整型数组：
//静态初始化
int[] intArr = new int[]{1,2,3,4,5,6};
//简化版
int[] intArr = {1,2,3,4,5,6};
//动态初始化
int[] intArr = new int[6];
//初始化二维数组
int[][] intMatrix = {{1,2},{3,4},{5,6}};
int[][] intMatrix = new int[3][2];
//获取数组长度
int rowLength = intMatrix.length;//行数
int colLength = intMatrix[0].length;//第0行列数
字符串
//初始化
String str = "hello,world";
//字符串长度
System.out.println(str.length());
//遍历字符串
for(int i=0;i<str.length();i++){
char ch = str.charAt(i);
}
//字符转ASCII码
char a = 'a'
int a_ASCII = (int) a;
//截取子字符串
String Str = “hello,world”;
String subStr = str.substring(2,4)//out:"ll"
常用ASCII码
数字0-9 ：48~57. 26个大写字母：65~90. 26个小写字母：97~122.
