4 7 - 4 Developing Algorithms using ArrayLists

Adding an element while traversing

public void addElem(ArrayList<Type> list) {
	for(int index = 0; index < list.size() ; index++){
		//condition for adding element
			list.add(index+1,element);
			index++;
	}
}

so if number is odd add number + 2 after number?

public void addElem(ArrayList<Type> list) {
	int element = list.get(index);
	for(int index = 0; index < list.size() ; index++){
		if(elem % 2 == 1)
			list.add(index+1,element + 2);
			index++;
	}
}

ArrayLists have some common algorithms depending on datatype:

• Determine a minimum sum or maximum value
• Compute a sum, average, or mode
• Determine if at least one element has a particular property
• Access all consecutive pairs of elements
• Determine the presence or absence of duplicate elements
• Determine the number of elements meeting specific criteria
• Shift or rotate elements left or right
• Reverse the order of elements

in order to: * Determine a minimum sum or maximum value * Compute a sum, average, or mode

we:

Arraylist<Integer> scores = new ArrayList<Integer>();
 
//initialize value here 
 
for (int i = 0; i < scores.size(); i++){
	//perform calculation here
}
//report results here 

in order to:

• Determine if at least one element has a particular property
• Determine if all elements have a particular property
• Determine the number of elements meeting specific criteria

we:

ArrayList<String> grades = new ArrayList<String>();
 
//initialize tracker variable
 
for(int i = 0; i < grades.size; i++){
	//conditionally check properties
}
//report results here
 

In order to:

• Shift or rotate elements left or right
• Reverse the order of elements

we:

ArrayList<String> grades = new ArrayList<String>();
ArrayList<String> alteredArray = new ArrayList<String>();
 
for (int i = 0; i < grades.size(); i++){
	//add values from grade to alteredArray
}
//report results here 

in order to sum indicies of two arrays:

ArrayList<Integer> summedList = new ArrayList<Integer>();
for(int index = 0; index < list1.size(); index++) {
	int sum = list1.get(index) + list2.get(index);
	summedList.add(sum);
}
return summedList;