通过对象/类中的特定成员对对象数组进行排序
假设我有一个看起来像这样的类（get / set omited）：
class InfoClass{ String name; String place; double distance; } 我在我的主要活动中创建了一个类的数组，如下所示：
InfoClass[3] myInfoClass; myInfoClass[0].name = "venue one"; myInfoClass[0].place = "place one"; myInfoClass[0].distance = 11.23234; myInfoClass[1].name = "venue two"; myInfoClass[1].place = "place two"; myInfoClass[1].distance = 9.2345643; myInfoClass[2].name = "venue three"; myInfoClass[2].place = "place three"; myInfoClass[2].distance = 5.23432;
我如何对我的数组（myInfoClass []）进行排序，以便它由距离成员排序？ 即在上面的例子中，数组会被反转，因为元素[2]的距离最小，元素[0]的距离最大？
是否有一些function可以添加到我的class级来执行此操作或其他方式？
修改你的类并实现Comparable接口如果你不想使用Comparator ，那么默认情况下你想要为你的对象的array/collection提供排序然后去Comparable
class InfoClass implements Comparable { String name; String place; double distance; @Override public int compareTo(InfoClass o) { return new Double(this.distance).compareTo(new Double(o.distance)); }
然后你可以对它们进行排序
Arrays.sort(myInfoClass)
这应该工作..
public static void main(String[] args){ InfoClass[] dd = new InfoClass[3]; Arrays.sort(dd, new Comparator(){ @Override public int compare(InfoClass arg0, InfoClass arg1) { // TODO Auto-generated method stub if(arg0.distance == arg1.distance){ return 0; }else if(arg0.distance < arg1.distance){ return -1; }else{ return 1; } } }); }
您可以将Arrays.Sort与自定义比较器一起使用，如下所示：
Arrays.Sort(myInfoClass, new Comparator() { @Override public int compare(InfoClass o1, InfoClass o2){ if (o1==null && o2==null) return 0; if (o1 == null) return -1; if (o2 == null) return 1; return o1.distance.compareTo(o2.distance); } });
编辑： null检查胜利。
使用java.util.Arrays.sort()并指定您自己的Comparator ：
InfoClass[] myInfoClass = new InfoClass[3]; myInfoClass[0] = new InfoClass(); myInfoClass[1] = new InfoClass(); myInfoClass[2] = new InfoClass(); myInfoClass[0].name = "venue one"; myInfoClass[0].place = "place one"; myInfoClass[0].distance = 11.23234; myInfoClass[1].name = "venue two"; myInfoClass[1].place = "place two"; myInfoClass[1].distance = 9.2345643; myInfoClass[2].name = "venue three"; myInfoClass[2].place = "place three"; myInfoClass[2].distance = 5.23432; Arrays.sort(myInfoClass, new Comparator() { public int compare(InfoClass o1, InfoClass o2) { if (o1.distance == o2.distance) { return 0; } else if (o1.distance < o2.distance) { return -1; } return 1; } });
Arrays.sort(myInfoClass, new Comparator() { @Override public int compare(InfoClass o1, InfoClass o2) { return Double.valueOf(o1.distance).compareTo(o2.distance); } });
将数组转换为ArrayList，然后使用Collection.sort方法对ArrayList进行排序。
还按降序排序
Arrays.sort（aStudents，Collections.reverseOrder（））;
内部集合定义方法调用
`public static Comparator reverseOrder() { return (Comparator ) REVERSE_ORDER; }
public int compare（Comparable c1，Comparable c2）{return c2.compareTo（c1）; }`
希望，这个例子将帮助您根据各种字段 对类对象进行排序
import java.util.*; import java.lang.*; import java.io.*; public class Main { public static void main ( String [] args) throws IOException { Employee empList[] = new Employee [4]; empList[0] = new Employee (8,"Kiran","Developer",15000); empList[1] = new Employee (18,"Krishna","DBA",35000); empList[2] = new Employee (3,"Pradeep","Tester",25000); empList[3] = new Employee (7,"Mithun","Admin",20000); Arrays.sort(empList); System.out.println("\nAfter Sorting Base On ID"); for (Employee emp : empList) System.out.println(emp); Arrays.sort( empList , new EmployeeByDept() ); System.out.println("\nAfter Sorting Base On Department"); for (Employee emp : empList) System.out.println(emp); Arrays.sort( empList , new EmployeeByName() ); System.out.println("\nAfter Sorting Base On Name"); for (Employee emp : empList) System.out.println(emp); Arrays.sort( empList , new EmployeeBySalary() ); System.out.println("\nAfter Sorting Base On Salary"); for (Employee emp : empList) System.out.println(emp); } } class EmployeeByDept implements Comparator { //compare() is mathod of Comparable Interface // Use When we want to sort on other field like Department @Override public int compare(Employee emp1, Employee emp2) { return emp1.getDept().compareTo(emp2.getDept()); } } class EmployeeByName implements Comparator { //compare() is mathod of Comparable Interface // Use When we want to sort on other field like Department @Override public int compare(Employee emp1, Employee emp2) { return emp1.getName().compareTo(emp2.getName() ); } } class EmployeeBySalary implements Comparator { //compare() is mathod of Comparable Interface // Use When we want to sort on other field like Department @Override public int compare(Employee emp1, Employee emp2) { return ( emp1.getSalary() - emp2.getSalary()); } } class Employee implements Comparable { int $id ; String $name ; String $dept ; int $salary ; public Employee(int id , String name , String dept , int salary) { this.$id = id; this.$name = name ; this.$dept = dept ; this.$salary = salary ; } public int getID () { return this.$id ; } public String getName () { return this.$name ; } public String getDept () { return this.$dept ; } public int getSalary () { return this.$salary ; } public String toString() { return "[ " + "ID :: " + $id + " Name :: " + $name + " Department :: " + $dept + " Salary :: " + $salary + " ]"; } //compareTo() is mathod of Comparable Interface //Use when you want natural sorting base on ID , Salary @Override public int compareTo(Employee emp) { return (this.$id - emp.$id); } }