java - 安卓 Java |当我调用 setContentView() 时，InflateException 错误导致类膨胀

Question

我是 Android 新手。我正在尝试制作一个简单的应用程序来创建饼图。

我有2个 Activity ，一个是MainActivity，另一个是PieChart，两者都扩展了Activity，并且我有一个扩展了View的MyView类。

在 MainActivity 中，我有一个绑定(bind)到 onClick 事件的按钮(设置为 android:onClick="createPieChart"按钮 XML 属性)，当我单击它时，一个名为“creaTorta()”的函数应该更改 Activity 并创建饼图。

这是MainActivity.java:

public class MainActivity extends Activity {

    private View vista;

    public void creaPieChart(View myView){
       Intent viewPieChart = new Intent(this.getApplicationContext(), PieChart.class);
       startActivity(viewPieChart);

    }

    @Override
    protected void onCreate(Bundle savedInstanceState) {
       super.onCreate(savedInstanceState);
       setContentView(R.layout.activity_main);
       vista= (View)findViewById(R.id.viewtorta1);
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {

     getMenuInflater().inflate(R.menu.main, menu);
     return true;
    }

}

这是饼图 Activity :

 public class PieChart extends Activity {

  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);


    requestWindowFeature(Window.FEATURE_NO_TITLE);
    Log.d("Point", "Here I am!");

            setContentView(R.layout.activity_la_torta);
    Log.d("Point", "Here I am again!");

   }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
    getMenuInflater().inflate(R.menu.la_torta, menu);
    return true;
    }

}

这是 MyView.java:

public class MyView extends View {
  private float cx=0,cy=0;
  private RectF r = new RectF(100,100,430,430);
  private float valori[] = {10,20,10,30,25,5};
      private Paint p,ct;

public MyView(Context context) {
    super(context);
    p=new Paint();
    p.setAntiAlias(true);
    ct=new Paint();
    ct.setAntiAlias(true);
}

   protected void onDraw(Canvas canvas) {
      super.onDraw(canvas);
      canvas.drawColor(Color.BLACK);
      float degStart=0,x,y;
      int i=0;
      ct.setColor(Color.argb(255, 255, 255, 255));
      for (float count : valori){
        float degVal=(float) (count*3.6);
        p.setColor(Color.argb(255, 0, 125, 255-i));
        x=(float)(Math.cos((((degStart-90))*Math.PI)/180)*200)+265 ;
        y=(float)(Math.sin((((degStart-90))*Math.PI)/180)*200)+265;



        canvas.drawArc(r, degStart-90 , degVal, true, p);

        canvas.drawText(""+degVal, x  ,y , ct);

        degStart+=degVal;
        i+=50;
    }
  } 

} 

当我点击按钮时，出现以下错误:致命异常主要java.lang.RuntimeException:无法启动 Activity ComponentInfo()android.view.InflateException:二进制 XML 文件第 18 行:膨胀类 it.adriano.piechart.MyView 时出错

编辑:这是activity_la_torta.xml 文件。当我在 PieChart onCreate() 中调用 setContentView(R.layout.activity_la_torta) 时，应用程序崩溃；

 <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/LinearLayout1"
android:layout_width="300dp"
android:layout_height="500dp"
android:orientation="vertical"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin">

<Button
    android:id="@+id/chiuditorta"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="Button" />

<it.adriano.unatorta.MyView
    android:id="@+id/myView1"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content" />

<View
    android:id="@+id/viewtorta1"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content" />

</LinearLayout>

这是完整的堆栈跟踪(抱歉缩进，如果有更好的方式发布，请告诉我):

