java.util.List

[shana07]

Hi again, would like to consult about List problem.

//start code

 java.util.List ifs = new java.util.ArrayList();

// we're in the 'getMonitor' method

   Instruction insn = jvm.getLastInstruction();     
   ……… 
   ………
   if (insn instanceof IfInstruction) 
{
     IfInstruction iff = (IfInstruction) insn;
     Object position = insn.getOffset();
     boolean value = iff.getConditionValue();
     ifs.add(new Entry(position, value));

    System.out.print(position);
    System.out.println();
    System.out.print(value);
    System.out.println();
                                
    Iterator iter = ifs.iterator();
    while (iter.hasNext()) {
                  System.out.println("string " + iter.next());
                  }
    System.out.print(ifs.size());
    System.out.println();              
   }
// ... the rest of the method are here

class Entry {
   public Object position;
   public boolean value;

   public Entry(Object position, boolean value) {
     this.position = position;
     this.value    = value;
   }
}

Now what happen is I need to call those fields above in a method ‘report’
(in the same file – TestDriver.java ). Here comes my question:
1. How am I supposed to call single value/position without call Entry as a whole?
E.g: I want to compare value of index 1 and index 0 - which I have read inputs from Array.

void report( )
………
………
//ifs.get(1) != ifs.get(0) 
//I don't need this because it is getting compare the
//whole Entry.I need something like this: 

if (ifs.value(1) != ifs.value(0)) //For sure errors encountered! 
   {
        System.out.println (“A”);
    }
    else 
    {
        System.out.println (“B”);
    }

Please advise me. thanks guys...

[r035198x]

Hi again, would like to consult about List problem.

//start code

 java.util.List ifs = new java.util.ArrayList();

// we're in the 'getMonitor' method

Instruction insn = jvm.getLastInstruction(); 
……… 
………
if (insn instanceof IfInstruction) 
{
IfInstruction iff = (IfInstruction) insn;
Object position = insn.getOffset();
boolean value = iff.getConditionValue();
ifs.add(new Entry(position, value));
 
System.out.print(position);
System.out.println();
System.out.print(value);
System.out.println();
 
Iterator iter = ifs.iterator();
while (iter.hasNext()) {
System.out.println("string " + iter.next());
}
System.out.print(ifs.size());
System.out.println(); 
}
// ... the rest of the method are here

class Entry {
public Object position;
public boolean value;
 
public Entry(Object position, boolean value) {
this.position = position;
this.value = value;
}
}

Now what happen is I need to call those fields above in a method ‘report’
(in the same file – TestDriver.java ). Here comes my question:
1. How am I supposed to call single value/position without call Entry as a whole?
E.g: I want to compare value of index 1 and index 0 - which I have read inputs from Array.

void report( )
………
………
//ifs.get(1) != ifs.get(0) 
//I don't need this because it is getting compare the
//whole Entry.I need something like this: 
 
if (ifs.value(1) != ifs.value(0)) //For sure errors encountered! 
{
System.out.println (“A”);
}
else 
{
System.out.println (“B”);
}

Please advise me. thanks guys...

Do you have objects of type Entry in the ArrayList? Do you want to compare two Entry objects using the attribute position only?

[shana07]

I’m not too sure to answer your Q. What I’ve understood is Yes I have objects of type Entry. First I ran those codes with int a[0] and try to record the attribute value at each IF* bytecode. So the output from this code giving – 4 Entry for first execution.

Iterator iter = ifs.iterator();
while (iter.hasNext()) 
{
   System.out.println("string " + iter.next());  }
System.out.print(ifs.size());

Then I ran again the execution to execute second int a value from array and try to compare the current ifs.value of int a[1] with previous ifs.value of int a[0]. So in short - to compare two Entry of two objects int a[1] and int a[0] using attribute ‘value’ only.

[shana07]

Then I ran again the execution to execute second int a value from array and try to compare the current ifs.value of int a[1] with previous ifs.value of int a[0]. So in short - to compare two Entry of two objects int a[1] and int a[0] using attribute ‘value’ only.

Sorry for confusing you guys..I think to compare two collection objects (lists) for the attribute 'value' only. e.g
first List - run execution with int a = 1 until finish
second List - run execution with in a = 5 until finish and this time I need to compare the attribute 'value' for the two Lists. ...

let me know if still dont get it....
Shana

[r035198x]

I’m not too sure to answer your Q. What I’ve understood is Yes I have objects of type Entry. First I ran those codes with int a[0] and try to record the attribute value at each IF* bytecode. So the output from this code giving – 4 Entry for first execution.

Iterator iter = ifs.iterator();

while (iter.hasNext()) 

{

System.out.println(\"string \" + iter.next()); }

System.out.print(ifs.size());

Then I ran again the execution to execute second int a value from array and try to compare the current ifs.value of int a[1] with previous ifs.value of int a[0]. So in short - to compare two Entry of two objects int a[1] and int a[0] using attribute ‘value’ only.

