java集合Collections.sort()的方法应用

简单介绍集合工具类sort()的方法应用,简单类型排序和根据对象字段来排序.代码如下:

public class SomeTest {
	public static void main(String[] args) {
		SomeTest st = new SomeTest();
		List<String> list = new ArrayList<>();
		list.add("bu");
		list.add("cu");
		list.add("ca");
		list.add("a");
		Collections.sort(list);//简单排序
		System.out.println(list);
		//对象排序
		List<employee> strList = new ArrayList<>();
		employee e1 = st.new employee("bily", 10, 18000);
		employee e2 = st.new employee("fulosa", 10, 16000);
		employee e3 = st.new employee("aiwen", 10, 17000);
		employee e4 = st.new employee("cicy", 10, 13000);
		strList.add(e1);
		strList.add(e2);
		strList.add(e3);
		strList.add(e4);
		/**有几种自定义API,根据类型来选择*/
		strList.sort(Comparator.comparingDouble(employee::getSalary));//排序,根据工资
		System.out.println(strList.toString());
		strList.sort(Comparator.comparingDouble(employee::getSalary).reversed());//自定义排序逆序
		System.out.println(strList.toString());
		strList.sort(Comparator.comparing(employee::getName));//根据名字排序,调用String类型的比较方法
		System.out.println(strList.toString());
	}
	class employee{
		private String name;
		private int age;
		private double salary;
		public employee(String name,int age, double salary){
			this.name=name;
			this.age=age;
			this.salary=salary;
		}
		public String getName() {
			return name;
		}
		public void setName(String name) {
			this.name = name;
		}
		public int getAge() {
			return age;
		}
		public void setAge(int age) {
			this.age = age;
		}
		public double getSalary() {
			return salary;
		}
		public void setSalary(double salary) {
			this.salary = salary;
		}
		@Override
		public String toString() {
			return "employee [name=" + name + ", age=" + age + ", salary=" + salary + "]";
		}		
	}
}

结果输出:

[a, bu, ca, cu]
[employee [name=cicy, age=10, salary=13000.0], employee [name=fulosa, age=10, salary=16000.0], employee [name=aiwen, age=10, salary=17000.0], employee [name=bily, age=10, salary=18000.0]]
[employee [name=bily, age=10, salary=18000.0], employee [name=aiwen, age=10, salary=17000.0], employee [name=fulosa, age=10, salary=16000.0], employee [name=cicy, age=10, salary=13000.0]]
[employee [name=aiwen, age=10, salary=17000.0], employee [name=bily, age=10, salary=18000.0], employee [name=cicy, age=10, salary=13000.0], employee [name=fulosa, age=10, salary=16000.0]]