下标从0开始; 访问招标元素会抛出异常;
•
声明 int [] a or int a []
•
初始化 a = new int[5]
•
声明加初始化 int [] arr = new int [5]; int [] arr = new int [] {1,2,3}; //注意右边中括号里不能加长度，否则失败。 int [] arr = {1,2,3} 简单
•
遍历
for(int i =0; i<arr.length; i++)
{
System.out.println( arr[i] );
}
for(int[] i :crr)
for(int j:i)
System.out.println(j);
数组倒置类
class Demo7
{
public static void main(String[] args)
{
int [] arr = {12,56,25,89,73};
arrInverse(arr);
printArr(arr);
}
private static void arrInverse(int[] a)
{
int len = a.length;
for(int i = 0;i<len/2;i++)
{
swap(a,i,len-1-i);
}
}
public static void swap(int[] a,int l,int r)
{
int temp=a[l];
a[l]=a[r];
a[r]=temp;
}
private static void printArr(int [] a)
{
System.out.print("[");
for(int i = 0; i < a.length; i++)
{
if(i==a.length-1)
System.out.print(a[i]+"]");
else
System.out.print(a[i]+",");
}
}
}
二维数组
•
声明 int[][] arr1; int [][] arr2; int arr3[][]; int arr4 [][];
•
初始化 a = new int[2][4]//后面不能加{} arr = new int[][]{{1,2},{2},{3}}; int[][] arr = {{1,2},{2},{3}};
•
{{1,2},{2},{3}}只能在初始化的时候用,即使从未赋过值
int arr4 [][];
arr4 = {{2,3},{4,6},{7},{12,45,67},{100}};//报错,只能初始化时用
//crr = {{2,3},{4,6},{7},{12,45,67},{100}}; //报错
int[][] crr = new int[][] {{2,3},{4,6},{7},{12,45,67},{100}};
int[][] vrr = {{2,3},{4,6},{7},{12,45,67},{100}}; //常用,常用,常用
crr = new int[][] {{2,3},{4,6},{7},{12,45,67},{100}};•
声明加初始化
`` 简单
•
遍历
for(int i =0; i<arr.length; i++)
{
System.out.println( arr[i] );
}数组没有length()方法,但是有length属性.
评论区