Reducing imageview buttons code

Question

This code is very long, and you need a separate method. How can I implement it?

I have 6 (x2) imageview buttons and 6 edittext.

public void onClick(View v) {
        // TODO Auto-generated method stub
        switch (v.getId())
        {
        case R.id.imageViewPlusSubEdit1:
            if(editTextInputNameSubEdit1.getText().toString().trim().length() == 0)
            {
                Toast.makeText(this, "Empty text!", Toast.LENGTH_SHORT).show();
            }
            else if(items1.size() > 23)
            {
                Toast.makeText(this, "Too many elements!", Toast.LENGTH_SHORT).show();
            }
            else
            {       
                items1.add(editTextInputNameSubEdit1.getText().toString());
                adapterList1.notifyDataSetChanged(); 
                editTextInputNameSubEdit1.setText("");
            }
            break;
        case R.id.imageViewMinusSubEdit1:
            SparseBooleanArray checkedItemPositions = listViewSubEdit1.getCheckedItemPositions();
            int itemCount = listViewSubEdit1.getCount();
            for(int i = itemCount - 1; i >= 0; i--)
            {
                if(checkedItemPositions.get(i))
                {
                    adapterList1.remove(items1.get(i));
                }
            }
            checkedItemPositions.clear();
            adapterList1.notifyDataSetChanged(); 
            break;

        case R.id.imageViewPlusSubEdit2:
            if(editTextInputNameSubEdit2.getText().toString().trim().length() == 0)
            {
                Toast.makeText(this, "Empty text!", Toast.LENGTH_SHORT).show();
            }
            else if(items2.size() > 23)
            {
                Toast.makeText(this, "Too many elements!", Toast.LENGTH_SHORT).show();
            }
            else
            {       
                items2.add(editTextInputNameSubEdit2.getText().toString());
                adapterList2.notifyDataSetChanged(); 
                editTextInputNameSubEdit2.setText("");
            }
            break;
        case R.id.imageViewMinusSubEdit2:
            SparseBooleanArray checkedItemPositions2 = listViewSubEdit2.getCheckedItemPositions();
            int itemCount2 = listViewSubEdit2.getCount();
            for(int i = itemCount2 - 1; i >= 0; i--)
            {
                if(checkedItemPositions2.get(i))
                {
                    adapterList2.remove(items2.get(i));
                }
            }
            checkedItemPositions2.clear();
            adapterList2.notifyDataSetChanged(); 
            break;

        case R.id.imageViewPlusSubEdit3:
            if(editTextInputNameSubEdit3.getText().toString().trim().length() == 0)
            {
                Toast.makeText(this, "Empty text!", Toast.LENGTH_SHORT).show();
            }
            else if(items3.size() > 23)
            {
                Toast.makeText(this, "Too many elements!", Toast.LENGTH_SHORT).show();
            }
            else
            {       
                items3.add(editTextInputNameSubEdit3.getText().toString());
                adapterList3.notifyDataSetChanged(); 
                editTextInputNameSubEdit3.setText("");
            }
            break;
        case R.id.imageViewMinusSubEdit3:
            SparseBooleanArray checkedItemPositions3 = listViewSubEdit3.getCheckedItemPositions();
            int itemCount3 = listViewSubEdit3.getCount();
            for(int i = itemCount3 - 1; i >= 0; i--)
            {
                if(checkedItemPositions3.get(i))
                {
                    adapterList3.remove(items3.get(i));
                }
            }
            checkedItemPositions3.clear();
            adapterList3.notifyDataSetChanged(); 
            break;

        case R.id.imageViewPlusSubEdit4:
            if(editTextInputNameSubEdit4.getText().toString().trim().length() == 0)
            {
                Toast.makeText(this, "Empty text!", Toast.LENGTH_SHORT).show();
            }
            else if(items4.size() > 23)
            {
                Toast.makeText(this, "Too many elements!", Toast.LENGTH_SHORT).show();
            }
            else
            {       
                items4.add(editTextInputNameSubEdit4.getText().toString());
                adapterList4.notifyDataSetChanged(); 
                editTextInputNameSubEdit4.setText("");
            }
            break;
        case R.id.imageViewMinusSubEdit4:
            SparseBooleanArray checkedItemPositions4 = listViewSubEdit4.getCheckedItemPositions();
            int itemCount4 = listViewSubEdit4.getCount();
            for(int i = itemCount4 - 1; i >= 0; i--)
            {
                if(checkedItemPositions4.get(i))
                {
                    adapterList4.remove(items4.get(i));
                }
            }
            checkedItemPositions4.clear();
            adapterList4.notifyDataSetChanged(); 
            break;

