java Singleton 사용하기

싱글톤 선언 및 싱글톤 메서드에 값 넣어주기

public class Method_Singleton {

	private static Method_Singleton instance; // 정적 필드, 인스턴스 생성
	
	//private 생성자
	private Method_Singleton() {}
	
	public static Method_Singleton getInstance(){
		
		if(instance == null) {
			instance = new Method_Singleton();
			
		}
		return instance;
		
	}
	
	// 값 넣어주기
	public int num_singleton = 0;
	
	public String str_singleton = "";
	
	public List<String> list_singleton = new ArrayList<>();
	
	public void test_singleton() {
		num_singleton = 10;
		
		str_singleton = "str_singleton";
		
		list_singleton.add("list1");
		list_singleton.add("list2");
		list_singleton.add("list3");
	}
	
	
	
	
}

 

메인 메서드에서 실행하기

public class Method_main {

	public static void main(String[] args) {
    
    	// Method 호출
		Method_Singleton.getInstance().test_singleton();
		
		
		int num1 =  Method_Singleton.getInstance().num_singleton;
		
		String str1 = Method_Singleton.getInstance().str_singleton; 
		
		List<String> list1 = Method_Singleton.getInstance().list_singleton;
		
		System.out.println("num_singleton : "+num1);
		System.out.println("str_singleton : "+str1);
		System.out.println("list_singleton : "+list1);
		
	}
}

 

<결과>

num_singleton : 10
str_singleton : str_singleton
list_singleton : [list1, list2, list3]