Java引用单个ArrayList实例

Question

I have encountered a problem with the ArrayList I'm using. This is a list of objects containing sprites with a color and location that differ from each other. The list is returned successfully and I can use a foreach loop to draw them all to the screen. After that I am checking if someone has clicked on their location and I want to return the color that the object contains. The problem is I always get the color green back. Probably because I reference to all the objects instead of a single one. I have searched through this site and found similar problems and tutorials. But I can not seem to find the information I need to fix the code so that I can reference to a single instance in the list while using a foreach loop to check them all.

After reading the answers and using break and the forgotten secondColor = true, I still have the same problem. Even when sending the clicked object to another function my problem is not solved. So instead of only showing the code for reading out the list I show the code for when the list is filled as well. How can I fix that I only refer to the green object at all times when reading the list but when using the for loop to draw I get every color????

for(KleurWissel i : gameManager.getColorsList())
        {
            i.colorRectangle.draw(batch);
        }
        //Welke kleuren kies je?
        if(Gdx.input.isButtonPressed(Input.Buttons.LEFT)){
            Iterator<KleurWissel> iterator = gameManager.getColorsList().iterator(); 
            while(iterator.hasNext()) 
            {
                KleurWissel item = (KleurWissel) iterator.next();

                if(item.getRectangle().contains(input.x, input.y)) 
                { 
                    if(firstColor == true && secondColor == false && item.selected == false)
                    {
                        colorArraySecond = item.colorArray;
                        colorArrayUsed = colorArrayFirst;
                        colorSelected = true;
                        item.selected = true;
                        secondColor = true;
                        break;
                    }
                    if(firstColor == false && item.selected == false){
                        colorArrayFirst = item.colorArray;
                        firstColor = true;
                        item.selected = true;
                        break;
                    }
                }
            }  
        }

And here the code for filling the list.

private int[] colorsRGB = {0, 50, 150, 150, 200, 255};
float[] colorArrayUsed = new float[4];
private ArrayList<KleurWissel> colorsList = new ArrayList<KleurWissel>();


public void setColorsList()
{
    Vector2 tempV;
    KleurWissel temp;
    for(int i = 0; i < 6; i++)
    {
        if(i<3)
        {
            colorArrayUsed[0] = colorsRGB[5-i];
            colorArrayUsed[1] = colorsRGB[0+i];
            colorArrayUsed[2] = 0;
            colorArrayUsed[3] = 1;
            tempV = new Vector2(Gdx.graphics.getWidth()/2 - 150 + i * 150, Gdx.graphics.getHeight()/2 + 130);
        }
        else{
            if(i == 3)
            {
                colorArrayUsed[0] = 0;
                colorArrayUsed[1] = 0;
                colorArrayUsed[2] = colorsRGB[5];
                colorArrayUsed[3] = 1;
                tempV = new Vector2(Gdx.graphics.getWidth()/2 - 150, Gdx.graphics.getHeight()/2);
            }
            else{
                colorArrayUsed[0] = 0;
                colorArrayUsed[1] = colorsRGB[0+i];
                colorArrayUsed[2] = colorsRGB[5-i];
                colorArrayUsed[3] = 1;
                tempV = new Vector2(Gdx.graphics.getWidth()/2 - 600 + i * 150, Gdx.graphics.getHeight()/2);
            }

        }
        temp = new KleurWissel(colorArrayUsed, tempV);

        colorsList.add(temp);
    }
}

public ArrayList<KleurWissel> getColorsList()
{
    return colorsList;
}

KleurWissel is the color object, sorry for the bit of Dutch >.>.

Answer 1

Edited based on the comments:

The libGDX Rectangle class has a contains method, and it seems like this is what you are checking there manually. You could also print some information that tells you more about whether an object was hit or not.

It seems like the intended process is the following:

• When the first item is clicked, its color should be stored as colorArrayFirst
• When the second item is clicked, its color should be stored as colorArraySecond , and the colorSelected flag should be set to true

The followign code shows how this could be done. But the question still when this information will be "reset". That is, when will both arrays be reset to null , and when will the colorSelected flag be reset to false ?

private boolean colorSelected = false;
private int colorArrayFirst[] = null;
private int colorArraySecond[] = null;

void someGameLoopMethod()
{
    if(Gdx.input.isButtonPressed(Input.Buttons.LEFT))
    {
        Iterator<ColorObject> iterator = gameManager.getColorsList().iterator();
        while(iterator.hasNext())
        {
            ColorObject item = (ColorObject) iterator.next();

            float x = Gdx.input.getX();
            float y = Gdx.input.getY();
            Rectangle r = item.colorRectangle;

            System.out.println("Check if "+x+" "+y+" is in "+r+": "+r.contains(x,y));

            if (r.contains(x,y))
            {
                clickedItem(item);
            }
        }
    }
}


private void clickedItem(ColorObject item)
{
    if (colorArrayFirst == null)
    {
        colorArrayFirst = item.colorArray;
    }
    else if (colorArraySecond == null)
    {
        colorArraySecond = item.colorArray;
        colorSelected = true;
    }
}

// TODO Think about when this method should be called
private void resetClickingInformation()
{
    colorSelected = false;
    colorArrayFirst = null;
    colorArraySecond = null;
}

Answer 2

The logic in your original question is fine, except that you need to add either

secondColor = true;
break;

inside the block with if(firstColor == true && secondColor == false) .

If you don't do this, then after you set the second colour, you will keep iterating through the ColorObject objects, looking for more of them that include the point that was clicked, until eventually, you get to the last one - which presumably spans the whole canvas and has green as its colour.

The break; isn't strictly necessary, but it saves you from having redundant iterations.