java - Android 自定义 View 不起作用

Question

我正在尝试绘制折线图。准确地说，我成功了，但是当我想在 Activity 中显示此 View 时，我收到错误(无法解释的错误)，我使用 android studio 和这里的所有代码。

我的 Activity 从未加载。抛出错误。

查看类；

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Point;
import android.view.Display;
import android.view.View;
import android.view.WindowManager;
import android.widget.Toast;

import java.security.PublicKey;

public class DwarView extends View {

public int[]yuzde; //im getting some values

Paint paint = new Paint();
Paint paint2 = new Paint(); //my paints for drawing
Paint paint3 = new Paint();


public DwarView(Context context) {
    super(context);
    paint.setStrokeWidth(6f);
    paint.setColor(Color.BLACK);
    paint2.setStrokeWidth(3f);
    paint2.setColor(Color.BLUE);
    paint3.setColor(Color.LTGRAY);
    paint3.setStrokeWidth(2f);
}

private float Hesapla(int Yuzde)
{
    float sonuc;
    sonuc = 500-(500*Yuzde)/100;
    return sonuc;
}

@Override
public void onDraw(Canvas canvas)
{
    super.onDraw(canvas);
    WindowManager wm = (WindowManager)getContext().getSystemService(Context.WINDOW_SERVICE);
    Display ekran = wm.getDefaultDisplay();
    Point olcu = new Point();
    ekran.getSize(olcu);
    int genislik = olcu.x;
    int yukseklik = olcu.y;
    int row = olcu.x/12;

    canvas.drawLine(row,0,row,500,paint3);
    canvas.drawLine(row*2,0,row*2,500,paint3);
    canvas.drawLine(row*3,0,row*3,500,paint3);
    canvas.drawLine(row*4,0,row*4,500,paint3);
    canvas.drawLine(row*5,0,row*5,500,paint3);
    canvas.drawLine(row*6,0,row*6,500,paint3);
    canvas.drawLine(row*7,0,row*7,500,paint3);
    canvas.drawLine(row*8,0,row*8,500,paint3);
    canvas.drawLine(row*9,0,row*9,500,paint3);
    canvas.drawLine(row*10,0,row*10,500,paint3);
    canvas.drawLine(row*11,0,row*11,500,paint3);

    canvas.drawLine(0,100,genislik,100,paint3);
    canvas.drawLine(0,200,genislik,200,paint3);
    canvas.drawLine(0,300,genislik,300,paint3);
    canvas.drawLine(0,400,genislik,400,paint3);

    canvas.drawLine(0,500,row,Hesapla(yuzde[0]),paint2);
    canvas.drawLine(row,Hesapla(yuzde[0]),row*2,Hesapla(yuzde[1]),paint2);
    canvas.drawLine(row*2,Hesapla(yuzde[1]),row*3,Hesapla(yuzde[2]),paint2);
    canvas.drawLine(row*3,Hesapla(yuzde[2]),row*4,Hesapla(yuzde[3]),paint2);
    canvas.drawLine(row*4,Hesapla(yuzde[3]),row*5,Hesapla(yuzde[4]),paint2);
    canvas.drawLine(row*5,Hesapla(yuzde[4]),row*6,Hesapla(yuzde[5]),paint2);
    canvas.drawLine(row*6,Hesapla(yuzde[5]),row*7,Hesapla(yuzde[6]),paint2);
    canvas.drawLine(row*7,Hesapla(yuzde[6]),row*8,Hesapla(yuzde[7]),paint2);
    canvas.drawLine(row*8,Hesapla(yuzde[7]),row*9,Hesapla(yuzde[8]),paint2);
    canvas.drawLine(row*9,Hesapla(yuzde[8]),row*10,Hesapla(yuzde[9]),paint2);
    canvas.drawLine(row*10,Hesapla(yuzde[9]),row*11,Hesapla(yuzde[10]),paint2);
    canvas.drawLine(row*11,Hesapla(yuzde[10]),row*12,Hesapla(yuzde[11]),paint2);
    canvas.drawLine(0,500,genislik,500,paint);


    }
}

主要 Activity ；

import android.graphics.Color;
import android.support.v7.app.ActionBarActivity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;


public class MainActivity extends ActionBarActivity {

    DwarView drawView;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        drawView = new DwarView(this);
        drawView.setBackgroundColor(Color.WHITE);
        drawView.yuzde = new int[] {10,50,60,30,70,100,50,80,90,10,30,50};
        setContentView(R.layout.activity_main);
    }
}

主要 Activity 设计 Xml；

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools" 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" tools:context=".MainActivity">
    <com.adjans.huskerr.acharttest.DwarView
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"/>


</RelativeLayout>

AndroidManifest 文件；

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.adjans.huskerr.acharttest" >

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" >
        <activity
            android:name=".MainActivity"
            android:label="@string/app_name" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>

