Question

我开始使用Intellij Idea开发Android应用程序，因为它是去年的首选IDE。我用两个IDE的两个致命错误粉碎了我的脸： Intellij Idea 1.我创建了自定义视图：

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，我试图在Idea中看到UI Designer中的结果：

<?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)

但是在Eclipse（JUNO）的同时，一切都还可以！

然后，我决定使用Eclipse进行开发。我安装它并尝试构建我的项目。但Eclipse告诉我，我使用的是java 1.7，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，但是想法与android和jdk 1.7一起使用!!

有些问题：

为什么我的自定义视图在Eclipse中工作正常，但Idea给了我NPE？
为什么Eclipse无法使用jdk 1.7，但是Idea可以正常使用 jdk 1.7？
我该怎么办？：d
我必须选择哪个IDE？

更新的答案： 因为我声名狼借，我无法回答自己，所以回答问题：我的自定义视图位于com.example.customview.ImageCustomView包中。当我尝试在其他项目中使用它时，我将它放在com.example中并且它工作，而不是重构此视图以命名ImageCustomView，将它移动到com.example并再次工作正常。我试图重复我的错误 - 但是在所有包中都没有成功，它有不同的名称。谢谢！

更新更新： 我重复我的错误。我添加Geasture监听器，使用AttributeSet删除构造函数，然后我再次获得NPE。但是当我放弃所有的变化时 - NPE不会消失。所以我现在不知道什么是错的，所以我需要一些版本或答案。我再次修复它：我将自定义视图类移动到其他包中。

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();

    }

即使我把它添加回来 - NPE也不会消失，但是在这个类的重构名称之后 - 它有效。所以，我的版本是在重构之后刷新预编译类，因为预编译文件是Intellij Idea的功能之一。

经过一些过期后，我有了新的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)

更新了自定义视图：

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construcor - 获得了NPE，重构了类的名称 - 得到了作品，添加了一些更改 - 得到NPE（关于画布，第二个NPE）做重构名称（或地点）的类 - 得到了作品...我不知道... 还有一个细节 - 这个视图对触摸我的图像没有任何反应，断点不会进入方法onTouch ...可能是关键信息。我的目标是在屏幕上移动图像并重新绘制图像，我用手指放置图像。

Answer 1

您的代码对我来说很好（IntelliJ IDEA又称Android Studio）。仔细检查您的项目设置。

Answer 2

Android Studio保存我的屁股。它告诉我错误。所以，关于Eclipse和JDK 1.7我没有答案，但关于Custom视图的答案是：

自定义视图需要两个默认构造函数：

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

    public CustomView(Context context, AttributeSet attrs) {
         super(context, attrs);
    }

onDraw方法必须包含检查null的整个数据：

if (bitmap == null) {
    paint.setStyle(Paint.Style.FILL);
    paint.setColor(Color.CYAN);
    canvas.drawRect(mImagePosition, paint);
    return;
}
Rect rect = new Rect(0, 0, this.getWidth(), this.getHeight());
canvas.drawBitmap(bitmap, rect, mImagePosition, null);

无需制作：
```
super.onDraw(canvas);
```
在onDraw方法中
。

Intellij Idea和Eclipse以及JDK 7和Android

2 个答案: