One way is by adopting the common currency(the Euro). I will let someone else give a second way.
Albania is not a member of the organisation known as the European Union. It is a European country, being part of the continent of Europe.
Yes, Malta is a member of the European Union from 2004.
The newest member of the European Union is Croatia, who joined on the 1st of July 2013. Before that, Romania and Bulgaria both joined in 2007, which is probably the answer you were looking for.
Nigeria is a country in west Africa. It is not a member of the European Union.
A country may not want to join the European Union because they seek neutrality, are doing fine on their own, or are displeased with the European Union (opposed of the idea or members or just displeased with the outcome [most important example is economic meltdown of the European Union]). EU has many laws that has to be adopted by the member countries. Member countries also may have to help other member countries in financial crisis. However, despite these reasons, almost all countries in Europe wish to join the European Union, either soon or in the near future.
Japan is not a member of the European Union.
Bosnia Herzegovina is not a member of the European Union.
Countries are members of the European Union, not people or trade unions. As Malta is one country that is a member of the European Union, then the amount of members of the European Union from Malta is one.
As of March 2017 - there are 28 member states in the European Union.
Ireland, Malta, Cyprus, Austria, Finland and Sweden are the 6 members of the European Union, that are not members of NATO.
Russia is not a member of the European Union, which has 28 nations. Not all European countries are members of it.
No African country is a member of the European Union. 28 of Europe's countries are members. See the related question below.
Neither Switzerland nor Australia are members of the European Union. Austria, which you may have meant, is a member of the European Union.
Albania is not a member of the organisation known as the European Union. It is a European country, being part of the continent of Europe.
Only countries are members of the European Union. Germany is one country that is a member, so it has one country, itself, as a member.
The European Commission has 28 members, one from each country that is a member of the European Union.
The European Union is an organisation that has countries as members. Microsoft is a company, not a country, so it is not a member of the European Union.