Java: Turn a math equation into a String expression?

Question

I'm new to Java and I'm trying to figure out how I would write a math expression that displays the values of the variables on one line, then on the next line does the math?

Here is what I thought would work, but it just prints out the answers instead of the string representations on the top line of the addStuff() method.

public class DoSomeMath {
    int num1C = 3;
    int num1A = 7;
    public void addStuff(){
        //Show the Equation//
        System.out.println("Adding num1C + num1A: " + Integer.toString(num1C) + Integer.toString(num1A));
        //Show the Answer//
        System.out.println("Adding num1C + num1A: " + num1C + num1A);
    }
}

score 2 · Answer 1 · answered May 13 '15 at 16:48

You are using a + operator in System.out.println(String str) When you use + sign for string's it normally does the task of appending the string in the string pool.

//Show the Equation//
System.out.println("Adding num1C + num1A: " + Integer.toString(num1C) + 
"+"+ Integer.toString(num1A));
//Show the Answer//
System.out.println("Adding num1C + num1A: " + " " + (num1C + num1A));

So understand the use of + arithmetic operator with Strings and integer value.

GreySage · Answer 2 · 2015-05-13T18:38:56.130

0

Try making it + Integer.toString(num1C) + " + " + Integer.toString(num1A)

Any static characters you can enter as a string, and then concatenate with the variables.

edited May 13 '15 at 18:38

answered May 13 '15 at 16:47

GreySage

1,153
19
39

How do I get the "+" sign then to go between the two variables? – Richard Newman May 13 '15 at 16:50

score 0 · Answer 3 · answered May 13 '15 at 16:50

0

Your num1C and num1A are getting converted to Strings and appended as Strings. Use parentheses so the math happens first, then the String append last.

System.out.println("Adding num1C + num1A: " + (num1C + num1A));

answered May 13 '15 at 16:50

Sean N.

963
2
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score 0 · Accepted Answer · answered May 13 '15 at 16:50

0

Achieving the effect you want for this is even easier than you are making it:

//Show the Equation//
System.out.println("Adding num1C + num1A: " + num1C + "+" + num1A);
//Show the Answer//
System.out.println("Adding num1C + num1A: " + (num1C + num1A));

The first line concatenates them as strings, while the second line forces the integer addition via parenthesis.

answered May 13 '15 at 16:50

Corey Hoffman

143
8

Thank you! I knew it was something simple that I was overlooking. XD – Richard Newman May 13 '15 at 16:54

score 0 · Answer 5 · answered May 13 '15 at 16:52

Try this:

public class DoSomeMath {
    int num1C = 3;
    int num1A = 7;
    public void addStuff(){
        //Show the Equation//
        System.out.println("Adding num1C + num1A: " + num1C + " + " + num1A);
        //Show the Answer//
        System.out.println("Adding num1C + num1A: " + (num1C + num1A));
    }
}

Java: Turn a math equation into a String expression?

5 Answers5