Java中的数组排序
Java中的数组排序，一般是利用Arrays.sort(),这个方法是经过优化的快速排序。在Arrays种有多中形式的重载，在这里就不一一列举了。
数组排序的种类：
1.非降序排序， 非升序排序（就排序后数组元素排列的结果而言）
2.基本类型数据的排序，类类型数据的排序（就排序的对象而言）
排序示例：
int型数组的非降序排序：
1 package sort; 2 3 import java.util.Arrays; 4 5 public class Main { 6 public static void displayArray(int[] array) { 7 for (int i: array) { 8 System.out.print(i + " "); 9 } 10 System.out.println(); 11 } 12 13 public static void main(String[] args) { 14 int[] arr = new int[]{43, 84, 3, 8, 4, 7, 3, 75, 82, 748, 35}; 15 16 System.out.println("排序前:"); 17 displayArray(arr); 18 19 Arrays.sort(arr); 20 21 System.out.println("排序后:"); 22 displayArray(arr); 23 } 24 }
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运行结果如下:
int型数组的非升序排序：
1 package sort; 2 3 import java.util.Arrays; 4 import java.util.Comparator; 5 6 public class Main { 7 public static void displayArray(Integer[] array) { 8 for (int i: array) { 9 System.out.print(i + " "); 10 } 11 System.out.println(); 12 } 13 14 public static void main(String[] args) { 15 Integer[] arr = new Integer[]{43, 84, 3, 8, 4, 7, 3, 75, 82, 748, 35}; 16 17 System.out.println("排序前:"); 18 displayArray(arr); 19 20 Arrays.sort(arr, new JX()); 21 22 System.out.println("排序后:"); 23 displayArray(arr); 24 } 25 } 26 27 class JX implements Comparator<Integer> { 28 @Override 29 public int compare(Integer o1, Integer o2) { 30 if (o1 <= o2) { 31 return 1; 32 } 33 return -1; 34 } 35 }
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运行结果如下：
类类型的非降序排序：
1 package sort; 2 3 import java.util.Arrays; 4 5 public class Main { 6 public static void displayArray(Student[] student) { 7 for (Student s : student) { 8 System.out.println(s); 9 } 10 } 11 12 public static void main(String[] args) { 13 Student[] s = new Student[5]; 14 s[0] = new Student("wwww", 20, 2.34); 15 s[1] = new Student("kkkk", 2, 2.34); 16 s[2] = new Student("pppp", 25, 3.34); 17 s[3] = new Student("hhhh", 12, 4.34); 18 s[4] = new Student("jjjj", 10, 5.34); 19 20 System.out.println("排序前:"); 21 displayArray(s); 22 23 Arrays.sort(s); 24 25 System.out.println("排序后:"); 26 displayArray(s); 27 } 28 } 29 30 /* 31 * 根据年龄进行非降序排序 32 */ 33 class Student implements Comparable<Student> { 34 private String name; 35 private int age; 36 private double height; 37 38 public Student(String name, int age, double height) { 39 this.name = name; 40 this.age = age; 41 this.height = height; 42 } 43 44 @Override 45 public int compareTo(Student o) { 46 if (this.age <= o.age) { 47 return -1; 48 } 49 return 1; 50 } 51 52 public String toString() { 53 return "Name: " + name + " Age: " + age + " Height: " + height; 54 } 55 }
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运行结果如下：
类类型的非升序排序：
1 package sort; 2 3 import java.util.Arrays; 4 5 public class Main { 6 public static void displayArray(Student[] student) { 7 for (Student s : student) { 8 System.out.println(s); 9 } 10 } 11 12 public static void main(String[] args) { 13 Student[] s = new Student[5]; 14 s[0] = new Student("wwww", 20, 2.34); 15 s[1] = new Student("kkkk", 2, 2.34); 16 s[2] = new Student("pppp", 25, 3.34); 17 s[3] = new Student("hhhh", 12, 4.34); 18 s[4] = new Student("jjjj", 10, 5.34); 19 20 System.out.println("排序前:"); 21 displayArray(s); 22 23 Arrays.sort(s); 24 25 System.out.println("排序后:"); 26 displayArray(s); 27 } 28 } 29 30 /* 31 * 根据年龄进行非升序排序 32 */ 33 class Student implements Comparable<Student> { 34 private String name; 35 private int age; 36 private double height; 37 38 public Student(String name, int age, double height) { 39 this.name = name; 40 this.age = age; 41 this.height = height; 42 } 43 44 @Override 45 public int compareTo(Student o) { 46 if (this.age <= o.age) { 47 return 1; 48 } 49 return -1; 50 } 51 52 public String toString() { 53 return "Name: " + name + " Age: " + age + " Height: " + height; 54 } 55 }
View Code
运行结果如下:
根据指定属性对类类型数组排序：
1 package sort; 2 3 import java.util.Arrays; 4 import java.util.Comparator; 5 6 public class Main { 7 public static void displayArray(Student[] student) { 8 for (Student s : student) { 9 System.out.println(s); 10 } 11 } 12 13 public static void main(String[] args) { 14 Student[] s = new Student[5]; 15 s[0] = new Student("wwww", 20, 2.34); 16 s[1] = new Student("kkkk", 2, 2.34); 17 s[2] = new Student("pppp", 25, 3.34); 18 s[3] = new Student("hhhh", 12, 4.34); 19 s[4] = new Student("jjjj", 10, 5.34); 20 /* 21 System.out.println("排序前:"); 22 displayArray(s); 23 */ 24 System.out.println("按age进行非降序排序"); 25 Arrays.sort(s, new SortByAge()); 26 displayArray(s); 27 28 System.out.println("按height进行非升序排序"); 29 Arrays.sort(s, new SortByHeight()); 30 displayArray(s); 31 } 32 } 33 34 class Student { 35 private String name; 36 private int age; 37 private double height; 38 39 public Student(String name, int age, double height) { 40 this.name = name; 41 this.age = age; 42 this.height = height; 43 } 44 45 public String toString() { 46 return "Name: " + name + " Age: " + age + " Height: " + height; 47 } 48 49 public int getAge() { 50 return age; 51 } 52 53 public double getHeight() { 54 return height; 55 } 56 } 57 58 /* 59 * 按age进行非降序排序 60 */ 61 class SortByAge implements Comparator<Student> { 62 @Override 63 public int compare(Student o1, Student o2) { 64 if (o1.getAge() <= o2.getAge()) { 65 return -1; 66 } 67 return 1; 68 } 69 } 70 71 /* 72 * 按height进行非升序排序 73 */ 74 class SortByHeight implements Comparator<Student> { 75 @Override 76 public int compare(Student o1, Student o2) { 77 if (o1.getHeight() - o2.getHeight() < 0.01) { 78 return 1; 79 } 80 return -1; 81 } 82 83 }
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运行结果如下：
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