package top.iyunsir.array;
public class ArrayDemo01 {
//变量的类型 变量的名字 = 变量的值;
//数组类型
public static void main(String[] args) {
int[]nums; //1.声明一个数组
nums = new int[10]; //2.创建一个数组
// int[]nums2 = new int[10];
//3.给数组元素中赋值
nums[0] = 1;
nums[1] = 2;
nums[2] = 3;
nums[3] = 4;
nums[4] = 5;
nums[5] = 6;
nums[6] = 7;
nums[7] = 8;
nums[8] = 9;
nums[9] = 10;
//计算所有元素的和
int sum = 0;
//获取数组长度: arrays.length
for (int i = 0; i < nums.length; i++) {
sum = sum + nums[i];
}
System.out.println("总和为: " +sum);
}
}
package top.iyunsir.array;
public class ArrayDemo02 {
public static void main(String[] args) {
//静态初始化: 创建 + 赋值
int[] a = {1,2,3,4,5,6,7,8};
// System.out.println(a[0]);
for (int i = 0; i < a.length; i++) {
System.out.println(a[i]);
}
//动态初始化: 包含默认初始化
// int[] b = new int[10];
// b[0] = 10;
// b[1] = 10;
// System.out.println(b[0]);
// System.out.println(b[1]);
// System.out.println(b[3]);
// System.out.println(b[4]);
}
}
package top.iyunsir.array;
public class ArrayDemo03 {
public static void main(String[] args) {
int[] arrays = {1,2,3,4,5};
//打印全部的数组元素
for (int i = 0; i < arrays.length; i++) {
System.out.println(arrays[i]);
}
System.out.println("==============");
//计算所有元素的和
int sum = 0;
for (int i = 0; i < arrays.length; i++) {
sum = sum + arrays[i];//sum+ = arrays[i]
}
System.out.println("sum="+sum);
System.out.println("==============");
//查找最大元素
int max = arrays[0];
for (int i = 1; i < arrays.length; i++) {
if (arrays[i]>max){
max = arrays[i];
}
}
System.out.println("max="+max);
}
}
package top.iyunsir.array;
public class ArraysDemo04 {
public static void main(String[] args) {
int[] arrays = {1,2,3,4,5};
//JDK1.5, 没有下标
// for (int array : arrays) {
// System.out.println(array);
// }
// printArray(arrays);
final int[] reverse = reverse(arrays);
// System.out.println(reverse);
printArray(reverse);
}
//打印数组元素
public static void printArray(int[] arrays) {
for (int i = 0; i < arrays.length ; i++) {
System.out.print(arrays[i]+" ");
}
}
//反转数组
public static int[] reverse(int[] arrays){
int[] result = new int[arrays.length];
for (int i = 0,j=result.length-1; i < arrays.length; i++,j--) {
result[j] = arrays[i];
}
return result;
}
}
package top.iyunsir.array;
public class ArraysDemo05 {
public static void main(String[] args) {
//[4][2]
/*
1,2 array[0]
2,3 array[1]
3,4 array[2]
4,5 array[3]
*/
int[][] array = {{1,2},{2,3},{3,4},{4,5}};
// System.out.println(array.length);
// System.out.println(array[0].length);
for (int i = 0; i < array.length ; i++) {
for (int j = 0; j < array[i].length; j++) {
System.out.println(array[i][j]);
}
}
}
//打印数组元素
public static void printArray(int[] arrays) {
for (int i = 0; i < arrays.length; i++) {
System.out.print(arrays[i]+ "");
}
}
}
package top.iyunsir.array;
import java.util.Arrays;
public class ArrayDemo06 {
public static void main(String[] args) {
int[] a = {1,2,4,6,23123,5435,6341,211,5};
System.out.println(a); //[I@14ae5a5
//打印数组元素 Arrays.toString
// System.out.println(Arrays.toString(a));
// printArray(a);
Arrays.sort(a);//数组进行排序; 升序
System.out.println(Arrays.toString(a));
Arrays.fill(a, 2,4,0); //数组填充
System.out.println(Arrays.toString(a));
}
public static void printArray(int[] a) {
for (int i = 0; i < a.length; i++) {
if (i==0){
System.out.print("{");
}
if (i==a.length-1){
System.out.print(a[i]+"}");
