package Counter;
public class Counter {
private int counter;
private static Counter instance = null;
protected Counter() {
}
public static Counter getInstance() {
if (instance == null) {
instance = new Counter();
System.out.println("New instance created\n");
}
return instance;
}
public void incrementCounter() {
counter++;
}
public int getCounter() {
return (counter);
}
}
package Counter;
public class Singleton {
public static void main(String[] args) {
Counter counter1=Counter.getInstance();
counter1.incrementCounter();
counter1.incrementCounter();
System.out.println("Counter:"+counter1.getCounter());
Counter counter2=Counter.getInstance();
counter2.incrementCounter();
counter2.incrementCounter();
System.out.println("Counter:"+counter2.getCounter());
}
}
单例模式java实现