int[]arr={71,54,58,29,31,78,2,77,82};
//1.选择排序前,先循环打印数组元素
System.out.print("排序前");
for (int i=0;i<arr.length;i++){
    System.out.print(arr[i]+" ");
}
System.out.println();
//2.进行冒泡排序
for (int i=1;i<arr.length;i++) {
    for(int j=0;j<arr.length-i;j++){
        if (arr[j]<arr[j+1]){
            int temp=arr[j];
            arr[j]=arr[j+1];
            arr[j+1]=temp;
        }
    }
}
System.out.print("排序后:");
for (int i=0; i<arr.length;i++){
    System.out.print(arr[i]+" ");