是什么导致Java（冰雹序列）在我的程序中崩溃 [英] What's causing Java (hailstone sequence) to crash in my program

问题描述

我做了一个程序来执行（通常称为）hailstone序列，该程序基本上是这样做的：

创建一个 int （value）并为其赋值。

creates an int (value) and assign it a value.

如果int是偶数，则除以2。

If the int is even, divide it by two.

如果int是奇数，则将其乘以3并加1。继续这个过程，直到n等于一。

If the int is odd, multiply it by three and add one. Continue this process until n is equal to one.

它似乎与大多数数字一起工作正常，但这个数字99888769，应用程序挂起一个负整数。这是为什么？他们说没有人能够证明它停止了，我没想到我已经解决了这个问题。但知道为什么我的应用停止会很有趣。 -

    private void hailStoneSequence(){
    int value = 99888769;
    int i = 0;
    boolean trueOrFalse = isOddOrEven (value);
    while (value != 1){
        while (trueOrFalse == true && value != 1){
            i++;
            int previousValue = value;
            value = value / 2;
            println( previousValue +" is even, so I take half: "+value);
            trueOrFalse = isOddOrEven (value); // returning true or false, and inserting the newly divided number. So that it breaks loop when nescesary.
        }
            while (trueOrFalse == false && value != 1){
                i++;
                int previousValue = value;
                value = (value * 3) + 1;
                println (previousValue +" is odd, so I make 3n+1: "+value); 
                trueOrFalse = isOddOrEven (value);  
            }
                }       
    println ("\n\nThe process took "+i+" to reach "+value);
}

private boolean isOddOrEven(int value){
    /*
     * Takes an value and returns true, if that number is even.
     * Else it returns false.
     */
    if (value % 2 != 0){
    return false;
    }else{
        return true;
    }
}

}

推荐答案

随着你不断增加 int s，他们最终会（看起来像一个惊人的行为）变成负面因为你超过了int类型的最大值（2 ^ 31-1），即你最终改变了用于存储数字符号的位（int的二进制表示）。请改用 long 。

As you keep increasing ints, they will eventually (in what might seem like a startling behavior) become negative because you are surpassing the maximum value of the int type (2^31-1), i.e. you end up changing the bit (of the int's binary representation) that is used to store the sign of the number. Use long instead.

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