CODEWITHSUNDEEP
javastringconcatenationtostringparseint
user4818847
user4818847

Reputation:

Java weird Integer.parseInt issue (new to java)

Hello I want to string concatenate two numbers as in the code below:

tmp2 = Integer.toString(preresult) + tmp2.substring(2, tmp2.length());

Tmp2 is a string declared from before. Preresult is a integer that contains a number. If I print this line it adds the two values instead of string concatenation.

If I change Integer.toString(preresult) to for example Integer.toString(5) it string concatenates as I would like it to do. But having Integer.toString(preresult) it adds the two numbers instead of string concatenating.

The code for preresult :

preresult = Integer.parseInt(tmp2.substring(0, 1)) + Integer.parseInt(tmp2.substring(1, 2));

//It picks numbers from tmp2 and adds them together. If I print preresult it gives me a int (for example 9)

Once again please help me concatenate these two strings instead of adding them:

tmp2 = Integer.toString(preresult) + tmp2.substring(2, tmp2.length());

New to java please mercy :)

Upvotes: 0

Views: 245

Answers (2)

mastov
mastov

Reputation: 2982

The line you are giving us does concatenate the Strings, but maybe you got confused because the line before sums them:

// tmp2 == "45" (taken from your comment)

preresult = Integer.parseInt(tmp2.substring(0, 1)) + Integer.parseInt(tmp2.substring(1, 2));
//                           |------ "4" -------|                     |-------- "5" -----|
//          |--------------- 4 -----------------|    |------------------ 5 --------------|
// preresult == 4 + 5 == 9

println(tmp2); // prints the "45" (unchanged)

tmp2 = Integer.toString(preresult) + tmp2.substring(2, tmp2.length());
//                      |-- 9 --|                     |"45"|
//     |----------- "9" ---------|   |------------- "" -------------|
// tmp2 == "9" + "" == "9"

println(tmp2); // prints "9"

So your first line sums the two digits 4 and 5, which results in 9. The line you had given us just concatenates that result "9" (as String) with another empty String and therefore keeps the "9".

Upvotes: 0

ABHISHEK RANA
ABHISHEK RANA

Reputation: 327

Are you looking for this type of operation

class String1
{
    public static void main(String args[])
    {
        int a = 100;
        int b = 200;
        String s1 = Integer.toString(a);
        String s2 = Integer.toString(b);
        System.out.println(s1+s2);
    }
}

Output - 100200

Upvotes: 1

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