How to subtract two string values in java

Question

Am having two string contaning integer values how can i subtract this to string.

 String addquantity = quantity1.getText().toString();
 String subquantity = quantity2.getText().toString();
 int final_ = Integer.parseInt(addquantity) - Integer.parseInt(subquantity);

I tried many methods but its showing error , help me to subtract the value in string.

quantity1 and quantity2 containing the integer value like 3 ,5 — Sivakumar S, Mar 26 '16 at 17:03
Maybe your EditTexts are not initialized yet, something like "quantity1 = (EditText) findViewById(R.id.YOUR_EDIT_TEXT_ID)" you need for both — Manuel Pamplona, Mar 26 '16 at 17:06
@MounirElfassi, if they were null, he would get a NullPointerException on line 1 or 2 — Sid, Mar 26 '16 at 17:06
Yes mounir & manuel , you are correct i forgot to get the value of edittext which is declared inside the loop. — Sivakumar S, Mar 26 '16 at 17:18
I already post the correct answer so you can upvote for it, glad to know it's working. — Manuel Pamplona, Mar 26 '16 at 17:24
Possible duplicate of [What is a Null Pointer Exception, and how do I fix it?](http://stackoverflow.com/questions/218384/what-is-a-null-pointer-exception-and-how-do-i-fix-it) — Mike M., Mar 27 '16 at 03:09

score 1 · Answer 1 · edited Mar 29 '16 at 02:36

1

Maybe your EditTexts are not initialized, you need something like quantity1 = (EditText) findViewById(R.id.YOUR_EDIT_TEXT_ID) for both.

edited Mar 29 '16 at 02:36

Evin1_

12,292
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answered Mar 26 '16 at 17:20

Manuel Pamplona

217
1
5

score 0 · Answer 2 · answered Mar 26 '16 at 17:15

Check what you are passing...check my example.

package general;

public class TestNumberFormat {

    public static void main(String[] args){
     String addquantity = "40";
     String subquantity = "30";
     int final_ = Integer.parseInt(addquantity) - Integer.parseInt(subquantity);
     System.out.println("PRINT :" + final_);

     String addquantity1 = "D40";
     String subquantity1 = "D30";
     int final1_ = Integer.parseInt(addquantity1) - Integer.parseInt(subquantity1);
     System.out.println("PRINT :" + final1_);

  }
}

Output:

PRINT :10

Exception in thread "main" java.lang.NumberFormatException: For input string: "D40"  
at       java.lang.NumberFormatException.forInputString(NumberFormatException.java:65)  
at java.lang.Integer.parseInt(Integer.java:580)
at java.lang.Integer.parseInt(Integer.java:615)
at general.TestNumberFormat.main(TestNumberFormat.java:13)

Even a space can lead to issues. use trim() – Suparna Mar 26 '16 at 17:16 — Suparna, Mar 26 '16 at 17:16

score 0 · Answer 3 · answered Mar 26 '16 at 17:16

0

Maybe you got an space in your string. Use following

String addquantity = quantity1.getText().toString().trim();
String subquantity = quantity2.getText().toString().trim();

answered Mar 26 '16 at 17:16

Mario Mitterbauer

437
7
13

trim() does not solve the problem because the problem is one or both are null. – Manuel Pamplona Mar 26 '16 at 17:18

How to subtract two string values in java

3 Answers3