Konversi Suhu dengan JAVA

Assalamualaikum kawan.. selamat malam nih.. aduh, ternyata masih banyak juga ya yg lagi ol FB.
pdhal udah malem gini..
oiya, ane mau share lagi nih tentang java, ane buat program konversi suhu.
biar lebih gampang kalo ada yang mau konversi. jadi, G perlu repot buat ngitung.
langsung aja ya ane kasih source codenya..
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/*
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 */

package Tugas_coba;

/**
 *
 * @author pradikta
 */
public class konvertsuhu {
    public static void main(String[]okky){
System.out.println("Konversi suhu simpel dengan java");
System.out.println("--------------------------------");
    String a= ""; // DI inputkan celcius, reaumur, fahrenheit, atau kelvin
    int b= 0; // Di inputkan bilangan bulat
    double suhuC = 0;
    double suhuF = 0;
    double suhuK = 0;
    double suhuR = 0;
try{
    if(a == "celcius")
    {   suhuK = b + 237.15;
        suhuF = (b * 1.8) + 32;
        suhuR = b * 0.8;
        System.out.println("Suhu Celcius = " + b);
        System.out.println("suhu Kelvin = " + suhuK);
        System.out.println("Suhu Fahrenheit = " + suhuF);
        System.out.println("Suhu Reaumur = " + suhuR);
    }
 else
    if(a == "fahrenheit"){
     suhuK = (b + 459.67)/ 1.4;
     suhuR = (b - 32)/ 2.25;
     suhuC = (b - 32)/ 1.8;
     System.out.println("Suhu Fahrenheit = " + b);
     System.out.println("Suhu Kelvin = " + suhuK);
     System.out.println("Suhu Reaumur = " + suhuR);
     System.out.println("Suhu Celcius = " + suhuC);

    }
 else
     if(a == "reaumur"){
     suhuK = (b/0.8)+ 273.15;
     suhuC = b/0.8;
     suhuF = (b*2.25)+32;
     System.out.println("Suhu Reaumur = " + b);
     System.out.println("Suhu Kelvin = " + suhuK);
     System.out.println("Suhu Celcius = " + suhuC);
     System.out.println("Suhu Fahrenheit = " + suhuF);
     }
 else
     if(a == "kelvin"){
     suhuC = b-273.15;
     suhuF = (b*1.8)-459.67;
     suhuR = (b-273.15)*0.8;
     System.out.println("Suhu Kelvin = " + b);
     System.out.println("Suhu Celcius = " + suhuC);
     System.out.println("Suhu Fahrenheit = " + suhuF);
     System.out.println("Suhu Reaumur = " + suhuR);
     }
 else{System.out.println("Kemungkinan terjadi kesalahan input");}
   
        }
catch (Exception e){}

    }

}
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nah, di atas adalah codenya, monggo di coba dan di utak atik, pasti kawan2 lebih jago drpda ane.
sekian dulu ya dari ane, wassalamualaikum....