Simple token manager for android

TokenManager.java

public class TokenManager {

    private static final  String TAG = TokenManager.class.getName();

    private static TokenManager instance;

    private String token;

    private TokenManager() {
        token = "";
    }

    /**
     * Init manager of Token
     */
    public static void init() {
        if(null==instance) {
            instance = new TokenManager();
        }
    }

    public static TokenManager getInstance() {
        return instance;
    }

    /**
     * Update value of TOKEN.
     * @param token token
     */
    public void setToken(String token) {
        this.token = token;
    }

    /**
     * Retieve current token
     *
     * @return Token
     */
    public String getToken(){
        return token;
    }

    /**
     * Indicate if we have a token
     *
     * @return true / false
     */
    boolean hasToken(){
        Log.d(TAG,"TOKEN : "+token);
        return null!=token && !"".equals(instance.token);
    }

    /**
     * Remove current token
     */
    void clearToken(){
        token = null;
    }
}