要存储所有输入的值，您需要创建一个arraylist来查找max input number，并且要检查输入是否正确及其编号，您需要添加一个 try-catch 块，通过使用流，您可以找到输入的最大值。
注意：您还可以通过读取以下链接使用for循环来查找最大值：
java–在数组中查找最小值和最大值

Scanner input = new Scanner(System.in);

System.out.println("This program allows you to enter a series of numbers.");
System.out.println("Enter -1 when you are finished entering your numbers and");
System.out.println("the program will print the largest number entered.");
System.out.println("Enter your first number, please.");

ArrayList<Integer> numbers = new ArrayList<Integer>();

String data = "";
while (!data.equals("-1")) {
    System.out.print("Next integer (-1 to quit)? ");
    data = input.next();

    try {
        int number = Integer.parseInt(data); 
        numbers.add(number);
    } catch(Exception e) {
        System.out.println("You have entered an invalid response.");
    }
}
int max = numbers.stream().mapToInt(v -> v).max().getAsInt();
System.out.println("The largest number entered was: " + max);

您也可以简单地解决问题，而不必使用 ArrayList ，和 stream :

Scanner input = new Scanner(System.in);

System.out.println("This program allows you to enter a series of numbers.");
System.out.println("Enter -1 when you are finished entering your numbers and");
System.out.println("the program will print the largest number entered.");
System.out.println("Enter your first number, please.");

String data = "";
int max = 0;
while (!data.equals("-1")) {
    System.out.print("Next integer (-1 to quit)? ");
    data = input.next();

    try {
        int number = Integer.parseInt(data);
        if(number > max) {
            max = number;
        }
    } catch (Exception e) {
        System.out.println("You have entered an invalid response.");
    }
}

System.out.println("The largest number entered was: " + max);

下面的部分没有任何意义。您可以删除此部分：

input.nextInt();
    while (!input.hasNextInt()) ;
    {
        System.out.println("You have entered an invalid response.");
        System.out.println("Enter your first number, please.");
        input.nextInt();
    }

还有，为什么要求所有数字的总和？我想这是抄写错误。您可以删除 sum 变量也是。

int max = 0;
if (max < number) 
{
  max++;  
}

以上部分可以简单地用 Math.max() 功能

System.out.println("The largest number entered was: " + Math.max(max, number));

如果要标识整个数字序列中最大的数字，则需要遍历整个数字序列才能标识最大的数字。这意味着，只有在完成循环（在while循环之外）时才能打印最大的数字。

public static void main(String[] args) {
    Scanner input = new Scanner(System.in);

    // How to use program
    System.out.println("This program allows you to enter a series of numbers.\n" +
            "Enter -1 when you are finished entering your numbers and \n" +
            "the program will print the largest number entered. \n" +
            "Please enter your numbers(-1 to quit) : ");
    int max = 0;
    try {
        int userInput = input.nextInt();

        while (userInput != -1) {
            max = Math.max(max, userInput);
            userInput = input.nextInt();
        }
    } catch (InputMismatchException e) {
        System.out.println("Program exiting as input was invalid!");
    }
    System.out.println("The largest number entered was: " + max);
}