java - 圆形布局 : Cannot resolve method onCreate(android. os.Bundle)

Question

我想在我的 Android 应用程序中使用 CircularLayout。

我在 MainActivity.java 文件中遇到以下错误:无法解析 onCreate(android.os.Bundle) 方法，即使我已经扩展了 AppCompatActivity。

因为我需要从 AppCompatActivity 和 View 访问方法，所以我使用了嵌套类，错误可能是由于此。不确定如何使用它。我也有以下警告:private inner class Activity is never used。请让我知道延长两个类(class)。我找到了几个答案并使用了它们，包括 Extending from two classes和 How to extend 2 classes?但他们似乎都不适合我。我想知道我可以对我的代码进行哪些更改才能使其正常工作。

这是我的 MainActivity.java 文件的样子:

package com.example.shalini.circlelayout;

import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.RectF;

import android.os.Bundle;
import android.support.design.widget.FloatingActionButton;
import android.support.design.widget.Snackbar;

import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.util.AttributeSet;
import android.view.View;
import android.view.Menu;
import android.view.MenuItem;

public class MainActivity extends AppCompatActivity {
private class Activity extends View {
    private final static int TOTAL_DEGREE = 360;
    private final static int START_DEGREE = -90;

    private Paint mPaint;
    private RectF mOvalRect = null;

    private int mItemCount = 5;
    private int mSweepAngle;

    private int mInnerRadius;
    private int mOuterRadius;
    private Bitmap mCenterIcon;
    private int[] mColors = {Color.RED, Color.YELLOW, Color.GREEN, Color.BLUE, Color.CYAN};
    private String[] mTitles = {"APPT CENTER", "MEDS CABINET", "CHECK-IN", "MY TRACKERS", "MY ACCOUNTS"};


    public Activity(Context context) {
        this(context, null);
    }

    public Activity(Context context, AttributeSet attrs) {
        this(context, attrs, 0);
    }

    public Activity(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);

        mPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
        mPaint.setStrokeWidth(2);

        mSweepAngle = TOTAL_DEGREE / mItemCount;

        mInnerRadius = 125;
        mOuterRadius = 400;

        mCenterIcon = BitmapFactory.decodeResource(getResources(), R.drawable.ic_launcher);
    }

    @Override
    protected void onDraw(Canvas canvas) {

        int width = getWidth();
        int height = getHeight();

        if (mOvalRect == null) {
            mOvalRect = new RectF(width / 2 - mOuterRadius, height / 2 - mOuterRadius, width / 2 + mOuterRadius, height / 2 + mOuterRadius);
        }

        for (int i = 0; i < mItemCount; i++) {
            int startAngle = START_DEGREE + i * mSweepAngle;
            mPaint.setColor(mColors[i]);
            mPaint.setStyle(Paint.Style.FILL);
            canvas.drawArc(mOvalRect, startAngle, mSweepAngle, true, mPaint);

            mPaint.setColor(Color.BLACK);
            mPaint.setStyle(Paint.Style.STROKE);
            canvas.drawArc(mOvalRect, startAngle, mSweepAngle, true, mPaint);

            int centerX = (int) ((mOuterRadius + mInnerRadius) / 2 * Math.cos(Math.toRadians(startAngle + mSweepAngle / 2)));
            int centerY = (int) ((mOuterRadius + mInnerRadius) / 2 * Math.sin(Math.toRadians(startAngle + mSweepAngle / 2)));
            canvas.drawBitmap(mCenterIcon, width / 2 + centerX - mCenterIcon.getWidth() / 2, height / 2 + centerY - mCenterIcon.getHeight() / 2, null);

            mPaint.setColor(Color.BLACK);
            mPaint.setStyle(Paint.Style.FILL);
            canvas.drawText(mTitles[i], width / 2 + centerX - mCenterIcon.getWidth() / 2, height / 2 + centerY + mCenterIcon.getHeight(), mPaint);
        }

        mPaint.setColor(Color.WHITE);
        mPaint.setStyle(Paint.Style.FILL);
        canvas.drawCircle(width / 2, height / 2, mInnerRadius, mPaint);
        canvas.drawBitmap(mCenterIcon, width / 2 - mCenterIcon.getWidth() / 2, height / 2 - mCenterIcon.getHeight() / 2, null);

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

        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);

        FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
        fab.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
                        .setAction("Action", null).show();
            }
        });
    }
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.menu_main, menu);
    return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    // Handle action bar item clicks here. The action bar will
    // automatically handle clicks on the Home/Up button, so long
    // as you specify a parent activity in AndroidManifest.xml.
    int id = item.getItemId();

    //noinspection SimplifiableIfStatement
    if (id == R.id.action_settings) {
        return true;
    }

    return super.onOptionsItemSelected(item);
}
}

这是我的 content_main.xml 文件:

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:custom="http://schemas.android.com/apk/lib/com.google.custom"
xmlns:tools="http://schemas.android.com/tools"
xmlns:app="http://schemas.android.com/apk/res-auto" android:layout_width="match_parent"
android:layout_height="match_parent" android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
android:paddingBottom="@dimen/activity_vertical_margin"
app:layout_behavior="@string/appbar_scrolling_view_behavior"
tools:showIn="@layout/activity_main" tools:context=".MainActivity">
<com.example.shalini.circlelayout.MainActivity.Activity
android:id="@+id/pie"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="@android:color/white"
custom:dividerWidth="5dp"
custom:innerCircle="@drawable/profile_pic_icon"
custom:innerRadius="50dp"
custom:layoutMode="pie"
custom:sliceDivider="@android:color/transparent" >

<RelativeLayout
    android:id="@+id/appt_center_container"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:background="@drawable/ic_launcher1" >

    <TextView
        android:id="@+id/one"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:gravity="center"

        android:text="@string/appcenter"
        android:textStyle="bold" />
</RelativeLayout>

<RelativeLayout
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:background="@drawable/ic_launcher2" >

    <TextView
        android:id="@+id/two"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:gravity="center"

        android:text="@string/medscabinet"
        android:textStyle="bold" />
</RelativeLayout>

<RelativeLayout
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:background="@drawable/ic_launcher3" >

    <TextView
        android:id="@+id/three"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:gravity="center"

        android:text="@string/cjeckin"
        android:textStyle="bold" />
</RelativeLayout>

<RelativeLayout
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:background="@drawable/ic_launcher4" >

    <TextView
        android:id="@+id/four"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:gravity="center"

        android:text="@string/mytrackers"
        android:textStyle="bold" />
</RelativeLayout>

<RelativeLayout
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:background="@drawable/ic_launcher5" >

    <TextView
        android:id="@+id/five"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:gravity="center"

        android:text="@string/myaccounts"
        android:textStyle="bold" />
</RelativeLayout>
</com.example.shalini.circlelayout.MainActivity.Activity>

</RelativeLayout>

Answer 1

1. 我想建议您以更有意义的方式调用 View 的子类。在你的情况下

   私有(private)类 Activity 扩展 View {

2. 关于 onCreate，这是您怀疑的来源，您将它放在了 View 的子类中。由于 View 没有名为 onCreate 的方法，因此编译器会报错。解决方案是将方法及其内容移动到外部类中，即 extends Activity

3. 您的 View 子类是内部的和私有(private)的。我怀疑您是否能够在您的 xml 中引用它