package day02;
import java.util.Arrays;
/*
數組：
固定長度
相同類型
有序的
*/
public class Demo05 {
public static void main(String[] args) {
//聲明一個數組，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); //長度
//數組的遍歷
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);
}
//取數組中的最大值/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("最大值為：" + max);
System.out.println("最小值為：" + min);
//冒泡排序
//交換兩個元素
/*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++) { //外層控制比較的趟數
for (int j = 0; j < nums.length - i - 1; j++) { //內層控制比較的趟數
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 數組轉字符串的方法
//聲明一個數組，并初始化（靜態(tài)初始化：聲明的同事賦值）
int[] id1s={1001,1002,1003,1004};
//動態(tài)初始化：聲明的時候不賦值
int[] id2s = new int[5];
for (int i=0;i<5;i++){
id2s[i] = i+1; //給數組里面的元素賦值
}
System.out.println(Arrays.toString(id2s));
System.out.println(id2s); //內存地址：【I@133314b】
//數組的默認值，對應類型的值
float[] fs = new float[5];
for (float f :fs){
System.out.println("數組沒有賦值時，有默認值，默認值為：" + f);
}
//非基本類型，默認值為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);
//非基本類型：類、數組、接口
//Demo05 是一個類，可以作為類型來使用
Demo05[] dd =new Demo05[3];
System.out.println(dd[0]);
}
}
ic class Demo06 {
public static void main(String[] args) {
//學號、分數
//4*2（長度固定）4行2列
int[][] cs = new int [][]{{1001,90},{1002,100},{1003,99},{1004,86}};
System.out.println("學號：" + cs[0][0] + "分數：" +cs[0][1]);
System.out.println("學號：" + cs[3][0] +"分數：" + cs[3][1]);
//遍歷數組
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 遍歷
for (int[] c:cs){
for (int i:c){
System.out.print(i+" ");
}
System.out.println();
}
System.out.println("=========================");
/*
練習：創(chuàng)建一個二維數組，數組中存放3個人的信息，每個人包括：姓名、年齡、身高、體重
3*4
遍歷數組，每個人的信息打印一行，用\t分隔開
idea 為定義的變量名
*/
//老師解法
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("============================");
//自己解法
String [][] idea = new String[][] {{"fan","18","160","60kg"},{"wang","18","155","50kg"},{"li","15","166","55kg"}};
for (int i=0;i<idea.length;i++){
for (int j=0;j<idea[i].length;j++){
System.out.print(idea[i][j] + " ");
}
System.out.println();
}
}
}
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