package Lx;
import sun.security.util.Length;
import java.util.Arrays;
import java.util.logging.Level;
/**
- Java in the array: the array is a reference data type;
- An array is used to store a series of data elements of the same type;
- The format of the array;
-
格式1:数据类型[] 数组名=new 数据类型[数组长度];
* Note: 1: Direct output array name will output the address output memory, if you need the output contents of the array, you need to be achieved through Arrays.toString (array name)
-
2:如果不输入内容 程序会输出系统默认类型值:如:int[]:0:double[]:0.0:boolean[]:false;String[]:null;
-
3:数组定义时必须指定长度
-
格式2:数据类型[] 数组名 = {值1,值.....值n};
-
格式3:数据类型[] 数组名 = new int[]{值1,值.....值n};
*/
public class ArrayDemo {
public static void main(String[] args) {
int[] sry = new int[3];
double[] ds = new double[5];
boolean[] bs = new boolean[3];
String[] st = new String[3];
System.out.println(sry);//输出的是地址;[I@140e19d
System.out.println(ds);//[D@17327b6
System.out.println(bs);//[Z@14ae5a5
//打印数组中的内容;Arrays.toString(相同类型的数组名)
System.out.println(Arrays.toString(sry));//[0, 0, 0]
System.out.println(Arrays.toString(ds));//[0.0, 0.0, 0.0, 0.0, 0.0]
System.out.println(Arrays.toString(bs));//[false, false, false]
System.out.println(Arrays.toString(st));//[null, null, null]
String[] names = {"张三","李四","王五","张鑫"};
System.out.println(Arrays.toString(names));//[张三, 李四, 王五]
//使用数组: 获取数组的长度:数组名。length
System.out.println(names.length);//4
//获取数组中元素:格式:数组名(下标 [位置])
System.out.println(names[2]);//王五
//获取数组最后一个元素,数组名[length-1]
System.out.println(names[names.length-1]);//张鑫
//修改数组中的某个位置的元素:数组名[位置]=值
names[1]= "李杰";
//重新读取 输出要加Arrays.toString(数组名)
System.out.println(Arrays.toString(names));//[张三, 李杰, 王五, 张鑫]
//把数组变成字符串
char[] cs = new char[]{'我','在','吃','饭'};
String names1 = new String(cs,0,cs.length);
System.out.println(names1);//变成了:“我在吃饭”
//输出这个字符串;单纯只看数组内容的 用下面这个
String ns = Arrays.toString(names);//[张三, 李杰, 王五, 张鑫]
//遍历数组;核心原理 ,逐个使用下标,将数组中的元素取出.从0开始到length-1
for (int i=0;i<names.length;i++){
System.out.println(names[i]);//张三 变成竖着一排
//李杰
//王五
//张鑫
}
//遍历数组;给新建的数组赋值;如果是看数组里面单个内容用遍历
int[] a = new int[4];
System.out.println(Arrays.toString(a));//遍历前[0, 0, 0, 0]
for (int i = 0; i< a.length;i++){
a[i] = i*10;
}
System.out.println(Arrays.toString(a));//遍历后[0, 10, 20, 30]
}
}