选择题

class Person {
	String name = "No name";
	public Person(String nm) {
		name = nm;
	}
}
class Employee extends Person {
	String empID = "0000";
	public Employee(String id) {
		super(" ");//要调用父类的有参构造方法否则报错
		empID = id;
	}
}
public class Test01 {
	public static void main(String args[]) {
		Employee e = new Employee("123");
		System.out.println(e.empID);
	}
}

public class Test01 {
	private static void testMethod(){
		System.out.println("testMethod");
	}
	public static void main(String[] args) {
		((Test01)null).testMethod();
		//testMethod
	}
}

public class Test01{
	String str=new String("hello");
	char[]ch={'a','b'};
	public static void main(String args[]){
		Test01 ex=new Test01();
		ex.change(ex.str,ex.ch);
		
		System.out.print(ex.str+" and ");
		System.out.print(ex.ch);
		//hello and cb
	}
	public void change(String str,char ch[]){
		str="test ok";//不改变
		ch[0]='c';//改变
	}
}

public class Test01{
	public static void main(String[] args) {
		int i=0;
		Integer j = new Integer(0);
		System.out.println(j);//0
		System.out.println(i==j);//true
		System.out.println(j.equals(i));//true		
	}
}

编程题
题目1

public class UnusualAdd {
   	public static int addAB(int A, int B) {
		int s1 = A&B;
//		System.out.println(s1);
		int s2 = A|B;
//		System.out.println(s2);
		int c = s1+s2;
        return c;
    }
}