Java数组索引超出范围异常处理

Question

Given the following Java codes:

int test = createIntData(Column[8]);

private int createIntData (String realData) {
    if (realData == null) {
        return (int) (Math.random()*100); 
    }
    else {
        return Integer.parseInt(realData);
    }
}

This throws exception like this：

Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException

This is because the argument only have an maximum index of 4. Then how to change the program to realize the function that: once the argument is out of index, return the value:

Math.random() * 100

Answer 1

If 8 is outside the range of Column 's length, that error is what you get. Change this

int test = createIntData(Column[8]);

to (using the ternary )

int test = createIntData((8 < Column.length) ? Column[8] : null);

Answer 2

There are 2 severe problems:

1.You should check, whether a given array index does exist:

Column[] array = new Column[someCapacity];
//fill the array

int i = 8;

if( i < array.length && i > -1 ){
    int test = createIntData(array[i]);
}

2.The array's type( Column ) does not match the createIntData() input parameter ( String )

Answer 3

I would go with allowing for check inside the method, by passing array and index:

public int createIntData(String[] values, int index) {
    if (values != null && index >= 0 && index < values.length) {
        return Integer.parseInt(values[index]);
    }
    return (int) (Math.random()*100);
}

Call it:

int test = createIntData(Column, 8);

This way the method can safely be called with any input (I left the potential exception in the parseInt, though)