androidexercise1compass

书上的一个例子，一步一步按照树上的做但是还是出现了一点小错误：在catlog中：error openging trace file:No such file or directory(2) 指的是我自定义的view类,并且有inflate错误

03-12 02:09:57.254: D/AndroidRuntime(789): Shutting down VM
03-12 02:09:57.254: W/dalvikvm(789): threadid=1: thread exiting with uncaught exception (group=0x40a71930)
03-12 02:09:57.304: E/AndroidRuntime(789): FATAL EXCEPTION: main
03-12 02:09:57.304: E/AndroidRuntime(789): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.compassapp/com.example.compassapp.MainActivity}: android.view.InflateException: Binary XML file line #12: Error inflating class com.example.compassapp.CompassView
03-12 02:09:57.304: E/AndroidRuntime(789):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2180)
03-12 02:09:57.304: E/AndroidRuntime(789):  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2230)
03-12 02:09:57.304: E/AndroidRuntime(789):  at android.app.ActivityThread.access$600(ActivityThread.java:141)
03-12 02:09:57.304: E/AndroidRuntime(789):  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1234)
03-12 02:09:57.304: E/AndroidRuntime(789):  at android.os.Handler.dispatchMessage(Handler.java:99)
03-12 02:09:57.304: E/AndroidRuntime(789):  at android.os.Looper.loop(Looper.java:137)
03-12 02:09:57.304: E/AndroidRuntime(789):  at android.app.ActivityThread.main(ActivityThread.java:5041)
03-12 02:09:57.304: E/AndroidRuntime(789):  at java.lang.reflect.Method.invokeNative(Native Method)
03-12 02:09:57.304: E/AndroidRuntime(789):  at java.lang.reflect.Method.invoke(Method.java:511)
03-12 02:09:57.304: E/AndroidRuntime(789):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
03-12 02:09:57.304: E/AndroidRuntime(789):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
03-12 02:09:57.304: E/AndroidRuntime(789):  at dalvik.system.NativeStart.main(Native Method)
03-12 02:09:57.304: E/AndroidRuntime(789): Caused by: android.view.InflateException: Binary XML file line #12: Error inflating class com.example.compassapp.CompassView
03-12 02:09:57.304: E/AndroidRuntime(789):  at android.view.LayoutInflater.createView(LayoutInflater.java:596)
03-12 02:09:57.304: E/AndroidRuntime(789):  at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:687)
03-12 02:09:57.304: E/AndroidRuntime(789):  at android.view.LayoutInflater.rInflate(LayoutInflater.java:746)
03-12 02:09:57.304: E/AndroidRuntime(789):  at android.view.LayoutInflater.inflate(LayoutInflater.java:489)
03-12 02:09:57.304: E/AndroidRuntime(789):  at android.view.LayoutInflater.inflate(LayoutInflater.java:396)
03-12 02:09:57.304: E/AndroidRuntime(789):  at android.view.LayoutInflater.inflate(LayoutInflater.java:352)
03-12 02:09:57.304: E/AndroidRuntime(789):  at com.android.internal.policy.impl.PhoneWindow.setContentView(PhoneWindow.java:270)
03-12 02:09:57.304: E/AndroidRuntime(789):  at android.app.Activity.setContentView(Activity.java:1881)
03-12 02:09:57.304: E/AndroidRuntime(789):  at com.example.compassapp.MainActivity.onCreate(MainActivity.java:12)
03-12 02:09:57.304: E/AndroidRuntime(789):  at android.app.Activity.performCreate(Activity.java:5104)
03-12 02:09:57.304: E/AndroidRuntime(789):  at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1080)
03-12 02:09:57.304: E/AndroidRuntime(789):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2144)
03-12 02:09:57.304: E/AndroidRuntime(789):  ... 11 more
03-12 02:09:57.304: E/AndroidRuntime(789): Caused by: java.lang.NoSuchMethodException: <init> [class android.content.Context, interface android.util.AttributeSet]
03-12 02:09:57.304: E/AndroidRuntime(789):  at java.lang.Class.getConstructorOrMethod(Class.java:460)
03-12 02:09:57.304: E/AndroidRuntime(789):  at java.lang.Class.getConstructor(Class.java:431)
03-12 02:09:57.304: E/AndroidRuntime(789):  at android.view.LayoutInflater.createView(LayoutInflater.java:561)
