Question

我可以问一个关于我头衔的问题。由于我是java的新手，我在程序中对异常处理有点困惑。我需要做的是，当用户输入错误的输入时需要循环异常。对于以下编码，它只执行ArrayOutOfBounds异常。当我输入字符串/符号/十进制值时，为什么不执行FormatNumberException。它仅显示在输出节中，但不显示在showMessageDialog输出中。我尝试使用多个异常处理Catch Multiple Java Exception并且仍然相同。你能帮我解决这个问题吗？任何答案将不胜感激。抱歉我的英语不好。

public class TestRandomArray {

    public static void main(String[] args) {
        Random ran = new Random(); // create instant object from class Random.
        int array[] =new int[100]; //set an array variable with array size of 100
        int maxNumber = 150; //set the limit of the random number to generate

        for (int i = 0; i < array.length; i++) { 
            array[i] = ran.nextInt(maxNumber) + 1; //+1 means that the array number should not contain with 0 value. 1-150.
            //System.out.println(array[i]);                
        }
        //for(int i : array){
            //System.out.println(i + ",");  //this for method is other technique to print the list of array.
        //}        
            do {   
                    String input = JOptionPane.showInputDialog(null, "Enter index"); //Get input from user
                    int choosenIndex = Integer.parseInt(input); //change the string to int type.
                try {  
                    if(choosenIndex >= 0 || choosenIndex <= array.length)  
                        JOptionPane.showMessageDialog(null, "The value of choosen index in the array is : "
                        + array[choosenIndex]); //display the choosen index value.
                        System.exit(0);
                }catch (ArrayIndexOutOfBoundsException e){
                    if (choosenIndex < 0 || choosenIndex > array.length) {
                        JOptionPane.showMessageDialog(null,
                        "Index is out of bound. Enter from 0-99"); //display error for indexoutbound.
                    }
                }catch(NumberFormatException e){
                        JOptionPane.showMessageDialog(null, "Only integer allowed.");//display other error occured.
                }
            } while (true);
    }
}

Answer 1

Integer.parseInt(input);

此声明在您的try块之外。它必须在里面，以便你的程序跳转到catch(NumberFormatException e)块。

Answer 2

公共类TestRandomArray {

loginPoints

}

Answer 3

请仅进行以下更改，有效，

  int choosenIndex = 0;
            do {   
                    String input = JOptionPane.showInputDialog(null, "Enter index"); //Get input from user
                try {  
                     choosenIndex = Integer.parseInt(input); //change the string to int type.
                    if(choosenIndex >= 0 || choosenIndex <= array.length)  
                        JOptionPane.showMessageDialog(null, "The value of choosen index in the array is : "
                        + array[choosenIndex]); //display the choosen index value.
                        System.exit(0);
                }catch(NumberFormatException e){
                    JOptionPane.showMessageDialog(null, "Only integer allowed.");//display other error occured.
                }catch (ArrayIndexOutOfBoundsException e){
                    if (choosenIndex < 0 || choosenIndex > array.length) {
                        JOptionPane.showMessageDialog(null,
                        "Index is out of bound. Enter from 0-99"); //display error for indexoutbound.
                    }
                }
            } while (true);

循环处理异常

3 个答案: