/*
数组:
固定长度
相同类型
有序的
*/
public class Demo05 {
public static void main(String[] args) {
//声明一个数组,并初始化
int[] ids = {1001, 1002, 1003, 1004};
System.out.println(ids[0]);
System.out.println(ids[3]);
//System.out.println(ids[4]);//
String[] names = {"aaa", "bbb", "ccc", "ddd"};
System.out.println(names.length); //长度
//数组的遍历
for (int i = 0; i < names.length; i++) {
System.out.println("hello," + names[i]);
}
System.out.println("==========================");
//foreach
for (String name : names) {
System.out.println("hello," + name);
}
//取数组中的最大值/最小值
int[] nums = {10, 6, 10, 8, 100, 70, 60, 30, 102};
int max = nums[0];
int min = nums[0];
for (int i = 1; i < nums.length; i++) {
if (nums[i] > max) {
max = nums[i];
}
if (nums[i] < min) {
min = nums[i];
}
}
System.out.println("最大值为:" + max);
System.out.println("最小值为:" + min);
//冒泡排序
//交换两个元素
/*int temp = a;
int a = b;
int b = temp;
//a,b=b,a */
System.out.println("排序前:" + Arrays.toString(nums));
for (int i = 0; i < nums.length; i++) { //外层控制比较的趟数
for (int j = 0; j < nums.length - i - 1; j++) { //内层控制比较的趟数
if (nums[j] < nums[j + 1]) {
int temp = nums[j];
nums[j] = nums[j + 1];
nums[j + 1] = temp;
}
}
}
System.out.println("排序后" + Arrays.toString(nums)); // Arrays.toString 数组转字符串的方法
//声明一个数组,并初始化(静态初始化:声明的同事赋值)
int[] id1s={1001,1002,1003,1004};
//动态初始化:声明的时候不赋值
int[] id2s = new int[5];
for (int i=0;i<5;i++){
id2s[i] = i+1; //给数组里面的元素赋值
}
System.out.println(Arrays.toString(id2s));
System.out.println(id2s); //内存地址:【I@133314b】
//数组的默认值,对应类型的值
float[] fs = new float[5];
for (float f :fs){
System.out.println("数组没有赋值时,有默认值,默认值为:" + f);
}
//非基本类型,默认值为null
String[] ss = new String[6];
System.out.println(ss[0]);
char[] cs = new char[6];
System.out.println((int)cs[0]);
System.out.println("===" + cs[0] + "===");
char s = ' ';
System.out.println((int)s);
//非基本类型:类、数组、接口
//Demo05 是一个类,可以作为类型来使用
Demo05[] dd =new Demo05[3];
System.out.println(dd[0]);
}
}
ic class Demo06 {
public static void main(String[] args) {
//学号、分数
//4*2(长度固定)4行2列
int[][] cs = new int [][]{{1001,90},{1002,100},{1003,99},{1004,86}};
System.out.println("学号:" + cs[0][0] + "分数:" +cs[0][1]);
System.out.println("学号:" + cs[3][0] +"分数:" + cs[3][1]);
//遍历数组
for (int i=0;i<cs.length;i++){
for (int j=0;j<cs[i].length;j++){
System.out.print(cs[i][j] + " ");
}
System.out.println();
}
//foreach 遍历
for (int[] c:cs){
for (int i:c){
System.out.print(i+" ");
}
System.out.println();
}
System.out.println("=========================");
/*
练习:创建一个二维数组,数组中存放3个人的信息,每个人包括:姓名、年龄、身高、体重
3*4
遍历数组,每个人的信息打印一行,用\t分隔开
idea 为定义的变量名
*/
//老师解法
String[][] infos = new String[][]{{"fan","18","160","60kg"},{"wang","18","155","50kg"},{"li","15","166","55kg"}};
for (String[] info:infos){
for (String i : info){
System.out.print(i + "\t");
}
System.out.println();
}
System.out.println("============================");
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