public static void main(String[] args) {
//数组遍历逻辑
int [] array = new int[10];
for (int i = 0; i< array.length;i++){
array[i] = (int)(Math.random()*10);
System.out.println(array[i]);
}
System.out.println("-------------------");
//遍历数组中的内容
for (int i = 0;i< array.length;i++){
System.out.println(array[i]);
}
System.out.println("-------------------");
//-- 输出的只有偶数部分 0 2 4 6 8
for (int i = 0;i< array.length;i+=2){
System.out.println(array[i]);
}
System.out.println("-------------------");
//-- 输出的只有奇数部分 1 3 5 7 9
for (int i = 1; i5){
System.out.println(array[i]);
}
}
System.out.println("-------------------");
// 前三个
int count = 0;
for (int i = 0;i< array.length;i++){
System.out.println(array[i]);
count++;
System.out.println(count);
if (count == 3){
break;
}
}
System.out.println("-----------------------------------");
//要求倒叙打印数组
for (int i = array.length-1;i>=0;i--){
System.out.println(array[i]);
}
System.out.println("-------------------");
//求所有元素的和
int sum = 0;
for (int i = 0;i< array.length;i++){
sum+=array[i];
}
System.out.println(sum);
System.out.println("-------------------");
//求最小值 假设数组中的第一个元素就是最小值
int min = array[0];
for (int i = 0; i < array.length; i++) {
if (array[i] < min) {
min = array[i];
}
}
System.out.println(min);
}
2.定义一个数组{1,3,4,2,6,2,6,2,8,2,6},要求输出结果是不重复的数
public static void main(String[] args) {
int[] oldArr = {1,3,4,2,6,2,6,2,8,2,6};
int[] tempArr = new int[6];
boolean flag;
int num = 0;//索引
for (int i = 0; i < oldArr.length; i++) {
flag = false;
for (int j = 0; j< tempArr.length; j++) {
//验证重复
if (oldArr[i] == tempArr[j]) {
flag = true;
break;
}
}
if(flag){
continue;
}
tempArr[num++] = oldArr[i];
}
System.out.println(Arrays.toString(tempArr));
}
3.查找数组a中的最大值、最小值,并打印输出它们的下标位置;
public static void main(String[] args) {
//3、查找数组a中的最大值、最小值,并打印输出它们的下标位置;
int[] a = {1, 9, 2, 5, 4, 8, 3, 6, 7, 10, 8};
int max = 0;
int min = 0;
int maxIndex = 0; //最大值索引
int minIndex = 0; //最小值索引
max = a[0];
min = a[0];
for (int i = 0; i < a.length; i++) {
if (a[i] >= max) {
max = a[i];
maxIndex = i;
} else if (a[i] <= min) {
min = a[i];
minIndex = i;
}
}
System.out.println("最大值为"+max+"下标为"+maxIndex);
System.out.println("最小值为"+min+"下标为"+minIndex);
}
4.定义一个数组来存储12个学生的成绩{72,89,65,58,87,91,53,82,71,93,76,68},计算并输出学生的平均成绩(保留小数点后两位。)
public static void main(String[] args) {
int[] score = {72,89,65,58,87,91,53,82,71,93,76,68};
int sum = 0;
for (int i = 0; i
5.统计数组{20,45,78,34,16,3,99,56}中大于50的有多少个、小于50的有多少个并打印输出。
public static void main(String[] args) {
int[] a = {20,45,78,34,16,3,99,56};
int max = 0;//大于50的
int min = 0;//小于50的
for (int i = 0;i< a.length;i++){
if (a[i]>50){
max++;
}
else if (a[i]<50){
min++;
}
}
System.out.println("数组{20,45,78,34,16,3,99,56}中,大于50的数有:"+max+"个,小于50的数有:"+min+"个。");
}
6.在数组{4,5,6,2,3,1,9,8,7,10,12,14,15}中查找元素(先打印输出所有元素,输入一个数,如果找到了则打印输出其位置,没有找到则提示没有找到)
public static void main(String[] args) {
int[] a = {4,5,6,2,3,1,9,8,7,10,12,14,15};
Scanner sc = new Scanner(System.in);
System.out.println("请输入查询的数:");
int j = sc.nextInt();
boolean isflag = false;
for (int i = 0; i< a.length; i++){
if (a[i] == j){
System.out.println(j+"的位置是"+i);
isflag = true;
break;
}
}
if (!isflag) {
System.out.println("查无此数");
}
}
7.声明一个int型的数组,循环随机生成13个1到13之间随机数放入到此数组中去,再循环输出
public static void main(String[] args) {
int[] arr = new int[13];
for (int i = 0;i< arr.length;i++){
arr[i] = (int)(Math.random()*12);
System.out.println(arr[i]);
}
}
8.循环输入5个整数放入到一个整形的数组中,然后再循环数组中的数,统计有多少个数大于0
public static void main(String[] args) {
int[] arr = new int[5];
Scanner sc = new Scanner(System.in);
for (int i = 0; i< arr.length;i++){
System.out.println("请输入第" + (i+1) + "个数");
arr[i] = sc.nextInt();
int count = arr[i];
if (count > 0 ){
System.out.println(count);
}
}
}
9.声明一个char型的数组,在此数组的单元格中放入"我爱你"三个字符,然后使用循环将它反序输出。如"你爱我"
public static void main(String[] args){
char[] arr = {'我','爱','你'};
for (int i = 2; i>=0; i--){
System.out.println(arr[i]);
}
}
10.定义一个长度为1的字符串数组。循环输入1个姓名。然后再输入一个用户的姓名,检查数组中是否有这个人的姓名,并输出所在下标