03-14 13:41:52.009: E/AndroidRuntime(2189): 
FATAL EXCEPTION: main
03-14 13:41:52.009: E/AndroidRuntime(2189): 
java.lang.RuntimeException: Unable to start activity ComponentInfo{it.adriano.unatorta/it.adriano.unatorta.LaTorta}:
 android.view.InflateException: Binary XML file line #18: 
Error inflating class it.adriano.unatorta.MyView
03-14 13:41:52.009: E/AndroidRuntime(2189):     
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2059)
03-14 13:41:52.009: E/AndroidRuntime(2189):     
at 
android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2084)
03-14 13:41:52.009: E/AndroidRuntime(2189):     
at android.app.ActivityThread.access$600(ActivityThread.java:130)
03-14 13:41:52.009: E/AndroidRuntime(2189):     
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1195)
03-14 13:41:52.009: E/AndroidRuntime(2189):     
at android.os.Handler.dispatchMessage(Handler.java:99)
03-14 13:41:52.009: E/AndroidRuntime(2189):     
at android.os.Looper.loop(Looper.java:137)
03-14 13:41:52.009: E/AndroidRuntime(2189):     
at android.app.ActivityThread.main(ActivityThread.java:4745)
03-14 13:41:52.009: E/AndroidRuntime(2189):     
at java.lang.reflect.Method.invokeNative(Native Method)
03-14 13:41:52.009: E/AndroidRuntime(2189):     
at java.lang.reflect.Method.invoke(Method.java:511)
03-14 13:41:52.009: E/AndroidRuntime(2189):     
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786)
03-14 13:41:52.009: E/AndroidRuntime(2189):     
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
03-14 13:41:52.009: E/AndroidRuntime(2189):     
at dalvik.system.NativeStart.main(Native Method)
03-14 13:41:52.009: E/AndroidRuntime(2189): 
Caused by: android.view.InflateException: Binary XML file line #18: Error inflating class it.adriano.unatorta.MyView
03-14 13:41:52.009: E/AndroidRuntime(2189):     at android.view.LayoutInflater.createView(LayoutInflater.java:596)
03-14 13:41:52.009: E/AndroidRuntime(2189):     at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:687)
03-14 13:41:52.009: E/AndroidRuntime(2189):     at android.view.LayoutInflater.rInflate(LayoutInflater.java:746)
03-14 13:41:52.009: E/AndroidRuntime(2189):     at android.view.LayoutInflater.inflate(LayoutInflater.java:489)
03-14 13:41:52.009: E/AndroidRuntime(2189):     at android.view.LayoutInflater.inflate(LayoutInflater.java:396)
03-14 13:41:52.009: E/AndroidRuntime(2189):     at android.view.LayoutInflater.inflate(LayoutInflater.java:352)
03-14 13:41:52.009: E/AndroidRuntime(2189):     at com.android.internal.policy.impl.PhoneWindow.setContentView(PhoneWindow.java:256)
03-14 13:41:52.009: E/AndroidRuntime(2189):     at android.app.Activity.setContentView(Activity.java:1867)
03-14 13:41:52.009: E/AndroidRuntime(2189):     at it.adriano.unatorta.LaTorta.onCreate(LaTorta.java:21)
03-14 13:41:52.009: E/AndroidRuntime(2189):     at android.app.Activity.performCreate(Activity.java:5008)
03-14 13:41:52.009: E/AndroidRuntime(2189):     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1079)
03-14 13:41:52.009: E/AndroidRuntime(2189):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2023)
03-14 13:41:52.009: E/AndroidRuntime(2189):     ... 11 more
03-14 13:41:52.009: E/AndroidRuntime(2189): Caused by: java.lang.NoSuchMethodException: <init> [class android.content.Context, interface android.util.AttributeSet]
03-14 13:41:52.009: E/AndroidRuntime(2189):     at java.lang.Class.getConstructorOrMethod(Class.java:460)
03-14 13:41:52.009: E/AndroidRuntime(2189):     at java.lang.Class.getConstructor(Class.java:431)
03-14 13:41:52.009: E/AndroidRuntime(2189):     at android.view.LayoutInflater.createView(LayoutInflater.java:561)
03-14 13:41:52.009: E/AndroidRuntime(2189):     ... 22 more

如何解决。我不明白为什么它不启动 startActivity(viewPieChart);适本地。我搞砸了什么？

感谢您的关注。

Answer 1

java.lang.NoSuchMethodException: <init> [class android.content.Context, interface android.util.AttributeSet]

您的 MyView 类没有从 XML 扩充 View 所需的 MyView(Context, AttributeSet) 构造函数重载。

例如，更改当前的构造函数

public MyView(Context context) {
    super(context);
    p=new Paint();
    p.setAntiAlias(true);
    ct=new Paint();
    ct.setAntiAlias(true);
}

使用共享初始化函数的两个必需的构造函数重载:

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

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

private void init() {
    p=new Paint();
    p.setAntiAlias(true);
    ct=new Paint();
    ct.setAntiAlias(true);
}