Java数组的遍历与求和知识点

public class OneArry{  public static void main(String[] args) {   double[] num = {1.9, 2.9, 3.4, 3.5,10,-1};   num[0]=new Double(2); //通过下标把1.9变为2.0  double sum = 0;   for (int i = 0; i < num.length; i++) { //遍历 	 System.out.println(num[i]); 	 sum+=num[i]; //求和  }   System.out.println("一维数组之和为 " + sum);  }  }

2.02.93.43.510.0-1.0一维数组之和为 20.8

public class TwoArry{   public static void main(String[] args) {  	int sum=0;    int num [][] ={         {1,2,3,4,5},         {6,7,8,9,10},         {11,12,13,14,15},         {16,17,18,19,20},         {21,22,23,24,25}} ;      System.out.println("输出二维数组:");    num[0][0]=new Integer(100); //通过下标把数组里的1变为100     for(int i=0;i<num.length;i++){ //遍历，排列       for( int j=0;j<num[i].length;j++){          System.out.print(num[i][j]+"/t");         sum+=num[i][j]; //求和        		}      System.out.println();         }     System.out.println("二维数组之和为："+sum);    }  }

输出二维数组:100	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20	21	22	23	24	25	二维数组之和为：424

public class TwoArry{  	 public static void main(String args[ ]){  	     int[][]num=new int[5][5];                     	     int count=1; //数组从1开始循环 	     int sum=0;	     for(int i=0;i<num.length;i++){  	      for(int j=0;j<num[i].length;j++){	        num[i][j]=count++; //count添加到数组里	        sum+=num[i][j]; //求和//	        System.out.println(num[i][j]); //打印出所有数组	       }	     }	     System.out.println("二维数组之和为："+sum);	     System.out.println("输出二维数组:"); 	     for(int i=0;i<num.length;i++){ //进行排列 	       for(int j=0;j<num[i].length;j++){  	         System.out.print(num[i][j]+"/t");	       }       	       System.out.println();     	   }  	 }  } 

二维数组之和为：325输出二维数组:1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20	21	22	23	24	25