(CP5) How to convert the text in Texfield to a string

I'm trying to make a decimal/hexadecimal/binary converter for a college project using user input, but can't figure out any sort of way to actually use any of the stuff I input? Bear in mind I am useless at processing, so my code is messy and not complete.

Code:

import controlP5.*;

ControlP5 cp5;

void setup()
{
  size(700, 400);
  cp5 = new ControlP5(this);
  cp5.addTextfield("Decimal").setPosition(20, 100).setSize(200, 40).setAutoClear(false);
  cp5.addTextfield("Binary").setPosition(20, 170).setSize(200, 40).setAutoClear(false);
  cp5.addTextfield("Hexadecimal").setPosition(20, 240).setSize(200, 40).setAutoClear(false);
  cp5.addBang("DecimalS").setPosition(240, 100).setSize(200, 40);
  cp5.addBang("BinaryS").setPosition(240,170).setSize(200, 40);
  cp5.addBang("HexadecimalS").setPosition(240, 240).setSize(200, 40);
}

//Hexadecimal button
//Hexadecimal to Decimal conversion
public void HexadecimalS()
{
int num = 0, power = 0, res = 0;
String hex = (cp5.get(Textfield.class, "Hexadecimal").getText(), 360,130);

for(int i = hex.length()-1; i >= 0; i--)
{
  char dec = hex.charAt(i);
  String s1 = hex.substring(i, i+1);

  switch(dec)
  {
    case 'A' : num = 10; break;
    case 'B' : num = 11; break;
    case 'C' : num = 12; break;
    case 'D' : num = 13; break;
    case 'E' : num = 14; break;
    case 'F' : num = 15; break;
    default  : num = Integer.parseInt(s1);
  }
  res = res + ((num)*(int)(Math.pow(16,power)));
  power++;
}
println(res);

//Hexadecimal to Binary conversion
String bin = "";
    String binFragment = "";
    int iHex;
    hex = hex.trim();
    hex = hex.replaceFirst("0x", "");

    for(int i = 0; i < hex.length(); i++){
        iHex = Integer.parseInt(""+hex.charAt(i),16);
        binFragment = Integer.toBinaryString(iHex);

        while(binFragment.length() < 4){
            binFragment = "0" + binFragment;
        }
        bin += binFragment;
    }
    println(bin);
}


//Decimal button
//Decimal to binary conversion
public void DecimalS()
{
int deci = 142, res1 = 0, decim = deci;

String s2 = new String("");

while(deci > 0)
{
  res1 = deci%2;
  s2 = s2 + (Integer.toString(res1));
  deci = deci/2;
}

for(int i = s2.length()-1; i>=0; i--)
{
  print(s2.charAt(i));
}

println("");

//Decimal to hexadecimal conversion
String decHex = Integer.toHexString(decim);
println(decHex);
}

//Binary button
//Binary to decimal conversion
public void BinaryS()
{
String bin = cp5.get(Textfield.class, "Binary");
int binary = Integer.parseInt();
int power1 = 0, res2 = 0;
while(binary > 0)
{
  res2 = res2 + ((binary%2)*(int)(Math.pow(2,power1)));
  power1++;
  binary = binary/10;
}
println(res2);
}