Tag: 按值调用

为什么修改了ArrayList参数，但没有修改String参数？

public class StackOverFlow { public static void main(String[] args) { ArrayList al = new ArrayList(); al.add(“A”); al.add(“B”); markAsNull(al); System.out.println(“ArrayList elements are “+al); String str = “Hello”; markStringAsNull(str); System.out.println(“str “+ str); } private static void markAsNull(ArrayList str){ str.add(“C”); str= null; } private static void markStringAsNull(String str){ str = str + “Append me”; str = null; } […]