java - 异常ArrayIndexOutOfBoundsException错误

Question

每次运行以下方法时，都会不断出现错误。即使列表不是空的，错误仍然存​​在。

public Position getBestMove() {
    int max = -10000;
    int best = -1;
    System.out.println("CALLED");
    System.out.println(successorEvaluations.size());
    // iterate over successors and return the one with the highest eval result
    for (int i = 0; i < successorEvaluations.size(); i++) { 
        if (max < successorEvaluations.get(i).score) {
            max = successorEvaluations.get(i).score;
            best = i;
        }
    }
    return successorEvaluations.get(best).pos;
}

错误输出:

java.lang.ArrayIndexOutOfBoundsException: -1
    at java.util.ArrayList.elementData(Unknown Source)
    at java.util.ArrayList.get(Unknown Source)
    at Board.getBestMove(Board.java:151)

Answer 1

best为-1，这是非法的数组索引。 if条件不满足。