Java字符串太長？

Question

我有以下Java代碼（由於某種原因在C ++中工作得很好）會產生錯誤：

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...
}

輸出：

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，使用長度為200的字符串，將產生以下輸出：

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

這就對了; 沒有提出任何例外，只是……什么都沒有。 這是怎么回事

Answer 1

String.substring的第二個參數是最后一個索引，而不是子字符串的長度。 因此，您需要以下內容（我假設）：

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...
}