}else {
System.out.print(a[i]+", ");
}
// System.out.print(a[i]+",");
}
}
}
package top.iyunsir.array;
import java.util.Arrays;
public class ArrayDemo06 {
public static void main(String[] args) {
int[] a = {1,2,4,6,23123,5435,6341,211,5};
System.out.println(a); //[I@14ae5a5
//打印数组元素 Arrays.toString
// System.out.println(Arrays.toString(a));
// printArray(a);
Arrays.sort(a);//数组进行排序; 升序
System.out.println(Arrays.toString(a));
Arrays.fill(a, 2,4,0); //数组填充
System.out.println(Arrays.toString(a));
}
public static void printArray(int[] a) {
for (int i = 0; i < a.length; i++) {
if (i==0){
System.out.print("{");
}
if (i==a.length-1){
System.out.print(a[i]+"}");
}else {
System.out.print(a[i]+", ");
}
// System.out.print(a[i]+",");
}
}
}
package top.iyunsir.array;
import java.util.Arrays;
public class ArrayDemo07 {
public static void main(String[] args) {
int[] a = {1,3,51,5,567,12,523,63};
int[] sort = sort(a); //调用完我们自己写的排序方法以后,返回一个排序后的数组
System.out.println(Arrays.toString(sort));
}
//冒泡排序
//1. 比较数组中, 两个相邻的元素,如果第一个数比第二个数大，我们就交换他们的位置
//2. 每一次比较, 都会产生出一个最大，或者最小的数字
//3. 下一轮则可以少一轮排序
//4. 依次循环, 直到结束！
public static int[] sort(int[] array){
//临时变量
int temp = 0;
//外层循环,判断我们这个要走多少次;
for (int i = 0; i < array.length-1; i++) {
boolean flag = false; //通过flag标识位减少没有意义的比较
//内层循环, 比价判断两个数,如果第一个数,比第二个数大,则交换位置
for (int j = 0; j < array.length-1-i; j++) {
if (array[j+1]< array[j]){
temp = array[j];
array[j] = array[j+1];
array[j+1] = temp;
}
}
if (flag==false){
break;
}
}
return array;
}
}
package top.iyunsir.array;
public class ArrayDemo08 {
/* 1 2 3 4 5 6 7 8 9 10
0 0 0 0 0 0 0 0 0 0 0
1 0 0 1 0 0 0 0 0 0 0 0
2 0 0 0 2 0 0 0 0 0 0 0
3 0 0 0 0 0 0 0 0 0 0 0
4 0 0 0 0 0 0 0 0 0 0 0
5 0 0 0 0 0 0 0 0 0 0 0
6 0 0 0 0 0 0 0 0 0 0 0
7 0 0 0 0 0 0 0 0 0 0 0
8 0 0 0 0 0 0 0 0 0 0 0
9 0 0 0 0 0 0 0 0 0 0 0
10 0 0 0 0 0 0 0 0 0 0 0
*/
public static void main(String[] args) {
// 1. 创建一个二维数组11*11 0: 没有棋子 1: 黑棋 2:白棋
int[][] array1 = new int[11][11];
array1[1][2] = 1;
array1[2][3] = 2;
//输出原始的数组
System.out.println("输出原始的数组");
for (int[] ints : array1){
for (int anInt : ints){
System.out.print(anInt+"\t");
}
System.out.println();
}
System.out.println("================");
//转换为稀疏数组保存
//获取有效值的个数
int sum = 0;
for (int i = 0; i < 11; i++) {
for (int j = 0; j < 11; j++) {
if (array1[i][j]!=0){
sum++;
}
}
}
System.out.println("有效值的个数:" +sum);
//2.创建一个稀疏数组的数组
int[][] array2 = new int[sum+1][3];
array2[0][0] = 11;
array2[0][1] = 11;
array2[0][2] = sum;
//遍历二维数组, 将非零的值,存放稀疏数组中
int count=0;
for (int i = 0; i < array1.length; i++) {
for (int j = 0; j < array1.length; j++) {
if (array1[i][j]!=0){
count++;
array2[count][0] = i;
array2[count][1] = j;
array2[count][2] = array1[i][j];
}
}
}
//输出稀疏数组
System.out.println("稀疏数组");
for (int i = 0; i < array2.length; i++) {
System.out.println(array2[i][0]+"\t"
+array2[i][1]+"\t"
+array2[i][2]+"\t");
}
System.out.println("================");
System.out.println("还原");
//1.读取稀疏数组
int[][] array3 = new int[array2[0][0]][array2[0][1]];
//2.给其中的元素还原它的值
for (int i = 1; i < array2.length; i++) {
array3[array2[i][0]][array2[i][1]] = array2[i][2];
}
//3.打印
System.out.println("输出还原的数组");
for (int[] ints : array1){
for (int anInt : ints){
System.out.print(anInt+"\t");
}
System.out.println();
}
}
}
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