public static void main(String[] args) {
char[] arr = new char[1];
Scanner sc = new Scanner(System.in);
System.out.println("请输入1个姓名");
char name = sc.next().charAt(0);
System.out.println("请再输入1个姓名");
char name1 = sc.next().charAt(0);
for (int i =0; i< arr.length; i++){
if (arr[i] == name && arr[i] == name1)
System.out.println(i);
}
}
11.给定两个数组a{1,2,3,4} b{5,6,7,8}将两个元素对应位置互换
public static void main(String[] args) {
//给定两个数组a{1,2,3,4} b{5,6,7,8}将两个元素对应位置互换\
System.out.println("只适用于两个长度相等的数组互换");
System.out.println("-------------------------");
int[] a = {1,2,3,4};
int[] b = {5,6,7,8,9,10};
int[] temp = a;
a = b;
b = temp;
System.out.println(Arrays.toString(a));
System.out.println(Arrays.toString(b));
}
12.随机生成26个字母,倒叙输出,并不能有重复项(冒泡算法)
public static void main(String[] args) {
char[] array = new char[26];
for (int i = 0; i< array.length; i++){
array[i] = (char)(Math.random()*26+65);
for (int j =0; j< array.length;j++){
if (array[i] == array[j] && i!= j ){
i--;
break;
}
}
}
for (int i = 0; i< array.length-1; i++){
boolean flag = false;
for (int j = 0; j
13.双色球
public static void main(String[] args) {
//双色球
//生成100期号码,每期号码有7个数
int[][] lottery = new int[100][7];
for (int i =0; i< lottery.length; i++){
int[] stage = lottery[i];//一期的数
for (int j =0; j< stage.length; j++){
if (j == 6){//第七个数是蓝球,所以索引-1是6
stage[j] = (int)(Math.random()*16)+1;//lan球取值范围是1-16
}
else{ //-- 红球 取值范围1-33
stage[j] = (int)(Math.random()*33)+1;
//-- 红球是不可以重复的。所以需要验证是否重复,j代表第i期的第j个球
//-- 用第j个球和0到j-1之间的所有球做比较
for (int k = 0; k< j; k++){
if (stage[k] == stage[j]){
j--;
break;
}
}
}
}
}
for (int i = 0; i < lottery.length; i++) {
//-- 想输出第几期,需要索引
System.out.print("第" + (i + 1) + "期号码:");//i是0所以+1输出第一期
int[] stage = lottery[i];
for (int j = 0; j < stage.length; j++) {
System.out.print(stage[j] + " ");
}
System.out.println();
}
//统计出现的次数 思路:用号码作为另外一个数组的下标,下标所对应空间记录该号码出现的次数
//统计红球 每个号码出现的次数
int[] redBall = new int[33];
//-- 统计蓝球 每个号码出现的次数
int[] blueBall = new int[16];
//遍历100期的
for (int i = 0; i< lottery.length; i++){
int[] stage = lottery[i];
for (int j = 0; j < stage.length; j++){
if (j == 6){//-- 蓝球的取值是1-16.索引的范围是0-15.关系是-1
int blue = stage[j];
blueBall[blue-1] = blueBall[blue-1]+1;
}
else {
int red = stage[j];
redBall[red - 1] = redBall[red - 1] + 1;
}
}
}
//输出红球出现的次数
for (int i = 0; i< redBall.length; i++){
System.out.println("第"+(i+1)+"次输出,红球的个数是"+redBall[i]);
}
//输出lan球出现的次数
for (int i = 0; i< blueBall.length; i++){
System.out.println("第"+(i+1)+"次输出,红球的个数是"+blueBall[i]);
}
//排序
int[][] blueBall2 = new int[16][2];
int[][] redBall2 = new int[33][2];
for (int i = 0; i< lottery.length; i++) {
int[] stage = lottery[i];
for (int j = 0; j < stage.length; j++) {
if (j == 6) {//-- 蓝球的取值是1-16.索引的范围是0-15.关系是-1
int blue = stage[j];
blueBall2[blue - 1][0] = blue;
blueBall2[blue - 1][1] = blueBall2[blue - 1][1] + 1;
} else {
int red = stage[j];
redBall2[red - 1][0] = red;
redBall2[red - 1][1] = redBall2[red - 1][1] + 1;
}
}
}
System.out.println("排序前蓝球次数:");
//lan球次数
for (int i = 0; i < blueBall2.length; i++) {
int[] ball_count = blueBall2[i];
System.out.println(Arrays.toString(ball_count));
}
System.out.println("排序前红球次数:");
for (int j = 0; j < redBall2.length; j++) {
int[] ball_count = redBall2[j];
System.out.println(Arrays.toString(ball_count));
}
//开始排序
for (int i = 0; i< blueBall2.length-1; i++){
for (int j = 0; j blueBall2[j+1][1]){
int[] temp = blueBall2[j];
blueBall2[j] = blueBall2[j+1];
blueBall2[j+1] = temp;
}
}
}
System.out.println("蓝球排序后:");
for (int i = 0; i < blueBall2.length; i++) {
int[] ball_count = blueBall2[i];
System.out.println(Arrays.toString(ball_count));
}
for (int i = 0; i< redBall2.length-1; i++){
for (int j = 0; j redBall2[j+1][1]){
int[] temp = redBall2[j];
redBall2[j] = redBall2[j+1];
redBall2[j+1] = temp;
}
}
}
System.out.println("红球排序后:");
for (int i = 0; i < redBall2.length; i++) {
int[] ball_count = redBall2[i];
System.out.println(Arrays.toString(ball_count));
}
}