegalArguementException" What am I doing wrong.

 public String getRandomWord(Node node, String word){
      Random randomGenerator = new Random(); 
      randomInt = 0;
      current = node;
      if(node.getChildren() == null){
           //System.out.println(node.getData());
           return word;
      }
      while(node.getChildren() != null){
           randomInt = randomGenerator.nextInt(node.getChildren().size());
           randomInt = randomGenerator.nextInt(2);
           current = node.getChildren().get(randomInt);
           word += current.getData(); 
           //System.out.print(current.getData()+"\n");
           getRandomWord(current, word);
      }
      return word;
}

---

 Exception in thread "main" java.lang.IndexOutOfBoundsException: Index: 0, Size: 0
 at java.util.ArrayList.rangeCheck(ArrayList.java:604)
 at java.util.ArrayList.get(ArrayList.java:382)
 at treeapp.Tree.getRandomWord(Tree.java:71)
 at treeapp.Tree.getRandomWord(Tree.java:74)
 at treeapp.Tree.getRandomWord(Tree.java:74)
 at treeapp.Tree.getRandomWord(Tree.java:74)
 at treeapp.Tree.getRandomWord(Tree.java:74)
 at treeapp.Tree.getRandomWord(Tree.java:74)
 at treeapp.Tree.getRandomWord(Tree.java:74)
 at treeapp.Main.main(Main.java:34)
 Java Result: 1

Answer 1

I think you meant to delete this line, which will overwrite the previous random number and assumes that there are always 2 children.

randomInt = randomGenerator.nextInt(2);

Also, I'm not sure exactly what the method is supposed to do, but you may want to change the while to an if if I understand it correctly.

Finally, change if(node.getChildren() == null) to if(node.getChildren().size()==0) . When the node has no children, getChildren() returns an empty list, not null .