java.lang.StackOverflowError【该异常表示栈溢出。】

忘是亡心i 2022-03-22 15:52 404阅读 0赞

java.lang.StackOverflowError

stack size 8M

堆栈溢出，查看是否是方法递归造成。

@JvmStatic
        fun main(arg: Array<String>) {
           
            val olderContent = "一二三四五六七八九十";
            println("olderContent\t$olderContent\nreplaceAfterContent\t${testLength(olderContent, 5)}")
    
        }
    
    /***
         * 测试二分法计算可容纳的个数
         * @param name 原内容
         * @param confirmLength  允许显示的个数
         */
        fun testLength(name: String, confirmLength: Int): String {
            if (originalName.equals("")) originalName = name
            calculations++
            println("第 ${calculations} 次计算")
            var nameLength = name.length
            var isExceeding = if (nameLength > confirmLength) {
                1
            } else if (nameLength < confirmLength) {
                2
            } else {
                0
            };
            var typeName = when (isExceeding) {
                1 -> {
                    "$nameLength 大于 $confirmLength"
                }
                2 -> {
                    "$nameLength 小于 $confirmLength"
                }
                else -> {
                    "$nameLength 等于 $confirmLength"
                }
            }
            var nameHalf = 0;
            var newName = name;
            when (isExceeding) {
                1 -> { // 大于
                    nameHalf = nameLength / 2 + 1
                    newName = if (nameHalf > 0) name.substring(0, nameHalf) else name
                }
                2 -> { // 小于
                    nameHalf = Math.abs(lastName.length - nameLength) / 2 + 1
    //                var subString = if (lastName.length > nameLength) lastName else originalName
                    newName = if (nameHalf > 0) originalName.substring(0, nameLength + nameHalf) else name
                }
                else -> { // 等于
                    println("完美 perfect name $name newName $newName")
                }
            }
            println("name = $name nameLength $nameLength nameHalf $nameHalf confirmLength = $confirmLength  typeName $typeName")
            lastName = name
            if (newName != name) {
                return testLength(newName, confirmLength)
            } else {
                println("$calculations 次计算就压缩到范围内")
                return name
            }
        }
    
    打印结果：
    name = 一二三四 nameLength 4 nameHalf 2 confirmLength = 5  typeName 4 小于 5
    第 2658 次计算
    name = 一二三四五六 nameLength 6 nameHalf 4 confirmLength = 5  typeName 6 大于 5
    第 2659 次计算
    name = 一二三四 nameLength 4 nameHalf 2 confirmLength = 5  typeName 4 小于 5
    第 2660 次计算
    name = 一二三四五六 nameLength 6 nameHalf 4 confirmLength = 5  typeName 6 大于 5
    第 2661 次计算
    name = 一二三四 nameLength 4 nameHalf 2 confirmLength = 5  typeName 4 小于 5
    Exception in thread "main" java.lang.StackOverflowError
    	at java.io.Writer.write(Writer.java:157)
    	at java.io.PrintStream.write(PrintStream.java:525)
    	at java.io.PrintStream.print(PrintStream.java:669)
    	at java.io.PrintStream.println(PrintStream.java:823)
    	at MyTest.testLength(MyTest.kt:33)
    	at MyTest.testLength(MyTest.kt:72)
    	at MyTest.testLength(MyTest.kt:72)

如上所述典型的递归调用引起无线循环从而引起堆栈溢出，所以使用递归时需注意规避死循环的可能以免造成堆栈溢出。