android - Intellij Idea 和 Eclipse 以及 JDK 7 和 Android

Question

我开始使用 Intellij Idea 为 Android 开发应用程序，因为它是去年的首选 IDE。我用两个 IDE 都犯了两个 fatal error ，把我的脸砸烂了:智能理念1. 我创建了自定义 View :

public class ImageOverlayView extends View implements View.OnTouchListener {

private static final String TAG = "ImageOverlayView";
private Bitmap image;

private float x, y, sX, sY;

private final Paint paint = new Paint();
private float scaleFactor;

private int getScaledWidth()
{
    return (int)(image.getWidth() * scaleFactor);
}

private int getScaledHeight()
{
    return (int)(image.getHeight() * scaleFactor);
}

public ImageOverlayView(Context context) {
    super(context);
}

public ImageOverlayView(Context context, AttributeSet attrs) {
    super(context, attrs);
    TypedArray a = context.obtainStyledAttributes(R.styleable.ImageOverlayView);
    this.setOnTouchListener(this);
}

public void setImage(Bitmap bm) {
    image = bm;
    invalidate();
}

public void setDrawable(Drawable drawable) {
    image = BitmapUtils.drawableToBitmap(drawable);
    invalidate();
}

@Override
public void onDraw(Canvas canvas) {
    super.onDraw(canvas);
    if (canvas != null && image != null) {
        canvas.drawBitmap(image, null, paint);
    } else {
        Log.d(TAG, "Canvas is NULL");
    }
}

@Override
public boolean onTouch(View view, MotionEvent event) {
    switch (event.getAction()) {
        case MotionEvent.ACTION_MOVE: {
            sX = event.getX();
            sY = event.getY();

            break;
        }

    }
    return super.onTouchEvent(event);
}

public void loadImageBitmap(String fileName) {
    BitmapFactory.Options options = new BitmapFactory.Options();
    options.inPreferredConfig = Bitmap.Config.ARGB_8888;

    image = BitmapFactory.decodeFile(fileName, options);
    if (image == null) {
        throw new NullPointerException("The image can't be decoded.");
    }

    scaleFactor = 1;

    // center image on the screen
    int width = getWidth();
    int height = getHeight();
    if ((width != 0) || (height != 0)) {
        int scrollX = (image.getWidth() < width ? -(width - image.getWidth()) / 2 :    image.getWidth() / 2);
        int scrollY = (image.getHeight() < height ? -(height - image.getHeight()) / 2 : image.getHeight() / 2);
        scrollTo(scrollX, scrollY);
    }
    invalidate();
}

public void loadImageDrawable(int resourceId) {
    Resources resources = getResources();
    Drawable drawable = resources.getDrawable(resourceId);
    image = BitmapUtils.drawableToBitmap(drawable);
    invalidate();
}
}

然后，我尝试在 Idea 的 UI Designer 中查看结果:

<?xml version="1.0" encoding="utf-8"?>

<LinearLayout
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    xmlns:android="http://schemas.android.com/apk/res/android">

<ru.lookmyway.customview.ImageOverlayView
    android:id="@+id/imageOverlayView1"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content" />

</LinearLayout>

想法给了我 NPE:

java.lang.NullPointerException
at ru.lookmyway.customview.ImageOverlayView.onDraw(ImageOverlayView.java:65)
at android.view.View.draw(View.java:13712)
at android.view.View.draw(View.java:13596)
at android.view.ViewGroup.drawChild(ViewGroup.java:2928)
at android.view.ViewGroup.dispatchDraw(ViewGroup.java:2797)
at android.view.View.draw(View.java:13594)
at android.view.ViewGroup.drawChild(ViewGroup.java:2928)
at android.view.ViewGroup.dispatchDraw(ViewGroup.java:2797)
at android.view.View.draw(View.java:13594)
at android.view.ViewGroup.drawChild(ViewGroup.java:2928)
at android.view.ViewGroup.dispatchDraw(ViewGroup.java:2797)
at android.view.View.draw(View.java:13715)
at android.view.View.draw(View.java:13596)
at android.view.ViewGroup.drawChild(ViewGroup.java:2928)
at android.view.ViewGroup.dispatchDraw(ViewGroup.java:2797)
at android.view.View.draw(View.java:13715)
at com.android.layoutlib.bridge.impl.RenderSessionImpl.render(RenderSessionImpl.java:570)
at com.android.layoutlib.bridge.Bridge.createSession(Bridge.java:334)
at com.android.ide.common.rendering.LayoutLibrary.createSession(LayoutLibrary.java:325)
at org.jetbrains.android.uipreview.RenderService.createRenderSession(RenderService.java:127)
at org.jetbrains.android.uipreview.RenderUtil.renderLayout(RenderUtil.java:154)
at com.intellij.android.designer.designSurface.AndroidDesignerEditorPanel$8.run(AndroidDesignerEditorPanel.java:346)
at com.intellij.util.ui.update.MergingUpdateQueue.execute(MergingUpdateQueue.java:320)
at com.intellij.util.ui.update.MergingUpdateQueue.execute(MergingUpdateQueue.java:310)
at com.intellij.util.ui.update.MergingUpdateQueue$2.run(MergingUpdateQueue.java:254)
at com.intellij.util.ui.update.MergingUpdateQueue.flush(MergingUpdateQueue.java:269)
at com.intellij.util.ui.update.MergingUpdateQueue.flush(MergingUpdateQueue.java:227)
at com.intellij.util.ui.update.MergingUpdateQueue.run(MergingUpdateQueue.java:217)
at com.intellij.util.Alarm$Request$1.run(Alarm.java:289)
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:471)
at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:334)
at java.util.concurrent.FutureTask.run(FutureTask.java:166)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
at java.lang.Thread.run(Thread.java:722)

但同时在 Eclipse (JUNO) 中一切正常!

然后，我决定使用 Eclipse 进行开发。我安装了它并尝试构建我的项目。但是 Eclipse 告诉我我正在使用 java 1.7，而 Android 需要 5.0 或 6.0。一些谷歌搜索说我不能使用 jdk 1.7 因为在 Android 中还没有支持它，但是 Idea 在 android 和 jdk 1.7 上工作得很好!!

一些问题:

1. 为什么我的自定义 View 在 Eclipse 中工作正常，但 Idea 给我 NPE？
2. 为什么 Eclipse 不能与 jdk 1.7 一起工作，而 Idea 可以与 jdk 1.7 一起工作 jdk 1.7？
3. 我必须做什么？ :D
4. 我必须选择哪个 IDE？

---

更新的答案:由于本人名气不大，无法自答，所以有问题的回答一下:我的自定义 View 在包 com.example.customview.ImageCustomView 中。当我尝试在其他项目中使用它时，我将它放在 com.example 中并且它起作用了，然后我重构了这个 View 以命名 ImageCustomView，将它移动到 com.example 并且它再次工作正常。我试图重复我的错误 - 但在所有包中都没有成功，但它使用不同的名称。谢谢!

---

更新更新:我重复我的错误。我添加了手势监听器，使用 AttributeSet 删除了构造函数，我再次获得了 NPE。但是当我放弃我所有的改变时——NPE 不会消失。所以我现在不知道出了什么问题，所以我需要一些版本或答案。我再次修复它:我将我的自定义 View 类移到其他包中。

---

更多信息:当我删除构造函数时出现 NPE:

    public ImageCustomView(Context context, AttributeSet attrs) {
    super(context, attrs);
    TypedArray a = context.obtainStyledAttributes(R.styleable.ImageCustomView);
    a.recycle();

    }

即使我把它加回去——NPE 也不会消失，但在重构这个类的名称之后——它仍然有效。所以，我的版本是在重构 Idea 后刷新预编译类，因为预编译文件是 Intellij Idea 的功能之一。

过期后我得到了新的 NPE:

java.lang.NullPointerException
at android.graphics.Canvas.throwIfRecycled(Canvas.java:1025)
at android.graphics.Canvas.drawBitmap(Canvas.java:1065)
at ru.lookmyway.ImageCustomView.onDraw(ImageCustomView.java:63)
at android.view.View.draw(View.java:13712)
at android.view.View.draw(View.java:13596)
at android.view.ViewGroup.drawChild(ViewGroup.java:2928)
at android.view.ViewGroup.dispatchDraw(ViewGroup.java:2797)
at android.view.View.draw(View.java:13594)
at android.view.ViewGroup.drawChild(ViewGroup.java:2928)
at android.view.ViewGroup.dispatchDraw(ViewGroup.java:2797)
at android.view.View.draw(View.java:13594)
at android.view.ViewGroup.drawChild(ViewGroup.java:2928)
at android.view.ViewGroup.dispatchDraw(ViewGroup.java:2797)
at android.view.View.draw(View.java:13715)
at android.view.View.draw(View.java:13596)
at android.view.ViewGroup.drawChild(ViewGroup.java:2928)
at android.view.ViewGroup.dispatchDraw(ViewGroup.java:2797)
at android.view.View.draw(View.java:13715)
at com.android.layoutlib.bridge.impl.RenderSessionImpl.render(RenderSessionImpl.java:570)
at com.android.layoutlib.bridge.Bridge.createSession(Bridge.java:334)
at com.android.ide.common.rendering.LayoutLibrary.createSession(LayoutLibrary.java:325)
at org.jetbrains.android.uipreview.RenderService.createRenderSession(RenderService.java:127)
at org.jetbrains.android.uipreview.RenderUtil.renderLayout(RenderUtil.java:154)
at com.intellij.android.designer.designSurface.AndroidDesignerEditorPanel$8.run(AndroidDesignerEditorPanel.java:346)
at com.intellij.util.ui.update.MergingUpdateQueue.execute(MergingUpdateQueue.java:320)
at com.intellij.util.ui.update.MergingUpdateQueue.execute(MergingUpdateQueue.java:310)
at com.intellij.util.ui.update.MergingUpdateQueue$2.run(MergingUpdateQueue.java:254)
at com.intellij.util.ui.update.MergingUpdateQueue.flush(MergingUpdateQueue.java:269)
at com.intellij.util.ui.update.MergingUpdateQueue.flush(MergingUpdateQueue.java:227)
at com.intellij.util.ui.update.MergingUpdateQueue.run(MergingUpdateQueue.java:217)
at com.intellij.util.Alarm$Request$1.run(Alarm.java:289)
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:471)
at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:334)
at java.util.concurrent.FutureTask.run(FutureTask.java:166)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
at java.lang.Thread.run(Thread.java:722)

