java题库

class J_Test

{

public static void main(String args[ ])

{

String a=new String(“A”);

StringBuffer b=new StringBuffer(“B”);

mb_operate(a,b);

System.out.println(a+“.”+b);

}

static void mb_operate(String x,StringBuffer y)

{

x=new String(“C”);

y=new StringBuffer(“D”);

}

}

class J_Animal

{

public abstract void mb_index( )

}

Class J_Dog extends J_Animal

{

public void mb_index( )

{

System.out.print(“1”);

}

}

Class J_Cat extends J_Animal

{

public void mb_index( )

{

System.out.print(“2”);

}

}

Public class J_Test

{

public static void main(String args[ ])

{

J_Animal d=new J_Dog( );

d.mb_index( );

d=new J_Cat( );

d.mb_index( );

}

}

public class J_Test

{

public static void main(String args[ ])

{

int [ ]a=new int[5];

A.length=10;

System.out.println(a.length);

}

}