Get Integer value in final . 00 and float value in . 01 to 0.9

Question

I have this code below that is a calculator, but I have a problem: I wanted to return a value float when dividing 5 / 2 = 2.5 and returning an integer value when dividing 4 / 2 = 2 and not 2.0!

Can anyone help me on that? The code is this:

public class CalcActivity extends Activity
{
    TextView tvScreenCalc;
    String currentString="0",previusString=null;
    boolean isTempStringShown=false;
    int currentopperand=0;
    @Override public void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_calc);
        this.setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_USER_PORTRAIT);
        tvScreenCalc=(TextView)findViewById(R.id.tvScreenCalc);
        int numberButtons[]={R.id.button0,R.id.button1,R.id.button2,R.id.button3,R.id.button4,R.id.button5,R.id.button6,R.id.button7,R.id.button8,R.id.button9};
        NumberButtonClickListener numberClickListener=new NumberButtonClickListener();
        for(int id:numberButtons)
        { View v=findViewById(id);
            v.setOnClickListener(numberClickListener);
        }
        int opperandButtons[]={R.id.buttonPlus,R.id.buttonMinus,R.id.buttonDivide,R.id.buttonTimes,R.id.buttonDecimal,R.id.buttonClear,R.id.buttonEquals};
        OpperandButtonClickListener oppClickListener=new OpperandButtonClickListener();
        for(int id:opperandButtons)
        { View v=findViewById(id);
            v.setOnClickListener(oppClickListener);
        }
        setCurrentString("0");
    }
    void setCurrentString(String s)
    { currentString=s;
        tvScreenCalc.setText(s);
    }
    class NumberButtonClickListener implements OnClickListener
    { @Override public void onClick(View v)
    { if(isTempStringShown)
    { previusString=currentString;
        currentString="0";
        isTempStringShown=false;
    }
        String text=(String)((Button)v).getText();
        if(currentString.equals("0"))setCurrentString(text);
        else setCurrentString(currentString+text);
    }
    }
    class OpperandButtonClickListener implements OnClickListener
    { @Override public void onClick(View v)
    { int id=v.getId();
        if(id==R.id.buttonClear)
        { isTempStringShown=false;
            setCurrentString("0");
            previusString=null;
        }
        if(id==R.id.buttonDecimal)if(!currentString.contains("."))setCurrentString(currentString+".");
        if(id==R.id.buttonPlus||id==R.id.buttonMinus||id==R.id.buttonTimes||id==R.id.buttonDivide)
        { currentopperand=id;
            previusString=currentString;
            isTempStringShown=true;
        }
        if(id==R.id.buttonEquals)
        { double curr=Double.parseDouble(currentString);
            double result=0;
            if(previusString!=null)
            { double prev=Double.parseDouble(previusString);
                switch(currentopperand)
                { case R.id.buttonPlus: result=prev+curr; break;
                    case R.id.buttonMinus: result=prev-curr; break;
                    case R.id.buttonTimes: result=prev*curr; break;
                    case R.id.buttonDivide: result=prev/curr; break;
                }
            }
            setCurrentString(Double.toString(result));
        }
    }
    }
}

Answer 1

There are many ways, here are some:

Using Regex

static String autocasas(double numero)
{
   return String.valueOf(numero).replaceAll("(\\.?0+|\\.)$","");
}

See working on IDEONE.

Basically we’re trading any amount of zeros (0+) at the end of the line ($) by "empty" (""), and then trading any point at the end of the line also for empty.

Using operations of String

static String autocasas(double numero)
{
   String[] partes = String.valueOf(numero).split("\\.");
   if (partes[1].equals("0")) return String.valueOf(partes[0]);
   return String.valueOf(partes[0]) + "," + String.valueOf(partes[1]);
}

Upshot:

System.out.println(autocasas(5.0/7.0)); // 0,7142857142857143
System.out.println(autocasas(5.0/2.0)); // 2,5
System.out.println(autocasas(123));     // 123

See working on IDEONE.

Basically we are dividing the string in a array by decimal point.

• How we’re using a double, there will always be a decimal point to divide;

• if the second part is a "loose" zero, returns only the first;

• if you have two, concatenate with a comma.

Note that it is a base only, then you optimize.

Answer 2

A simple way to see if the result has decimal part or not is to compare it with the conversion of the value into integer. That is to say if 2.5 has no decimal part would do 2.5 == (int)2.5 that would give him false.

To get a float with two houses after the comma can use String.format using %.2f as a format specifier.

Combining these two ideas can have the following function to obtain the result as String:

public static String obterResultadoFormatado(float res){
    if (res == (int)res){
        return String.valueOf((int)res);
    }
    else {
        return String.format("%.2f", res);
    }
}

Which then calls directly with the result of the calculation:

float num1 = 5;
float num2 = 4;

Log.d("CalcActivity", obterResultadoFormatado(num1 / 2)); // 2,50
Log.d("CalcActivity", obterResultadoFormatado(num2 / 2)); // 2

Answer 3

I usually do that in these cases:

// ...
float vf = 5/2;
String [] vs = String.valueOf(vf).replace(".","_").split("_");
int vi = Integer.parseInt(vs[0]);
// ...

in the above case, I had problems with split(".") once, so I used realce(".","_") to avoid.

this code snippet does the following:
Convert your variable float to a string with String.valueOf(...);.
Split her into two using ...replace(...,...).split(...);.
Then take the first part of the created vector and convert it to integer again with Integer.parseInt(...);.

I hope that’s what you want.