Java数组删除会带来意想不到的结果吗？

Question

The following code is part of a program which takes the values of array ar except for variable z, and copies it onto a different array called ar2. The result should be all the numbers except negative two (19, 1, 17, 17), but currently the result is 19 1 17 17 -2 19 1 17 17 -2 19 1 17 17 -2 19 1 17 17 -2.

public class Second_tiny {

    public static void main(String[] args) {
        int[] ar = { 19, 1, 17, 17, -2 };
        int z = ar[0];

        for (int i = 0; i < (ar.length); i++) {
            if (z > ar[i]) {
                z = ar[i];

            }
        }
        // second pass
        int[] ar2 = new int[ar.length];
        int zero = 0;
        for (int x = 0; x < (ar.length); x++) {
            if (ar[x] == z) {
                continue; // If it is equal to z go back to the loop again

            }
            ar2[zero++] = ar[x];

            for (int i = 0; i < ar.length; i++) {
                System.out.println(ar[i]);
            }
            /*
             * //2nd pass copy all items except smallest one to 2nd array int[] ar2= new int[ar.length-1]; int curIndex = 0; for (i=0; i<ar.length; i++) { if (ar[i]==z) continue; ar2[curIndex++] =
             * ar[i]; }
             */

        }

    }
}    

Answer 1

Java 8 way:

        int[] ar = { 19, 1, 17, 17, -2 };
        int min = Arrays.stream(ar).min().getAsInt();
        int[] ar2 = Arrays.stream(ar).filter(s -> s!=min).toArray();
        System.out.println(Arrays.toString(ar2));

Answer 2

You're printing out your original array 4 times in this block:

for (int i = 0; i < ar.length; i++) {
    System.out.println(ar[i]);
}

That block should be outside of your loop, and should reference ar2 instead of ar .

for (int x = 0; x < (ar.length); x++) {
    if (ar[x] == z) {
        continue; // If it is equal to z go back to the loop again
    }

    ar2[zero++] = ar[x];
}

for (int i = 0; i < ar2.length; i++) {
    System.out.println(ar2[i]);
}

This will give you the following result:

19
1
17
17
0

The last 0 appears because 0 is the default value for int s. Your ar2 array is 5 elements long, and for the last element the default value is never replaced.

Answer 3

You could use Math.min(int, int) to determine your lowest value. Your second array should be one element smaller. I suggest guarding against removing more than one value. And you could use Arrays.toString(int[]) to print the second array . Something like,

int[] ar = { 19, 1, 17, 17, -2 };
int z = ar[0];
for (int i = 1; i < ar.length; i++) {
    z = Math.min(z, ar[i]);
}
// second pass
int[] ar2 = new int[ar.length - 1];
boolean first = true;
for (int x = 0; x < ar.length; x++) {
    if (ar[x] == z && first) {
        first = false;
        continue; // If it is equal to z go back to the loop again
    }
    int y = x - (!first ? 1 : 0);
    ar2[y] = ar[x];
}
System.out.println(Arrays.toString(ar2));

Output is

[19, 1, 17, 17]

Answer 4

you code is right mistakenly you have given one extra for loop.i have done comment on that for loop.use the following code u will get the desired output.

public class HelloWorld {

    public static void main(String[] args) {
        int[] ar = { 19, 1, 17, 17, -2 };
        int z = ar[0];

        for (int i = 0; i < (ar.length); i++) {
            if (z > ar[i]) {
                z = ar[i];

            }
        }
        // second pass
        int[] ar2 = new int[ar.length];
        int zero = 0,i=0;

        for (int x = 0; x < (ar.length); x++) {
            if (ar[x] == z) {
                continue; // If it is equal to z go back to the loop again

            }
            ar2[zero++] = ar[x];

          //  for (int i = 0; i < ar.length; i++) {
                System.out.println(ar[i]);
                i++;
          //  }
            /*
             * //2nd pass copy all items except smallest one to 2nd array int[] ar2= new int[ar.length-1]; int curIndex = 0; for (i=0; i<ar.length; i++) { if (ar[i]==z) continue; ar2[curIndex++] =
             * ar[i]; }
             */

        }

    }
}    

output is:

19

1

17

17