Question

方法changeFlowers失败，索引超出范围异常。

我是java的新手，我正在调用已经实例化的FishOne（Arraylist可再生类）的方法“changeColor（）” 但它的失败与索引超出范围异常。

public void changeFlowers(int i)
{


        FlowerOne f1 = (FlowerOne)(this._fishes.get(i));   // Is this the right way to call ????
        f1.changeColor(this._theme);


}

Aquarium.java，FishOne.java下面的代码感谢您的帮助。

Aquarium.java，

public class Aquarium {
private AquariumThread _aquariumThread; 
private SurfaceHolder _surfaceHolder;   
private ArrayList<Renderable> _fishes;  
private Bitmap _backgroundImage;
private Context _context;


public void render(){
    Canvas canvas = null;
    try{

        canvas = this._surfaceHolder.lockCanvas(null);
        synchronized (this._surfaceHolder) {
            this.onDraw(canvas);
        }

    }finally{
        if(canvas != null){
            this._surfaceHolder.unlockCanvasAndPost(canvas);
        }
    }   
}


protected void onDraw(Canvas canvas) {
    this.renderBackGround(canvas);
    for (Renderable renderable : this._fishes) {
        renderable.render(canvas);
    }
};

public void initialize(Context context, SurfaceHolder surfaceHolder) {
    this._fishes = new ArrayList<Renderable>();
}



protected void onDraw(Canvas canvas) {
    this.renderBackGround(canvas);
    for (Renderable renderable : this._fishes) {
        renderable.render(canvas);
    }
};


public void start(){
    this._aquariumThread.switchOn();
}


public void stop(){
    boolean retry = true;
    this._aquariumThread.switchOff();
    while (retry) {
        try {
         this._aquariumThread.join();
            retry = false;
        } catch (InterruptedException e) {
            // we will try it again and again...
        }
    }
}


public synchronized void addFishes() {      

Point startPoint1 = new Point(1,300);
this._fishes.add(new fishOne(this._context, this, startPoint1, 90));

Point startPoint2 = new Point(100,300);
this._fishes.add(new fishOne(this._context, this, startPoint2, 90));

Point startPoint3 = new Point(200,300);
this._fishes.add(new fishOne(this._context, this, startPoint3, 90));

}





public void changeFlowers(int i)
{


        FlowerOne f1 = (FlowerOne)(this._fishes.get(i));
        f1.changeColor(this._theme);


}


}

FishOne.java

public class fishOne extends Animal {
private static final int TOTAL_FRAMES_IN_SPRITE = 1;
private static final int CLOWN_FISH_FPS = 1; 

int _fishColor;
Bitmap leftBitmap;
Bitmap rightBitmap;


public fishOne(Context context, Aquarium aquarium,  Point startPoint, int speed){       

    super(context, aquarium);   
    this.changeColor(1);
    this.initialize(this.leftBitmap, this.rightBitmap, CLOWN_FISH_FPS, TOTAL_FRAMES_IN_SPRITE, startPoint, speed);

}


public void changeColor(int mfishColor)
{


    switch(mfishColor) {
    case 1:

    BitmapFactory.Options options = new BitmapFactory.Options();
    options.inPurgeable = true;
    this.leftBitmap = BitmapFactory.decodeResource(getContext().getResources(), com.gotit.livewallpaper.fishshd.R.drawable.fish1, options);

    BitmapFactory.Options options1 = new BitmapFactory.Options();
    options1.inPurgeable = true;
    this.rightBitmap = BitmapFactory.decodeResource(getContext().getResources(), com.gotit.livewallpaper.fishshd.R.drawable.fish2, options1);

        break;

    case 2:
    BitmapFactory.Options options2 = new BitmapFactory.Options();
    options2.inPurgeable = true;
    this.leftBitmap = BitmapFactory.decodeResource(getContext().getResources(), com.gotit.livewallpaper.fishshd.R.drawable.redfish1, options2);

    BitmapFactory.Options options3 = new BitmapFactory.Options();
    options3.inPurgeable = true;
    this.rightBitmap = BitmapFactory.decodeResource(getContext().getResources(), com.gotit.livewallpaper.fishshd.R.drawable.redfish2, options3);

        break;
    default:
    }


}


public void render(Canvas canvas){
    super.render(canvas);   
}

}

Answer 1

这完全取决于代码的错误安全性。基本上如果你确定changeFlowers不会在参数i大于ArrayList大小的情况下调用那么它是Okoteonwise你必须把vheck放在changeFlowers函数中。

喜欢

public void changeFlowers(int i)
{

    if(null!=this._fishes && this._fishes.size()>i){

        FlowerOne f1 = (FlowerOne)(this._fishes.get(i));
        f1.changeColor(this._theme);
}


}

但是，由于存在actulal问题，最好使代码安全，因为这个函数被调用。 上面的代码会停止错误，但您还需要在调用fumction的地方更正。

我的Live壁纸实现中的IndexOutOfBoundsException

Aquarium.java，

FishOne.java

1 个答案: