在此代码中,我遇到NullPointerException
错误:
int k=3;
Thread[] th = null ;
for(int i=0; i<k; i++){
th[i] = new ThreadF(step[i],step[i+1],"Th"+(i+1));
}
但是这没有错误,一切都很好:
Thread th1 = new ThreadF(step[0],step[0+1],"Th1");
Thread th2 = new ThreadF(step[1],step[1+1],"Th2");
Thread th3 = new ThreadF(step[2],step[2+1],"Th3");
为什么呢?
答案 0 :(得分:4)
Thread[] th = null;
应该是:
Thread[] th = new Thread[k];
如果启用警告或使用IDE,您应该看到:
空指针访问:变量th在此位置只能为空