Java--What is wrong with my code?

jeriffstive · **Posted:** Wed Nov 03, 2010 8:47 pm

2 parts of my assignment are failing junit tests and i dont know why, hoping someone on here can fix them. First part basicallyreturns the element whos position in the list matches the parameter. Second part returns true if the parameter is in the list, false if parameter is not. I know it must be a small logical error in both.

First part code

Code:

public int getAt(int index) {
if (index<0 || index>values[(values.length-1)]){
throw new IndexOutOfBoundsException();
}
int retValue = 0;
for(int i =0; i<values.length; i++){
if(values[i]==index){
retValue = values[index];
}
}
return retValue;
}

Second Part Code

Code:

public boolean contains(int number) {
boolean retValue = false;
for(int i =0; i<values.length-1; i++){
if(values[i]==number){
retValue = true;
}else{
retValue = false;
}
}
return retValue;
}

msi_333 · **Posted:** Wed Nov 03, 2010 11:53 pm

hi brother ,
to get element using index i think the function should be like this :

Code:

public int getAt(int index) {
if (index<0 || index>(values.length-1)){
throw new IndexOutOfBoundsException();
}
int retValue = 0;
for(int i =0; i<values.length; i++){
if(i==index){
retValue = values[index];
}
}
return retValue;
}
 

apeter · **Posted:** Thu Nov 04, 2010 7:59 am

Hello jeriffstive,

it's quite clear that the second code isn't working like expected.

You are iterating over the whole array using a for-loop. Inside the loop you are testing, if the value at position i is equal to the value number. But if you hit the position you don't stop iterating and thats the problem.

Example: your array values contains {1, 3, 5} and you are looking for 3. Your for-loop iterates the three values 1, 3 and 5. The variable retVal will have the following values:
for i=0, values[0]=1: retVal = false
for i=1, values[1]=3: retVal = true
for i=2, values[2]=5: retVal = false
and your function will return false.

You have to stop your searching, when you find the element. The correct code would be:

Code:

   public boolean contains(int number) {
      for(int i = 0; i < values.length - 1; i++){
         if(values[i] == number){
            return true;
         }
      }
      return false;
   }   

Java--What is wrong with my code?

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