声明数组：

int[] a;

int a[];

两种方式。一般选择第一种，比较一目了然。

初始化,必须指定长度：

int[] a = new int[10];

int[] a = {1,2,3};

初始化：

1. package com.zjf;
2.  
3. import java.util.Arrays;
4.  
5. import com.zjf.spring.mybatis.model.Person;
6.  
7. public class Test {
8.  
9.    public static void main(String[] args) {
10.       //定义数组
11.       int[] a = new int[3];
12.       //默认初始化 打印查看为0
13.       System.out.println(Arrays.toString(a));
14.       //也可以存储对象
15.       Person[] p = new Person[2];
16.       //默认初始化为null
17.       System.out.println(Arrays.toString(p));
18.  
19.     }
20. }

结果：

[0, 0, 0]

[null, null]

数组拷贝

两种方式。

1. package com.zjf;
2. import java.util.Arrays;
3. public class Test {
4.    public static void main(String[] args) {
5.       int[] a = {0,1,2,3,4,5,6,7,8,9};
6.       int[] b = Arrays.copyOf(a, a.length);
7.       int[] c = new int[a.length];
8.       System.arraycopy(a, 0, c, 0, a.length);
9.       System.out.println(Arrays.toString(b));
10.       System.out.println(Arrays.toString(c));
11.     }
12. }

结果：

[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]

[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]

数组排序：

1. package com.zjf;
2. import java.util.Arrays;
3. import com.zjf.spring.mybatis.model.Person;
4. public class Test {
5.    public static void main(String[] args) {
6.       int[] a = {0,6,2,8,4,5,1,7,3,9};
7.       Arrays.sort(a);
8.       System.out.println(Arrays.toString(a));
9.       Person p1 = new Person(2,"zjf",29,"beiing");
10.       Person p2 = new Person(1,"xhj",29,"beiing");
11.       Person[] p = {p1,p2};
12.       Arrays.sort(p);
13.       System.out.println(Arrays.toString(p));
14.     }
15. }

结果：

[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]

Exception in thread "main" java.lang.ClassCastException: com.zjf.spring.mybatis.model.Person cannot be cast to java.lang.Comparable

    at java.util.ComparableTimSort.countRunAndMakeAscending(Unknown Source)

    at java.util.ComparableTimSort.sort(Unknown Source)

    at java.util.ComparableTimSort.sort(Unknown Source)

    at java.util.Arrays.sort(Unknown Source)

    at com.zjf.Test.main(Test.java:13)

1. package com.zjf;
2.  
3. import java.util.Arrays;
4. import java.util.Comparator;
5.  
6. import com.zjf.spring.mybatis.model.Person;
7.  
8. public class Test {
9.    public static void main(String[] args) {
10.       int[] a = { 0, 6, 2, 8, 4, 5, 1, 7, 3, 9 };
11.       Arrays.sort(a);
12.       System.out.println(Arrays.toString(a));
13.       Person p1 = new Person(2, "zjf", 29, "beiing");
14.       Person p2 = new Person(1, "xhj", 29, "beiing");
15.       Person[] p = { p1, p2 };
16.       Arrays.sort(p, new Comparator<Person>() {
17.          public int compare(Person o1, Person o2) {
18.             return o1.getId().compareTo(o2.getId());
19.          }
20.       });
21.       System.out.println(Arrays.toString(p));
22.    }
23. }

结果：

[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]

[id:1,name:xhj, id:2,name:zjf]

注：Arrays.sort使用的是快速排序算法。

Arrays的API：

原文：http://www.cnblogs.com/xiaolang8762400/p/7041233.html