Resistance Calculator App

This is the java file for a resistance calculator. I simply used 4 spinners to select the color values. It'll calculate the resistance value on clicking submit. I'll upload the XML file on request.

package com.example.resistancecalcu;

import android.app.Activity;
import android.os.Bundle;
import android.view.Menu;
import android.view.View;
import android.widget.ArrayAdapter;
import android.widget.Spinner;
import android.widget.TextView;

public class MainActivity extends Activity {
String band1,band2,band3,band4;
Spinner spinner1,spinner2,spinner3,spinner4;
TextView tv;
int a,b,c,d,temp,x,p=0;
String let;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        spinner1=(Spinner) findViewById(R.id.spinner1);
        tv=(TextView)findViewById(R.id.textView1);
        spinner2=(Spinner) findViewById(R.id.spinner2);
        spinner3=(Spinner) findViewById(R.id.spinner3);
        spinner4=(Spinner) findViewById(R.id.spinner4);
  ArrayAdapter<CharSequence> adapter = ArrayAdapter.createFromResource(this,
        R.array.colors, android.R.layout.simple_spinner_item);
  adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
  ArrayAdapter<CharSequence> adapter1 = ArrayAdapter.createFromResource(this,
       R.array.fourth, android.R.layout.simple_spinner_item);
 adapter1.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
spinner1.setAdapter(adapter);
spinner2.setAdapter(adapter);
spinner3.setAdapter(adapter);
spinner4.setAdapter(adapter1);

    }
    public void value(View v)
    {
    band1=spinner1.getSelectedItem().toString();
    band2=spinner2.getSelectedItem().toString();
    band3=spinner3.getSelectedItem().toString();
    band4=spinner4.getSelectedItem().toString();
    if(band1.equals("Black"))
    a=0;
    else if(band1.equals("Brown"))
    a=1;
    else if(band1.equals("Red"))
    a=2;
    else if(band1.equals("Orange"))
    a=3;
    else if(band1.equals("Yellow"))
    a=4;
    else if(band1.equals("Green"))
    a=5;
    else if(band1.equals("Blue"))
    a=6;
    else if(band1.equals("Violet"))
    a=7;
    else if(band1.equals("Grey"))
    a=8;
    else
    a=9;
    if(band2.equals("Black"))
    b=0;
    else if(band2.equals("Brown"))
    b=1;
    else if(band2.equals("Red"))
    b=2;
    else if(band2.equals("Orange"))
    b=3;
    else if(band2.equals("Yellow"))
    b=4;
    else if(band2.equals("Green"))
    b=5;
    else if(band2.equals("Blue"))
    b=6;
    else if(band2.equals("Violet"))
    b=7;
    else if(band2.equals("Grey"))
    b=8;
    else
    b=9;
 
    temp=a*10+b;
    if(band3.equals("Black"))
    {
    c=0;
    x=1;
    let="";
   
    }
    else if(band3.equals("Brown"))
    {
    c=1;
    x=10;
    let="";
   
    }
    else if(band3.equals("Red"))
    {
    c=2;
    x=100;
    let="";
    }
    else if(band3.equals("Orange"))
    {
    c=3;
    x=1;
    let="K";
    }
    else if(band3.equals("Yellow"))
    {
    c=4;
    x=10;
    let="K";
    }
    else if(band3.equals("Green"))
    {
    c=5;
    x=100;
    let="K";
    }
    else if(band3.equals("Blue"))
    {
    c=6;
    x=1;
    let="M";
    }
    else if(band3.equals("Violet"))
    {
    c=7;
    x=10;
    let="M";
    }
    else if(band3.equals("Grey"))
    {
    c=8;
    x=100;
    let="M";
    }
    else
    {
    c=9;
    x=1;
    let="M";
    }
    if(band4.equals("Silver"))
    {
    p=10;
    }
    else if(band4.equals("Gold"))
    {
    p=5;
    }
 
 
    if(band4.equals("No color"))
    tv.setText(""+temp*x+" "+let+" ohm");
    else
    tv.setText(""+temp*x+" "+let+" ohm"+" "+p+"%");
 
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.activity_main, menu);
        return true;
    }
 
}