java My code在我的代码中出现数组越界异常，但在前两次输入出错后，它将运行并崩溃

Question

do {
     if (counter%2==0 && HP1[choice2] <= 0) {
       System.out.println("You cannot switch to that pokemon it has already fainted, choose someone else");
       choice2 = reader.nextInt();      
     } 
     else if (counter%2==0 && choice2 == index1) {
       System.out.println(myParty[index1] + " is already in battle. Please select a different pokemon.");
       choice2 = reader.nextInt();
     }
} while (counter%2==0 && HP1[choice2] <= 0 || counter%2==0 && choice2 == index1);

这段代码打乱了我的整个项目，我用它来限制某些行为，但它破坏了我的整个游戏，有人能告诉我哪里出了问题吗。程序将运行，但在显示异常的第二次用户输入后崩溃

Answer 1

了解更多的上下文会很有帮助，尤其是：index1的值来自哪里？它是如何改变的

调试数组越界异常的提示：在访问数组之前，打印数组大小和即将访问的索引。例如，在代码中，在第一个if语句之前添加：

System.out.println("HP1 array size: " + HP1.length);
System.out.println("About to access index: " + choice2);

System.out.println("myParty array size: " + myParty.length);
System.out.println("About to access index: " + index1);

通过这种方式，您可以将问题简化为更具体的问题（例如，为什么choice2或index1是某个特定值）

通常，在访问数组之前检查索引是否超出范围也是一个好主意，尤其是在处理用户输入时（就像处理reader对象时那样）

你可以这样检查一下

do {
     if (choice2 < 0 || choice2 > (HP1.length - 1) || index1 < 0 || index1 > (myParty.length - 1)) {
       // handle the error
     }
     else if (counter%2==0 && HP1[choice2] <= 0) {
       System.out.println("You cannot switch to that pokemon it has already fainted, choose someone else");
       choice2 = reader.nextInt();      
     } 
     else if (counter%2==0 && choice2 == index1) {
       System.out.println(myParty[index1] + " is already in battle. Please select a different pokemon.");
       choice2 = reader.nextInt();
     }
} while (counter%2==0 && HP1[choice2] <= 0 || counter%2==0 && choice2 == index1);