Java：将字符串解析为int并计算总和

Question

First off I want to start by saying I'm not just looking for someone to give me the answer to this problem, I am a beginner programmer and am just trying to learn as much as possible. A critique of my code and a friendly nudge in the right direction would be most appreciated! What is really confusing me is my stringParser method. I use this method to loop through the string, picking out the numbers and storing them in a new string to be parsed. What confuses me is how I would be able to add these numbers together? Here is the code:

public static int stringParser(String parsee,int parsed)
{
    int indexOfString = parsee.indexOf("=");            //Searches for an = sign since there has to be one  
    String parsee2 = "";
    int [] newArray;
    String subStringParse = parsee.substring(0,indexOfString);      //Substring made to divide string, this one is from 0 index to 1st occurence of = 
    for(int i = 0;i<subStringParse.length();i++)
    {
        if(Character.isDigit(subStringParse.charAt(i)))     //if the value is a number it is stored in a new string then parsed.
        {
            parsee2+= subStringParse.charAt(i);
            parsed = Integer.parseInt(parsee2);

        }           
    }           return parsed;

}
public static int sumInts(int a,int storedSums)
{   
    //a = new int[20];
    for(int i=0;i<a;i++)    //loops through parsed string from stringParser
    {
        storedSums += a;            //creates a new value calculating sum 
    }   
    return storedSums;
}

Answer 1

As per my guess, you want to parse something like this `12 + 34 = '.

If I'm right, then your for loop is completely wrong. It will return only 34 as integer value. You can debug your code for that.

I suggest you something like this :

int index = 0;
for(int i = 0;i<subStringParse.length();i++)
{
    if(Character.isDigit(subStringParse.charAt(i)))     //if the value is a number it is stored in a new string then parsed.
    {
        parsee2+= subStringParse.charAt(i);
        parsed = Integer.parseInt(parsee2);
    }           
    newArray[index++] = parsed; //make sure you initialize newArray.
}      
return newArray;

Answer 2

Try,

String parsee = "12+13 = 34+45 = 45+-45";
int value = 0;
String parsed = "";
for(String exp : parsee.split("=")){            
    for(String val : exp.trim().split("\\+")){
        value+=Integer.parseInt(val);
    }
    parsed+=" SUM = "+value;
    value = 0;
}
System.out.println(parsed);

Output

 SUM = 25 SUM = 79 SUM = 0