LogCat 日志；

24 11:48:18.236  23544-23544/com.adjans.huskerr.acharttest D/dalvikvm﹕ VFY: replacing opcode 0x6f at 0x0000
02-24 11:48:18.236  23544-23544/com.adjans.huskerr.acharttest I/dalvikvm﹕ Could not find method android.support.v7.internal.widget.ActionBarOverlayLayout.stopNestedScroll, referenced from method android.support.v7.internal.widget.ActionBarOverlayLayout.setHideOnContentScrollEnabled
02-24 11:48:18.236  23544-23544/com.adjans.huskerr.acharttest W/dalvikvm﹕ VFY: unable to resolve virtual method 9082: Landroid/support/v7/internal/widget/ActionBarOverlayLayout;.stopNestedScroll ()V
02-24 11:48:18.236  23544-23544/com.adjans.huskerr.acharttest D/dalvikvm﹕ VFY: replacing opcode 0x6e at 0x000e
02-24 11:48:18.241  23544-23544/com.adjans.huskerr.acharttest I/dalvikvm﹕ Could not find method android.content.res.TypedArray.getChangingConfigurations, referenced from method android.support.v7.internal.widget.TintTypedArray.getChangingConfigurations
02-24 11:48:18.241  23544-23544/com.adjans.huskerr.acharttest W/dalvikvm﹕ VFY: unable to resolve virtual method 366: Landroid/content/res/TypedArray;.getChangingConfigurations ()I
02-24 11:48:18.241  23544-23544/com.adjans.huskerr.acharttest D/dalvikvm﹕ VFY: replacing opcode 0x6e at 0x0002
02-24 11:48:18.246  23544-23544/com.adjans.huskerr.acharttest I/dalvikvm﹕ Could not find method android.content.res.TypedArray.getType, referenced from method android.support.v7.internal.widget.TintTypedArray.getType
02-24 11:48:18.246  23544-23544/com.adjans.huskerr.acharttest W/dalvikvm﹕ VFY: unable to resolve virtual method 388: Landroid/content/res/TypedArray;.getType (I)I
02-24 11:48:18.246  23544-23544/com.adjans.huskerr.acharttest D/dalvikvm﹕ VFY: replacing opcode 0x6e at 0x0002
02-24 11:48:18.276  23544-23544/com.adjans.huskerr.acharttest D/AndroidRuntime﹕ Shutting down VM
02-24 11:48:18.276  23544-23544/com.adjans.huskerr.acharttest W/dalvikvm﹕ threadid=1: thread exiting with uncaught exception (group=0x418f5c08)
02-24 11:48:18.286  23544-23544/com.adjans.huskerr.acharttest E/AndroidRuntime﹕ FATAL EXCEPTION: main
    Process: com.adjans.huskerr.acharttest, PID: 23544
    java.lang.RuntimeException: Unable to start activity ComponentInfo{com.adjans.huskerr.acharttest/com.adjans.huskerr.acharttest.MainActivity}: android.view.InflateException: Binary XML file line #7: Error inflating class com.adjans.huskerr.acharttest.DwarView
            at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2436)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2495)
            at android.app.ActivityThread.access$900(ActivityThread.java:170)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1304)
            at android.os.Handler.dispatchMessage(Handler.java:102)
            at android.os.Looper.loop(Looper.java:146)
            at android.app.ActivityThread.main(ActivityThread.java:5635)
            at java.lang.reflect.Method.invokeNative(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:515)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1291)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1107)
            at dalvik.system.NativeStart.main(Native Method)
     Caused by: android.view.InflateException: Binary XML file line #7: Error inflating class com.adjans.huskerr.acharttest.DwarView
            at android.view.LayoutInflater.createView(LayoutInflater.java:609)
            at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:702)
            at android.view.LayoutInflater.rInflate(LayoutInflater.java:761)
            at android.view.LayoutInflater.inflate(LayoutInflater.java:498)
            at android.view.LayoutInflater.inflate(LayoutInflater.java:398)
            at android.view.LayoutInflater.inflate(LayoutInflater.java:354)
            at android.support.v7.app.ActionBarActivityDelegateBase.setContentView(ActionBarActivityDelegateBase.java:228)
            at android.support.v7.app.ActionBarActivity.setContentView(ActionBarActivity.java:102)
            at com.adjans.huskerr.acharttest.MainActivity.onCreate(MainActivity.java:20)
            at android.app.Activity.performCreate(Activity.java:5585)
            at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1093)
            at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2400)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2495)
            at android.app.ActivityThread.access$900(ActivityThread.java:170)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1304)
            at android.os.Handler.dispatchMessage(Handler.java:102)
            at android.os.Looper.loop(Looper.java:146)
            at android.app.ActivityThread.main(ActivityThread.java:5635)
            at java.lang.reflect.Method.invokeNative(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:515)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1291)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1107)
            at dalvik.system.NativeStart.main(Native Method)
     Caused by: java.lang.NoSuchMethodException: <init> [class android.content.Context, interface android.util.AttributeSet]
            at java.lang.Class.getConstructorOrMethod(Class.java:472)
            at java.lang.Class.getConstructor(Class.java:446)
            at android.view.LayoutInflater.createView(LayoutInflater.java:574)
            at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:702)
            at android.view.LayoutInflater.rInflate(LayoutInflater.java:761)
            at android.view.LayoutInflater.inflate(LayoutInflater.java:498)
            at android.view.LayoutInflater.inflate(LayoutInflater.java:398)
            at android.view.LayoutInflater.inflate(LayoutInflater.java:354)
            at android.support.v7.app.ActionBarActivityDelegateBase.setContentView(ActionBarActivityDelegateBase.java:228)
            at android.support.v7.app.ActionBarActivity.setContentView(ActionBarActivity.java:102)
            at com.adjans.huskerr.acharttest.MainActivity.onCreate(MainActivity.java:20)
            at android.app.Activity.performCreate(Activity.java:5585)
            at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1093)
            at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2400)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2495)
            at android.app.ActivityThread.access$900(ActivityThread.java:170)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1304)
            at android.os.Handler.dispatchMessage(Handler.java:102)
            at android.os.Looper.loop(Looper.java:146)
            at android.app.ActivityThread.main(ActivityThread.java:5635)
            at java.lang.reflect.Method.invokeNative(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:515)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1291)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1107)
            at dalvik.system.NativeStart.main(Native Method)

Answer 1

关注this guide 。你还没有实现构造函数。为了能够在 xml 中使用 View ，您应该从 View 实现另外 2 个构造函数:

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

public DwarView(Context context, AttributeSet attrs, int defStyle) {
    super(context, attrs, defStyle);
}

将此构造函数添加到您的 customView 类中。

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