黑马程序员--【数组】--

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打印出数组   [1,2,2,3,2,4,3,2]
=============================================
package Wuyuejichu;

public class ShuzuDemo2 {

       
       public static void main(String[] args) {
               // TODO Auto-generated method stub
               
               int[] arr={1,2,2,3,2,4,3,2};
               printArry(arr);
       }
       
       public static void printArry(int[] arr){
               System.out.print("[");
               for(int x=0;x<arr.length;x++){
                       if(x!=arr.length-1){
                               System.out.print(+arr[x]+",");
                       }
                       else{
                               System.out.print(+arr[x]+"]");
                       }
               }
       }
}
======================================
查找数组中的做大数：
package Wuyuejichu;

public class ShuzuDemo3 {

       
       public static int getMax(int[] arr){
               int max=arr[0];
               for(int x=0;x<arr.length;x++){
                       if(arr[x]>max){
                               max=arr[x];
                       }
                       
               }
               return max;
               
       }

       public static void main(String[] args) {
               // TODO Auto-generated method stub
               int[] arr={2,3,5,1,2,8,5};
               int max=getMax(arr);
               System.out.println(max);
       }

}
========================================


package Wuyuejichu;
public class ShuzuDemo4 {
       public static void selectSort(int[] arr){
               for(intx=0;x<arr.length-1;x++){       //arr.length-1 最后 不用进行比较
                       for(int y=x+1;y<arr.length;y++){
                               if(arr[x]>arr[y]){
                                       int tmp=arr[x];
                                       arr[x]=arr[y];   //借用第三方比较
                                       arr[y]=tmp;
                               }
                       }
               }
       }
       public static void main(String[] args) {
               // TODO Auto-generated method stub
               int[] arr={3,4,7,2,1,9,6};
               //比较前的打印前
               printArry(arr );
               selectSort(arr);
               //比较后的打印
               printArry(arr);
       }
       //打印数组
       public static void printArry(int[] arr){
               System.out.print("{");
               for(int x=0;x<arr.length;x++){
                       if(x!=arr.length-1)
                               System.out.print(arr[x]+",");
                       else
                               System.out.println(arr[x]+"}");
               }
       }
}
===================================
冒泡排序：相邻的两个元素进行比较，如果符合条件要求进行交换

package Wuyuejichu;

import java.util.Arrays;
//选择逐一排序
public class ShuzuDemo4 {
       public static void selectSort(int[] arr){
               for(int x=0;x<arr.length-1;x++){
                       for(int y=x+1;y<arr.length;y++){
                               if(arr[x]>arr[y]){
                                       
                                       swap(arr,x,y);
                               }
                       }
               }
       }
       //冒泡排序
       public static void bubblesort(int[] arr){
               for(int x=0;x<arr.length-1;x++){
                       for(int y=0;y<arr.length-x-1;y++){//-x:让每一次比较元素减1   -1：避免数组越界
                               if( arr[y]<arr[y+1]){
                                        
                                       swap(arr,y,y+1);
                               }
                       }
               }
               
       }
       //封装函数   交换
       public  static void swap(int[] arr ,int a,intb){
               int tmp=arr[a];
               arr[a]=arr[b];
               arr[b]=tmp;
       }
       public static void main(String[] args) {
               // TODO Auto-generated method stub
               int[] arr={3,4,7,2,1,9,6};
       System.out.println("原数组：");
//               //比较前的打印前
               printArry(arr );
               selectSort(arr);
//               //比较后的打印
               System.out.println("选择注意排序后的数组");
               printArry(arr);
               System.out.println("JAVA中自定义的Arrays.sort升序排序：");
               Arrays.sort(arr);  //JAVA中定义好的升序排序，开发中用到
               printArry(arr);
               System.out.println("冒泡排序：");
               bubblesort(arr);
               printArry(arr );
       }
       //打印数组
       public static void printArry(int[] arr){
               System.out.print("{");
               for(int x=0;x<arr.length;x++){
                       if(x!=arr.length-1)
                               System.out.print(arr[x]+",");
                       else
                               System.out.println(arr[x]+"}");
               }
       }
}                                               






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