Java字符串太长？

Question

我在 Java 中有以下代码(由于某种原因在 C++ 中运行得很好)，它会产生错误:

int a;
System.out.println("String length: " + input.length());
for(a = 0; ((a + 1) * 97) < input.length(); a++) {
    System.out.print("Substring at " + a + ": ");
    System.out.println(input.substring(a * 97, 97));
    //other code here...
}

输出:

String length: 340
Substring at 0: HelloHelloHelloHelloHelloHelloHelloHelloHelloHelloHelloHelloHelloHelloHelloHelloHelloHelloHelloHe
Substring at 1: 
Exception in thread "AWT-EventQueue-0" java.lang.StringIndexOutOfBoundsException: String index out of range: -97
//long list of "at ..." stuff
Substring at 2: 

但是，使用长度为 200 的字符串，会产生以下输出:

String length: 200
Substring at 0: HelloHelloHelloHelloHelloHelloHelloHelloHelloHelloHelloHelloHelloHelloHelloHelloHelloHelloHelloHe
Substring at 1: 

就是这样；没有提出任何异常(exception)，只是……什么都没有。这里发生了什么？

Answer 1

第二个参数为String.substring是最后一个索引而不是子字符串的长度。所以你想要以下内容(我假设):

int a;
System.out.println("String length: " + input.length());
for(a = 0; ((a + 1) * 97) < input.length(); a++) {
    System.out.print("Substring at " + a + ": ");
    System.out.println(input.substring(a * 97, (a + 1) * 97));
    //other code here...
}