03-12 02:09:57.304: E/AndroidRuntime(789):  ... 22 more
03-12 02:10:21.435: E/Trace(810): error opening trace file: No such file or directory (2)
03-12 02:10:22.214: D/AndroidRuntime(810): Shutting down VM
03-12 02:10:22.214: W/dalvikvm(810): threadid=1: thread exiting with uncaught exception (group=0x40a71930)
03-12 02:10:22.234: E/AndroidRuntime(810): FATAL EXCEPTION: main
03-12 02:10:22.234: E/AndroidRuntime(810): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.compassapp/com.example.compassapp.MainActivity}: android.view.InflateException: Binary XML file line #12: Error inflating class com.example.compassapp.CompassView
03-12 02:10:22.234: E/AndroidRuntime(810):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2180)
03-12 02:10:22.234: E/AndroidRuntime(810):  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2230)
03-12 02:10:22.234: E/AndroidRuntime(810):  at android.app.ActivityThread.access$600(ActivityThread.java:141)
03-12 02:10:22.234: E/AndroidRuntime(810):  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1234)
03-12 02:10:22.234: E/AndroidRuntime(810):  at android.os.Handler.dispatchMessage(Handler.java:99)
03-12 02:10:22.234: E/AndroidRuntime(810):  at android.os.Looper.loop(Looper.java:137)
03-12 02:10:22.234: E/AndroidRuntime(810):  at android.app.ActivityThread.main(ActivityThread.java:5041)
03-12 02:10:22.234: E/AndroidRuntime(810):  at java.lang.reflect.Method.invokeNative(Native Method)
03-12 02:10:22.234: E/AndroidRuntime(810):  at java.lang.reflect.Method.invoke(Method.java:511)
03-12 02:10:22.234: E/AndroidRuntime(810):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
03-12 02:10:22.234: E/AndroidRuntime(810):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
03-12 02:10:22.234: E/AndroidRuntime(810):  at dalvik.system.NativeStart.main(Native Method)
03-12 02:10:22.234: E/AndroidRuntime(810): Caused by: android.view.InflateException: Binary XML file line #12: Error inflating class com.example.compassapp.CompassView
03-12 02:10:22.234: E/AndroidRuntime(810):  at android.view.LayoutInflater.createView(LayoutInflater.java:596)
03-12 02:10:22.234: E/AndroidRuntime(810):  at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:687)
03-12 02:10:22.234: E/AndroidRuntime(810):  at android.view.LayoutInflater.rInflate(LayoutInflater.java:746)
03-12 02:10:22.234: E/AndroidRuntime(810):  at android.view.LayoutInflater.inflate(LayoutInflater.java:489)
03-12 02:10:22.234: E/AndroidRuntime(810):  at android.view.LayoutInflater.inflate(LayoutInflater.java:396)
03-12 02:10:22.234: E/AndroidRuntime(810):  at android.view.LayoutInflater.inflate(LayoutInflater.java:352)
03-12 02:10:22.234: E/AndroidRuntime(810):  at com.android.internal.policy.impl.PhoneWindow.setContentView(PhoneWindow.java:270)
03-12 02:10:22.234: E/AndroidRuntime(810):  at android.app.Activity.setContentView(Activity.java:1881)
03-12 02:10:22.234: E/AndroidRuntime(810):  at com.example.compassapp.MainActivity.onCreate(MainActivity.java:12)
03-12 02:10:22.234: E/AndroidRuntime(810):  at android.app.Activity.performCreate(Activity.java:5104)
03-12 02:10:22.234: E/AndroidRuntime(810):  at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1080)
03-12 02:10:22.234: E/AndroidRuntime(810):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2144)
03-12 02:10:22.234: E/AndroidRuntime(810):  ... 11 more
03-12 02:10:22.234: E/AndroidRuntime(810): Caused by: java.lang.NoSuchMethodException: <init> [class android.content.Context, interface android.util.AttributeSet]
03-12 02:10:22.234: E/AndroidRuntime(810):  at java.lang.Class.getConstructorOrMethod(Class.java:460)
03-12 02:10:22.234: E/AndroidRuntime(810):  at java.lang.Class.getConstructor(Class.java:431)
03-12 02:10:22.234: E/AndroidRuntime(810):  at android.view.LayoutInflater.createView(LayoutInflater.java:561)
03-12 02:10:22.234: E/AndroidRuntime(810):  ... 22 more

