StringBuilder错误复现：java.lang.ArrayIndexOutOfBoundsException: dstBegin > dst.length. dstBegin=29496...

用StringBuilder的append方法时，会出现挂掉的情况，是多线程导致的，报错信息如下

AndroidRuntime: FATAL EXCEPTION: Thread-10
AndroidRuntime: Process: com.xxxxx, PID: 4010
AndroidRuntime: java.lang.ArrayIndexOutOfBoundsException: dstBegin > dst.length. dstBegin=294965, dst.length=294910
AndroidRuntime:        at java.lang.String.getChars(String.java:802)
AndroidRuntime:        at java.lang.AbstractStringBuilder.append(AbstractStringBuilder.java:452)
AndroidRuntime:        at java.lang.StringBuilder.append(StringBuilder.java:137)
AndroidRuntime:        at com.android.tools.analysis.speedtest.guangdong.ui.FragmentStartReady$onViewCreated$4$1.invoke(FragmentStartReady.kt:130)
AndroidRuntime:        at com.android.tools.analysis.speedtest.guangdong.ui.FragmentStartReady$onViewCreated$4$1.invoke(FragmentStartReady.kt:39)
AndroidRuntime:        at kotlin.concurrent.ThreadsKt$thread$thread$1.run(Thread.kt:30)

复现代码如下

val sb = StringBuilder()
for (i in 0 until 10) {
    thread {
        for (i1 in 0 until 10000) {
            sb.append("some string")
        }
    }
}

解决办法是使用StringBuffer

参考java - What actual cause the StringBuilder fails in multi threading environment - Stack Overflow