android - 为自定义 View 创建 View 时出错

Question

我创建了一个采用路径的自定义 View 类，然后将其填充为白色并将其边缘着色为红色:

StrokeFill.java:

package com.kf.pathshape;
...

public class StrokeFill extends View{
private Path shapePath;

public StrokeFill(Context context, Path path) {
    super(context);
    this.shapePath = path;

    // TODO Auto-generated constructor stub
}

public StrokeFill(Context context, AttributeSet attrs, Path shapePath) {
    super(context, attrs);
    this.shapePath = shapePath;
}

protected void onDraw(Canvas canvas) {
    // TODO Auto-generated method stub
    //canvas.drawColor(Color.BLACK);
    super.onDraw(canvas);

    //Sets paints and draws the shapes
    Paint fillPaint = new Paint();
    fillPaint.setColor(android.graphics.Color.WHITE);
    fillPaint.setStyle(Paint.Style.FILL);
    fillPaint.setStrokeWidth(0);
    Paint strokePaint = new Paint();
    strokePaint.setColor(android.graphics.Color.RED);
    strokePaint.setStyle(Paint.Style.STROKE);
    strokePaint.setStrokeWidth(2);

    canvas.drawPath(shapePath, fillPaint);
    canvas.drawPath(shapePath, strokePaint);
}
}

我的布局 XML (main.xml) 非常简单:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical" >
<com.kf.pathshape.StrokeFill
    android:id="@+id/pathshape"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content" />
</LinearLayout>

Activity :

setContentView(R.layout.main);
shapeView = (StrokeFill) findViewById(R.id.pathshape);
shapeView = new StrokeFill(this, testpath);

测试路径是一个有效的路径。即使我注释掉定义“shapeView”的行，它也会给我错误。日志:

07-11 01:50:17.150: E/AndroidRuntime(24321): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.kf.pathshape/com.kf.pathshape.PathshapeActivity}: android.view.InflateException: Binary XML file line #6: Error inflating class com.kf.pathshape.StrokeFill
07-11 01:50:17.150: E/AndroidRuntime(24321):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1651)
07-11 01:50:17.150: E/AndroidRuntime(24321):    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1667)
07-11 01:50:17.150: E/AndroidRuntime(24321):    at android.app.ActivityThread.access$1500(ActivityThread.java:117)
07-11 01:50:17.150: E/AndroidRuntime(24321):    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:935)
07-11 01:50:17.150: E/AndroidRuntime(24321):    at android.os.Handler.dispatchMessage(Handler.java:99)
07-11 01:50:17.150: E/AndroidRuntime(24321):    at android.os.Looper.loop(Looper.java:130)
07-11 01:50:17.150: E/AndroidRuntime(24321):    at android.app.ActivityThread.main(ActivityThread.java:3691)
07-11 01:50:17.150: E/AndroidRuntime(24321):    at java.lang.reflect.Method.invokeNative(Native Method)
07-11 01:50:17.150: E/AndroidRuntime(24321):    at java.lang.reflect.Method.invoke(Method.java:507)
07-11 01:50:17.150: E/AndroidRuntime(24321):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:912)
07-11 01:50:17.150: E/AndroidRuntime(24321):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:670)
07-11 01:50:17.150: E/AndroidRuntime(24321):    at dalvik.system.NativeStart.main(Native Method)
07-11 01:50:17.150: E/AndroidRuntime(24321): Caused by: android.view.InflateException: Binary XML file line #6: Error inflating class com.kf.pathshape.StrokeFill
07-11 01:50:17.150: E/AndroidRuntime(24321):    at android.view.LayoutInflater.createView(LayoutInflater.java:508)
07-11 01:50:17.150: E/AndroidRuntime(24321):    at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:570)
07-11 01:50:17.150: E/AndroidRuntime(24321):    at android.view.LayoutInflater.rInflate(LayoutInflater.java:623)
07-11 01:50:17.150: E/AndroidRuntime(24321):    at android.view.LayoutInflater.inflate(LayoutInflater.java:408)
07-11 01:50:17.150: E/AndroidRuntime(24321):    at android.view.LayoutInflater.inflate(LayoutInflater.java:320)
07-11 01:50:17.150: E/AndroidRuntime(24321):    at android.view.LayoutInflater.inflate(LayoutInflater.java:276)
07-11 01:50:17.150: E/AndroidRuntime(24321):    at com.android.internal.policy.impl.PhoneWindow.setContentView(PhoneWindow.java:234)
07-11 01:50:17.150: E/AndroidRuntime(24321):    at android.app.Activity.setContentView(Activity.java:1679)
07-11 01:50:17.150: E/AndroidRuntime(24321):    at com.kf.pathshape.PathshapeActivity.onCreate(PathshapeActivity.java:73)
07-11 01:50:17.150: E/AndroidRuntime(24321):    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1050)
07-11 01:50:17.150: E/AndroidRuntime(24321):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1615)
07-11 01:50:17.150: E/AndroidRuntime(24321):    ... 11 more
07-11 01:50:17.150: E/AndroidRuntime(24321): Caused by: java.lang.NoSuchMethodException: StrokeFill(Context,AttributeSet)

我在论坛中进行了搜索，但没有找到我需要的内容。我已经定义了采用上下文和属性的构造函数。我在这里缺少什么？

Answer 1

在扩展 View 时，您需要实现 3 个构造函数:

public class StrokeFill extends View{
    private Path mShapePath;

    public StrokeFill(Context context) {
        super(context);
        init();
    }

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

    public StrokeFill(Context context, AttributeSet attrs, int defstyle) {
        super(context, attrs, defstyle);
        init();
    }

    private void init(){
        //some code... or not =)
    }

    public void setPath(Path path){
        mShapePath = path;
    }
    /* rest of your code */
}

然后在你的 Activity 中:

shapeView = (StrokeFill) findViewById(R.id.pathshape);
shapeView.setPath(yourPath);

希望对你有帮助