java - 减去字符串

Question

我被要求创建一个 JOptionPane该程序接受用户想要的任意数量的数字(作为字符串)并将它们相加。我想到了这样的伪:

1. 制作int Total = 0
2. 接收字符串 X 形式的输入
3. 循环:for (int i = 0; i<=X.length();i++)
   1. 创建另一个字符串 S1它获取从开头到第一个空格的数字
   2. 转换S1转化为一个数字并将其添加到总计
   3. 减去S1来自X ，然后开始循环
4. 显示总计

所以，我的问题是减去 S1来自X 。

到目前为止我的代码:

public static void main(String[] args) {
int total = 0;
    String x = JOptionPane.showInputDialog("enter nums please");
    for (int i = 0; i<=x.length();i++){
        String s1 = x.substring (0, x.indexOf(' '));
        total += Integer.parseInt(s1);  
        x = x - s1;
    }
    JOptionPane.showMessageDialog(null, "the sum is" + total); }

Answer 1

如果你还没有学习数组，你可以这样实现:

public static void main(String[] args){
        int total = 0;
        String x = "12 7";
        String s1 = x.trim(); //trim the string
        while(!s1.isEmpty()){ //loop until s1 is not empty
            int index = x.indexOf(' ');//search the index for a whitespace
            if(index != -1){ //we found a whitespace in the String !
                s1 = s1.substring(0, index); //substract the right number
                total += Integer.parseInt(s1); 
                x = x.substring(index+1).trim(); //update the String x by erasing the number we just added to total
                s1 = x; //update s1
            } else {
                total += Integer.parseInt(s1); //when there is only one integer left in the String
                break; //break the loop this is over
            }
        }
        System.out.println(total);
    }