如下的代码有什么问题?
package test;
public class AssignTest {
public long[][] time = null;
public AssignTest() {
}
public void setArray(long[][] a) {
a = new long[3][4];
for (int i = 0; i < a.length; i++) {
for (int j = 0; j < a[i].length; j++) {
a[i][j] = i * j;
}
}
}
public void printArray() {
setArray(this.time);//通过这个函数对成员变量进行赋值
for (int i = 0; i < time.length; i++) {
for (int j = 0; j < time[i].length; j++) {
System.out.println(time[i][j]);
}
}
}
public static void main(String[] args) {
AssignTest at = new AssignTest();
at.printArray();
}
}
java.lang.NullPointerException
at test.AssignTest.printArray(AssignTest.java:20)
at test.AssignTest.main(AssignTest.java:29)
Exception in thread "main"