现贴出代码：

1。MainActivity

package com.example.compassapp;

import android.os.Bundle;
import android.app.Activity;
import android.view.Menu;

public class MainActivity extends Activity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        CompassView cv = (CompassView)findViewById(R.id.compassView);
    }

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

}

刚贴完这个发现怪不得初始化有问题。。。cv.setBearing(45)没写。。
2.compassView

package com.example.compassapp;

import android.os.Bundle;
import android.app.Activity;
import android.content.Context;
import android.content.res.Resources;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.util.AttributeSet;
import android.view.Menu;
import android.view.View;

public class CompassView extends View {
    private float bearing;
    private Paint makerPaint;
    private Paint textPaint;
    private Paint circlePaint;
    private String northString;
    private String eastString;
    private String southString;
    private String westString;
    private int textHeight;
    
    public void setBearing(float _bearing){
        bearing = _bearing;
    }
    
    public float getBearing(){
        return bearing;
    }
    public CompassView(Context context){
        super(context);
        initCompassView();
    }
    public CompassView(Context context, AttributeSet ats, int defaultStyle){
        super(context, ats, defaultStyle);
        initCompassView();
    }
    protected void initCompassView(){
        setFocusable(true);
        
        circlePaint = new Paint(Paint.ANTI_ALIAS_FLAG);
        Resources r = this.getResources();
        circlePaint.setColor(r.getColor(R.color.background_color));
        circlePaint.setStrokeWidth(1);
        circlePaint.setStyle(Paint.Style.FILL_AND_STROKE);
        northString = r.getString(R.string.cardinal_north);
        eastString = r.getString(R.string.cardinal_east);
        southString = r.getString(R.string.cardinal_south);
        westString = r.getString(R.string.cardinal_west);
        
        textPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
        textPaint.setColor(r.getColor(R.color.text_color));
        textHeight = (int)textPaint.measureText("yY");
        
        makerPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
        makerPaint.setColor(r.getColor(R.color.marker_color));
        
    }

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec){
        int measureWidth = measure(widthMeasureSpec);
        int measureHeight = measure(heightMeasureSpec);
        int d = Math.min(measureWidth, measureHeight);
        setMeasuredDimension(d,d);
    }
    
    private int measure(int measureSpec){
        int result = 0;
        int specMode = MeasureSpec.getMode(measureSpec);
        int specSize = MeasureSpec.getSize(measureSpec);
        
        if (specMode == MeasureSpec.UNSPECIFIED){
            result = 200;
        } else{
            result = specSize;
        }
        return result;
    }
    
    @Override
    protected void onDraw(Canvas canvas){
        int px = getMeasuredWidth()/2;
        int py = getMeasuredHeight()/2;
        int radius = Math.min(px, py);
        canvas.drawCircle(px, py, radius, circlePaint);
        canvas.save();
        canvas.rotate(-bearing,px,py);
        
        int textWidth = (int)textPaint.measureText("W");
        int cardinalX = px - textWidth/2;
        int cardinalY = py - radius + textHeight;
        
        for(int i=0; i<24; i++){
            canvas.drawLine(px, py-radius, px, py-radius+10, makerPaint);
            canvas.save();
            canvas.translate(0, textHeight);
            
            if (i%6 ==0){
                String dirString = "";
                switch (i) {
                case (0) :{
                    dirString = northString;
                    int arrowY = 2*textHeight;
                    canvas.drawLine(px, arrowY, px-5, 3*textHeight, makerPaint);
                    break;
                }
                case (6): dirString = eastString; break;
                case (12): dirString = southString; break;
                case (18): dirString = westString;break;
                }
                canvas.drawText(dirString, cardinalX, cardinalY, textPaint);
            }
            
            else if (i % 3 == 0){
                String angle = String.valueOf(i*15);
                float angleTextWidth = textPaint.measureText(angle);
                
                int angleTextX = (int)(px - angleTextWidth/2);
                int angleTextY = py - radius + textHeight;
                canvas.drawText(angle, angleTextX, angleTextY, textPaint);
            }
            canvas.restore();
            canvas.rotate(15,px,py);
        }
        canvas.restore();
    }
    
    

}

3.manifest

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.compassapp"
    android:versionCode="1"
    android:versionName="1.0" >

    <uses-sdk
        android:minSdkVersion="8"
        android:targetSdkVersion="17" />

    <application
        android:allowBackup="true"
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" >
        <activity
            android:name="com.example.compassapp.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>

4.main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent">

    
    <com.example.compassapp.CompassView
     xmlns:android = "http://schemas.android.com/apk/res/android"
        android:id="@+id/compassView"
        android:layout_width="fill_parent"
        android:layout_height = "fill_parent"
        />
   

</LinearLayout>

 最后将activity这样改，就好了。。。即使我使用下一行cv初始化将7,8行顺序呼唤都会出错nullpointerexception 为什么？？

@Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        CompassView cv = new CompassView(this);
//        CompassView cv = (CompassView)findViewById(R.id.compassView);
        
        setContentView(cv);
        cv.setBearing(45);

 虽然work了但是还是不甘。仔细看了catlog NoSuchMethodException:<init>[class android.Content.Context, interface android.util.AttribureSet]

所以是少了以context 和 attributeSet为参数的构造函数，加上

public CompassView(Context context, AttributeSet ats){
        super(context, ats);
        initCompassView();
    }

但是为什么不认我之前写的那两个构造函数呢？http://blog.csdn.net/z103594643/article/details/6755017