public class Learner {
    public static void main(String[] args) {
        String[] dataArr = new String[4];
        dataArr[1] = "Bill";
        dataArr[2] = "Steve";
        dataArr[3] = "Larry";
        try{
            for(String data : dataArr){
                System.out.print(data+" ");
            }
        }catch(Exception e){
            System.out.println(e.getClass());
        }
    }
}
 
 这本书将说明这将打印：null Bill Steve Larry 
 
 这让我感到困惑，因为我认为使用null访问任何数据都会抛出NullPointerException。 在访问具有空值的数组时是否曾经抛出异常？ 
 
 或者是system.out.println（），保存恩典？ 你可以使用for循环访问任何空值，只要不说你在上面调用data.length（）吗？ 

public class Learner {
    public static void main(String[] args) {
        String[] dataArr = new String[4];
        dataArr[1] = "Bill";
        dataArr[2] = "Steve";
        dataArr[3] = "Larry";
        try{
            for(String data : dataArr){
                System.out.print(data+" ");
            }
        }catch(Exception e){
            System.out.println(e.getClass());
        }
    }
}
 
The book states this will print: null Bill Steve Larry
 
This confuses me as I thought accessing any data with null will throw a NullPointerException. Is there ever a time when an exception is thrown when accessing an array with null values?
 
Or is system.out.println(), the saving grace? Can you access any null value with a for loop, as long as your not say calling data.length() on it?

原文：https://stackoverflow.com/questions/32192813