更新的自定义 View :

public class ImageCustomView extends View implements View.OnTouchListener {

private static final String TAG = "ImageCustomView";
private Bitmap image;

private float x, y, sX, sY;

private final Paint paint = new Paint();
private float scaleFactor;
private GestureDetector gestureDetector;

private int getScaledWidth()
{
    return (int)(image.getWidth() * scaleFactor);
}

private int getScaledHeight()
{
    return (int)(image.getHeight() * scaleFactor);
}

public ImageCustomView(Context context) {
    super(context);
    this.setOnTouchListener(this);
    paint.setFilterBitmap(true);
    paint.setDither(false);
    gestureDetector = new GestureDetector(context, new MyGestureListener());
}

public void setImage(Bitmap bm) {
    image = bm;
    invalidate();
}

public void setDrawable(Drawable drawable) {
    image = BitmapUtils.drawableToBitmap(drawable);
    invalidate();
}

@Override
public void onDraw(Canvas canvas) {
    canvas.drawBitmap(image, 0, 0, paint);
}

@Override
public boolean onTouch(View view, MotionEvent event) {
    switch (event.getAction()) {
        case MotionEvent.ACTION_MOVE: {
            sX = event.getX();
            sY = event.getY();
            Log.d(TAG, "x: " + sX + " y: " + sY);
            break;
        }

    }
    return super.onTouchEvent(event);
}

private class MyGestureListener extends GestureDetector.SimpleOnGestureListener
{
    @Override
    public boolean onScroll(MotionEvent e1, MotionEvent e2, float distanceX, float distanceY)
    {
        scrollBy((int)distanceX, (int)distanceY);
        return true;
    }

    @Override
    public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY)
    {
        int fixedScrollX = 0, fixedScrollY = 0;
        int maxScrollX = getScaledWidth(), maxScrollY = getScaledHeight();

        if (getScaledWidth() < getWidth())
        {
            fixedScrollX = -(getWidth() - getScaledWidth()) / 2;
            maxScrollX = fixedScrollX + getScaledWidth();
        }

        if (getScaledHeight() < getHeight())
        {
            fixedScrollY = -(getHeight() - getScaledHeight()) / 2;
            maxScrollY = fixedScrollY + getScaledHeight();
        }

        boolean scrollBeyondImage = (fixedScrollX < 0) || (fixedScrollX > maxScrollX) || (fixedScrollY < 0) || (fixedScrollY > maxScrollY);
        return !scrollBeyondImage;

    }
}

public void loadImageBitmap(String fileName) {
    BitmapFactory.Options options = new BitmapFactory.Options();
    options.inPreferredConfig = Bitmap.Config.ARGB_8888;

    image = BitmapFactory.decodeFile(fileName, options);
    if (image == null) {
        throw new NullPointerException("The image can't be decoded.");
    }

    scaleFactor = 1;

    // center image on the screen
    int width = getWidth();
    int height = getHeight();
    if ((width != 0) || (height != 0)) {
        int scrollX = (image.getWidth() < width ? -(width - image.getWidth()) / 2 : image.getWidth() / 2);
        int scrollY = (image.getHeight() < height ? -(height - image.getHeight()) / 2 : image.getHeight() / 2);
        scrollTo(scrollX, scrollY);
    }
    invalidate();
}

public void loadImageDrawable(int resourceId) {
    Resources resources = getResources();
    Drawable drawable = resources.getDrawable(resourceId);
    image = BitmapUtils.drawableToBitmap(drawable);
    invalidate();
}

我删除了第二个构造函数 - 得到了 NPE，重构了类的名称 - 得到了工作，添加了一些更改 - 得到了 NPE(关于 Canvas ，第二个 NPE)重构了类的名称(或位置) - 得到了工作......我不知道...还有一个细节——这个 View 对 Touch my image 没有反应，断点不会进入 onTouch 方法……可能是关键信息。我的目标是在屏幕上移动图像并在我用手指放置图像的位置重新绘制图像。

Answer 1

您的代码对我来说工作正常(IntelliJ IDEA 又名 Android Studio)。仔细检查您的项目设置。