What will be written to the standard output when the following program is run？（）  
public class Q03e4 {  
public static void main（String args[]） {  
String space = " "；  
String composite = space + "hello" + space + space；  
composite.concat（"world"）；  
String trimmed = composite.trim（）；  
System.out.println（trimmed.length（））； 
 }  
}  

GiventhatfileisareferencetoaFileobjectthatrepresentsadi...

单项选择题Given that file is a reference to a File object that represents a directory， which code fragments will succeed in obtaining a list of the entries in the directory？（）  

Given the following code, write a line of code that, wh...

填空题

Given the following code, write a line of code that, when inserted at the indicated location, will make the overriding method in Extension invoke the overridden method in class Base on the current object.  
class Base {  
public void print() {  
System.out.println("base");  
}  
}  
class Extention extends Base {  
public void print() {  
System.out.println("extension");  
// insert line of implementation here  
}  
} 
 public class Q294d {  
public static void main(String args[]) {  
Extention ext = new Extention();  
ext.print();  
}  
}  
Fill in a single line of implementation.（）

Whichstatementsaretrue，giventhecodenewFileOutputStream（...

单项选择题Which statements are true， given the code new FileOutputStream（"data"， true） for creating an object of class FileOutputStream？（）