StringBuilder [] wire = new StringBuilder[20]; 小弟不才 问下如何定义这个组呢wire[2].append("hellow World!");Exception in thread "main" java.lang.NullPointerException
at panda.packing.PreRouting.routingLE(PreRouting.java:90)
at panda.packing.Main.main(Main.java:32)报空指针错误菜鸟求教
at panda.packing.PreRouting.routingLE(PreRouting.java:90)
at panda.packing.Main.main(Main.java:32)报空指针错误菜鸟求教
wire[0] = new StringBuilder("hellow World!");
wire[1] = new StringBuilder("hellow World1!");你wire[0]的对象都没生成,使用append肯定 NullPointerException
你这样是定义了一个长度为20的空字符串数组。
对一个空值调用方法,必然报空指针错误。