To compare two Entry objects using value only, add a compareTo method in the Entry class which compares the values

 public int compareTo (Entry e) { 

if(value < e.value) {

   return -1;

}

else if(value == 0) {

   return 0;

}

else {

return 1;

}

}

Now simply use that method to compare two Entry objects using value only.

[shana07]

Could you please tell me why I got this error?

java.lang.Error : Unresolved compilation problem:
The method compareTo(Objec t) is undefined for the type TestDriver

I call method compareTo such this:
(as mentioned above I want to compare two Entry objects)

 void report (String header) 
  {
    final int EQUAL = 0;
    System.out.println(header);
    for (int i = 1; i < ifs.size(); i++) 
    {
       int comparison = compareTo(ifs.get(0));
       if (comparison != EQUAL) 
       {
   System.out.println ();
  System.out.println ("A DIFFERENT BRANCH HAS BEEN FOUND:" +IfCount);
  break;
            }
        else 
        {
    System.out.println ("FAILED TO FIND A DIFFERENT BRANCH:" +IfCount);
    break;
        }       
    }

[shana07]

Maybe you can help me to explain in short what's actually doing in method 'compareTo' especially when you give return 1 and etc.

[r035198x]

Maybe you can help me to explain in short what's actually doing in method 'compareTo' especially when you give return 1 and etc.

The compareTo method is a method that you are using to compare 2 Entry objects. This can result in three possiblities. the objects might be equal (return 0) the current Object might be less than the given object (return -1) while the other option returns 1. the return values are what we will check to see the result of the comparison.

[r035198x]

Could you please tell me why I got this error?


I call method compareTo such this:
(as mentioned above I want to compare two Entry objects)

void report (String header) 
{
final int EQUAL = 0;
System.out.println(header);
for (int i = 1; i < ifs.size(); i++) 
{
int comparison = compareTo(ifs.get(0));
if (comparison != EQUAL) 
{
System.out.println ();
System.out.println ("A DIFFERENT BRANCH HAS BEEN FOUND:" +IfCount);
break;
}
else 
{
System.out.println ("FAILED TO FIND A DIFFERENT BRANCH:" +IfCount);
break;
} 
}

You said you wanted to compare two Entry objects, so you should put the method compareTo inside the Entry class.

[shana07]

Alright in my case, what need to be compared is 'boolean' value. I want to compare (currentobject != previousobject) - in terms of values either both are TRUE/FALSE.

public int compareTo (Entry e) 
   { 
      if(value != e.value) 
       {
           return -1;
        }
       else if(value == e.value)
       {
           return 0;
       }
       else 
       {
           return 1;
       }
    }

could you please take a look at the error above....

[shana07]

You said you wanted to compare two Entry objects, so you should put the method compareTo inside the Entry class.

Yes I did put it....

class Entry
{
   public Object position;
   public boolean value;

   public Entry(Object position, boolean value)
 {
     this.position = position;
     this.value    = value;
   }
   
   public int compareTo (Entry e) 
   { 
      if(value != e.value) 
       {
           return -1;
        }
       else if(value == e.value)
       {
           return 0;
       }
       else 
       {
           return 1;
       }
    }  
}

[r035198x]

Yes I did put it....

class Entry
{
public Object position;
public boolean value;
 
public Entry(Object position, boolean value)
{
this.position = position;
this.value = value;
}
 
public int compareTo (Entry e) 
{ 
if(value != e.value) 
{
return -1;
}
else if(value == e.value)
{
return 0;
}
else 
{
return 1;
}
} 
}

If you are using a boolean value for comparison then simply override the equals method
as

 public boolean equals(Entry e) { 
  return value == e.value;
}

The method is in the Entry class, so you call it using an instance of the Entry class.
Something like

 Entry e = ....... 
if(e.equals(Entry anotherEntry)) {
  //do stuff
}
else {
//do something else
}

calling it in some other class as just equals(e) (like you did with the compareTo) does not make sense and would give incorect results for the equals method and a compilation error for the compareTo method.

[shana07]

Thank you bro...short and clear explanation.
After override with 'equals' and made some adjustment Entry e to Object o (because prompted error something uncompatible Entry - Object...) I got what I want now.

 Object o = ifs.get(4);
        if(o.equals(ifs.get(0)))

Thanks a bunch.......... .
Shana

[r035198x]

Thank you bro...short and clear explanation.
After override with 'equals' and made some adjustment Entry e to Object o (because prompted error something uncompatible Entry - Object...) I got what I want now.

 Object o = ifs.get(4);
if(o.equals(ifs.get(0)))

Thanks a bunch.......... .
Shana

Anytime. It took me a while to understand what you wanted to do there though.

[Ganon11]

Thank you bro...short and clear explanation.
After override with 'equals' and made some adjustment Entry e to Object o (because prompted error something uncompatible Entry - Object...) I got what I want now.

 Object o = ifs.get(4);
        if(o.equals(ifs.get(0)))

Thanks a bunch.......... .
Shana

You may end up having some loss of information when casting to an Object to compare. Instead, you may want to case ifs.get() to Entry, as in:

Entry myEnt = (Entry)ifs.get(4);
if (myEnt.equals((Entry)ifs.get(0))) {
   // And so on...