Java big data platform development study notes (8)-selection order

1. Data structure and algorithm:

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1.1. Create a selection sort method:

 public static void selectSort(int[] arr){
    
    
     for (int i=1; i<arr.length; i++){
    
    
         int index = i-1;
         for (int j=i; j<arr.length; j++){
    
    
             if(arr[index] > arr[j]){
    
    
                 index = j;
             }
         }
         if(index != i-1){
    
    
             if (arr[i - 1] > arr[index]) {
    
    
                 int temp = arr[i - 1];
                 arr[i - 1] = arr[index];
                 arr[index] = temp;
             }
         }
     }
 }
 

1.2. Main method:

public static void main(String[] args) {
    
    
     //随机创建8万 个数据
     int arr[]= new int[80000];
     for(int i=0; i<arr.length; i++){
    
    
         arr[i] = (int)(Math.random()*80000);
     }
     //计算 冒泡排序时间
     double start = System.currentTimeMillis();
     System.out.println("计时开始：");
     selectSort(arr);//此处写要测试的代码
     double end = System.currentTimeMillis();
     System.out.println("计时结束, 共耗时:"+ (double)((end-start)/1000) +"秒");
}
    

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• Written by ChiKong_Tam on September 9, 2020