        case R.id.imageViewPlusSubEdit5:
            if(editTextInputNameSubEdit5.getText().toString().trim().length() == 0)
            {
                Toast.makeText(this, "Empty text!", Toast.LENGTH_SHORT).show();
            }
            else if(items5.size() > 23)
            {
                Toast.makeText(this, "Too many elements!", Toast.LENGTH_SHORT).show();
            }
            else
            {       
                items5.add(editTextInputNameSubEdit5.getText().toString());
                adapterList5.notifyDataSetChanged(); 
                editTextInputNameSubEdit5.setText("");
            }
            break;
        case R.id.imageViewMinusSubEdit5:
            SparseBooleanArray checkedItemPositions5 = listViewSubEdit5.getCheckedItemPositions();
            int itemCount5 = listViewSubEdit5.getCount();
            for(int i = itemCount5 - 1; i >= 0; i--)
            {
                if(checkedItemPositions5.get(i))
                {
                    adapterList5.remove(items5.get(i));
                }
            }
            checkedItemPositions5.clear();
            adapterList5.notifyDataSetChanged(); 
            break;

        case R.id.imageViewPlusSubEdit6:
            if(editTextInputNameSubEdit6.getText().toString().trim().length() == 0)
            {
                Toast.makeText(this, "Empty text!", Toast.LENGTH_SHORT).show();
            }
            else if(items6.size() > 23)
            {
                Toast.makeText(this, "Too many elements!", Toast.LENGTH_SHORT).show();
            }
            else
            {       
                items6.add(editTextInputNameSubEdit6.getText().toString());
                adapterList6.notifyDataSetChanged(); 
                editTextInputNameSubEdit6.setText("");
            }
            break;
        case R.id.imageViewMinusSubEdit6:
            SparseBooleanArray checkedItemPositions6 = listViewSubEdit6.getCheckedItemPositions();
            int itemCount6 = listViewSubEdit6.getCount();
            for(int i = itemCount6 - 1; i >= 0; i--)
            {
                if(checkedItemPositions6.get(i))
                {
                    adapterList6.remove(items6.get(i));
                }
            }
            checkedItemPositions6.clear();
            adapterList6.notifyDataSetChanged(); 
            break;
        }

Answer 1

Step #1: create a function for the body of each case in your switch statement

public void onClick(View v) {
    // TODO Auto-generated method stub
    switch (v.getId())
    {
        case R.id.imageViewPlusSubEdit1:
            handleImageViewPlusSubEdit1();
            break;
        case R.id.imageViewMinusSubEdit1:
            handleImageViewMinusSubEdit1();
            break;
        ...
    }
}

Step #2: create your own click handler interface - or re-use the existing one

interface ClickHandler {
    void onClick();
}

Step #3: create specific classes for each of the different ways that you handle the clicks. For example:

class PlusClickHander implements ClickHandler {
    public void onClick() {
        handleImageViewPlusSubEdit1();
    }
}

Step #4: replace the switch statements that directly call the functions, with calls to the ClickHandlers

public void onClick(View v) {
    // TODO Auto-generated method stub
    switch (v.getId())
    {
        case R.id.imageViewPlusSubEdit1:
            ClickHandler plusClickHandler = new PlusClickHandler();
            plusClickHandler.onClick();
            break;
        case R.id.imageViewMinusSubEdit1:
            ClickHandler minusClickHandler = new MinusClickHandler();
            minusClickHandler.onClick();
            break;
        ...
    }
}

Step #5: move the click handlers into a Map, so that you can look them up.

public void onClick(View v) {
    Map<Id,ClickHandler> handlers = new HashMap<Id,ClickHandler>();
    handlers.put(R.id.imageViewPlusSubEdit1, new PlusClickHandler();
    handlers.put(R.id.imageViewMinusSubEdit1, new MinusClickHandler();
    ...

    ClickHandler clickHandler = handlers.get(v.getId());
    clickHandler.onClick();
}

Step #6: create a new function to get the map you need

public Map<Id,ClickHandler> createHandlers() {

    Map<Id,ClickHandler> handlers = new HashMap<Id,ClickHandler>();
    handlers.put(R.id.imageViewPlusSubEdit1, new PlusClickHandler();
    handlers.put(R.id.imageViewMinusSubEdit1, new MinusClickHandler();
    ...
    return handlers;
}

public void onClick(View v) {
    Map<Id,ClickHandler> handlers = createHandlers();

    ClickHandler clickHandler = handlers.get(v.getId());
    clickHandler.onClick();
}

Here's an example of what PlusClickHandler might look like...

public class PlusClickHandler implements ClickHandler {
    private final ? editTextInput;
    private final ? items;
    private final ? adapterList;

    private final int itemLimit = 23;

    public PlusClickHandler(...) {
        editTextInput = ?
        items = ?
        adapterList = ?
    }

    public void onClick() {

        String input = editTextInput.getText().toString();

        if(input.isEmpty())
        {
            Toast.makeText(this, "Empty text!", Toast.LENGTH_SHORT).show();
        }
        else if(items.size() > itemLimit)
        {
            Toast.makeText(this, "Too many elements!", Toast.LENGTH_SHORT).show();
        }
        else
        {       
            items.add(input);
            adapterList.notifyDataSetChanged(); 
            editTextInput.setText("");
        }
    }
}