Error – Illegal static declaration in inner class

Illegal static declaration in inner class Mobile.mymobile
  modifier 'static' is only allowed in constant variable declarations
Line 75,  public static void main(String[] args) {  

/**
 * to write a simple java class Mobile that models a mobile phone.
 * 
 * @author (jamal) 
 * @version (14/10/13)
 */
public class Mobile
{
    // type of phone
    private String phonetype;
    // size of screen in inches
    private int screensize;
    // menory card capacity
    private int  memorycardcapacity;
    // name of present service provider
    private String serviceprovider;
    // type of contract with service provider
    private int typeofcontract;
    // camera resolution in megapixels
    private int cameraresolution;
    // the percentage of charge left on the phone
    private int checkcharge;
    // wether the phone has GPS or not
    private String GPS;
    // instance variables - replace the example below with your own
    private int x;

    // The constructor method

    public Mobile(String mobilephonetype, int mobilescreensize,
        int mobilememorycardcapacity,int mobilecameraresolution,
        String mobileGPS, String newserviceprovider) {
        this.phonetype =  mobilephonetype;
        this.screensize = mobilescreensize;