冒泡排序`交换排序·二分查找

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}

public class ArrayTest {
public static void main(String[] args) {
int[] a = new int[] {1,2,3};
int [] b = new int[4];
System.arraycopy(a,0,b,0,4);
for(int i = 0;i<b.lentth;i++) {
System.out.println(b[i]);
}
}
}

三维数组。type[][][] a = new type[2][3][4];

public class ArrayTest {
poublic static void main(String[] args) {
int [][][] a =new int[2][3][4];
System.out.println(a instanceof int[][][]);
System.out.println(a instanceof object);

System.out.println(a[0] instanceof int[][]);

System.out.println(a[0][0] instanceof int[]);

for(int i = 0; i<a.length; i++) {
for (int j = 0;j <a[i].length;j++){
for(int k = 0;k <a[i][j].length;k++){
a[i][j][k] = 100;
}
}
}
}
}

冒泡排序：（掌握交换排序，快速排序的原理与实现方式）

public class BubbleSortTest {
public static void bubbleSort(int[] array){
for(int i = 0;i < array.length - 1; i++) {
for(int j = 0;j < array.length - i - 1;j++) {
if(array[j] > array[j+1]) {
int temp = array[j];
array[j] = array[j+1];
array[j+1]= temp;
}
}

System.out.println("第" + (i + 1) + "次排序");
for(int k = 0; k < array.length; k++) {
System.out.print(array[k] + " ");
}
System.out.println();
}
}
public static void main(String[] args) {
int[] array = {4,9,2,8,6,1};
bubbleSort(array);
}
}

int[] a = new int[10];
int[] a = {new int[]}{1,2,3,4,5,6}
数组的属性 length是public final int的，一旦确定不能改变。

二维数组是一种平面的二维结构
int[][] a = new int[2][3];
第一个方括号里代表行，第二个代表列

三维数组
int[][][] a = new type[2][3][4];

二分查找（Binary Search）:待查找的数组要有序
import java.util.Random;
public class RandomTest {
public static void main(String[] args) {
Random random = new Random();
for(int i = 0;i < 50;i++){
//System.out.println(random.nextInt(41)+10);
//}
double result = Math.random();
result *= 41;
int result2 = (int)result;
result2+= 10;
System.out.println(result2);
}
}

import java.util.Random;
public class RandomTest {
public static void main(String[] args) {
int[] count = new int[41];
Random random = new Random();
for(int i = 0; i<50;i++){
int number = random.nextInt(41)+ 10;
count [number -10]++;
}
for(int i = 0; i<count.length; i++) {

}
}
}

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