单例模式
2020-06-10 本文已影响0人
寂静的春天1988
饿汉式
public class Student {
private Student() {
}
private static Student s = new Student();
public static Student getStudent() {
return s;
}
public static void main(String[] args) {
Student s1=Student.getStudent();
Student s2=Student.getStudent();
System.out.println(s1==s2);
}
}
懒汉式:使用同步方法
public class Student {
private Student() {
}
private static Student s = null;
public synchronized static Student getStudent() {
if(s==null) {
s=new Student();
}
return s;
}
public static void main(String[] args) {
Student s1=Student.getStudent();
Student s2=Student.getStudent();
System.out.println(s1==s2);
}
}
懒汉式：使用同步代码块
public class Student {
private Student() {
}
private static Student s = null;
public static Student getStudent() {
if(s==null) {
synchronized(Student.class) {
if(s==null) {
s=new Student();
}
}
}
return s;
}
public static void main(String[] args) {
Student s1=Student.getStudent();
Student s2=Student.getStudent();
System.out.println(s1==s2);
}
}
开发中一般使用：饿汉式
