int [][] array = {{1,2,3},{1,4}};
    System.out.println(array[1][2]);

Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 2

 at demo.Array.main(Array.java:31)

package home_work_4_17;
abstract class Employee{
 abstract double earnings();
}
class YearWorker extends Employee{
 double earnings(){
  System.out.println("按年领取1000");
  return 1000;
 }
}
class MonthWorker extends Employee{
 double earnings(){
  System.out.println("按月领取100");
  return 100;
 }
}
class WeekWorker extends Employee{
 double earnings(){
  System.out.println("按星期领取10");
  return 10;
 }
}
class Company{
 int n;
 //该公司的人数
 public Company(int n) {
  this.n=n;
  // TODO Auto-generated constructor stub
 }
 Employee E[]=new Employee[n];
 double cal(){
  //返回薪水综合
  double sum=0;
  for (int j=0;j<n;j++){
   sum+=E[j].earnings();
  }
  return sum;
 }
}
public class work_2 {
 public static void main(String args[]) {
  Company c=new Company(3);
  c.E[0]=new WeekWorker();
  c.E[1]=new MonthWorker();
  c.E[2]=new YearWorker();
  System.out.println("总支出："+c.cal());
 }
}

class Company{
  int n;  //该公司的人数
   Employee E[]； 
  public Company(int n) {
    this.n=n;// TODO Auto-generated constructor stub
    E=new Employee[n];  
   }
  double cal(){    //返回薪水综合
    double sum=0;
    for(int j=0;j<n;j++){
      sum+=E[j].earnings();
    }
    return sum;
  }
}

package test_a;
class people{
  int n;
  Student s[]=new Student[n];
  public people(int n) {
    this.n=n;// TODO Auto-generated constructor stub
  }
}
class Student{
  int number;
}
public class Cdcs {
  public static void main(String args[]) {
    people p=new people(3);
    System.out.println(p.s.length);
  }
}