我似乎无法将 double 转换为 int

Question

     int a = 1;
  double b = 1.0;
  double l = 10;

for (int i=1;i<=3;i++){

  a=(int) b;
   System.out.println("");
   for (a=a;a<=l;a++){
       System.out.print(a+" ");           
   }
   l=l*2;
   System.out.println("");

   for ( b=a;b<=l;b++){
System.out.print(b+" ");

a=(int) b;

doesn't work please help. The output should display:

1 2 3 4 5 6 7 8 9 10 11.0 12.0 13.0 14.0 15.0 16.0 17.0 18.0 19.0 20.0 21 22 23 24 25 26 27...

alternating from integer to double every time till it reaches 100.

Answer 1

Try this:

for(int i = 0 ; i < 100 ; i+=10){

        for(int j = 1 ; j <= 10 ; j++){

            if((i/10)%2 != 0){
                double d = i+j;
                System.out.print(d+" ");
            }else{
                System.out.print((i+j)+" ");
            }

        }
    }

You can also do it like this instead of converting it to a double,

            if((i/10)%2 != 0){
                System.out.print((i+j)+".0 ");
            }

Answer 2

From the looks of the given code, it appears that you forgot to add 2 closing brackets at the end. Here's your code when I added the closing brackets and put them inside a main function:

public static void main (String[] args)
  {
    int a = 1;
    double b = 1.0;
    double l = 10;

    for (int i=1;i<=3;i++){

      a=(int) b;
      System.out.println("");
      for (a=a;a<=l;a++){
        System.out.print(a+" ");           
      }
      l=l*2;
      System.out.println("");

      for ( b=a;b<=l;b++){
        System.out.print(b+" ");

        a=(int) b;
      }
    }
  }
}

Here's the output of your program:

1 2 3 4 5 6 7 8 9 10 
11.0 12.0 13.0 14.0 15.0 16.0 17.0 18.0 19.0 20.0 

21.0 22.0 23.0 24.0 25.0 26.0 27.0 28.0 29.0 30.0 31.0 32.0 33.0 34.0 35.0 36.0 37.0 38.0 39.0 40.0 

41.0 42.0 43.0 44.0 45.0 46.0 47.0 48.0 49.0 50.0 51.0 52.0 53.0 54.0 55.0 56.0 57.0 58.0 59.0 60.0 61.0 62.0 63.0 64.0 65.0 66.0 67.0 68.0 69.0 70.0 71.0 72.0 73.0 74.0 75.0 76.0 77.0 78.0 79.0 80.0

Although the output is not what you wanted, it shows that your conversion from double to int works. The problem is likely the syntax error. If you're only interested in the output, I can provide an alternative approach:

public static void main (String[] args) throws java.lang.Exception
    {
        for (int i = 1; i < 100; ++i) {
            if (((i-1) / 10) % 2 == 0) {
                System.out.print(i);
            } else {
                System.out.print(Integer.toString(i) + ".0");
            }
            System.out.print(" ");
        }
        System.out.print(100.0);
    }