我正在尝试创建一个带有两个文本字段的自定义按钮。当我从代码创建一个实例时,它可以工作。当我尝试从 XML 膨胀时,它崩溃了。
到目前为止,我为尝试解决此问题所做的工作:
- 关注并理解了 SDK 中的 LabelView 代码示例。
- 关注并理解了这个出色的 Devoxx 自定义FlowLayout演示文稿。
- 遵循并理解了许多关于该主题的教程。
- 花了几个小时在 stackoverflow 上查看类似的问题。
- 将代码剥离回简单地将属性集传递给超类的基础。
从我读过的问题来看,最常见的原因是没有定义需要属性集的构造函数,即
MyClass(Context context, AttributeSet attrs) {
super(context, attrs);
}
在 LogCat 错误列表的末尾附近,我有:
Caused by: java.lang.NoSuchMethodException: <init> [class android.content.Context, interface android.util.AttributeSet]
这可能会导致我犯了和其他许多人一样的错误的结论,但是当您查看下面的代码时,您会发现我已经定义了此表单的构造函数。
我似乎完全按照所有消息来源所说的那样做。我只是看不到我错过了什么。
src/com.soundconception.custombuttontest2/TitledValueButton.java
package com.soundconception.custombuttontest2;
import android.content.Context;
import android.util.AttributeSet;
import android.widget.Button;
public class TitledValueButton extends Button {
public TitledValueButton(Context context) {
super(context);
}
protected TitledValueButton(Context context, AttributeSet attrs) {
super(context, attrs);
}
}
资源/值/attrs.xml
<?xml version="1.0" encoding="utf-8"?>
<resources>
<declare-styleable name="TitledValueButton">
<attr name="titleText" format="string" />
</declare-styleable>
</resources>
资源/布局/activity_main.xml
<RelativeLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res/com.soundconception.custombuttontest2"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context=".MainActivity" >
<com.soundconception.custombuttontest2.TitledValueButton
android:id="@+id/test_button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="1..2..3.."
app:titleText="Testing" />
</RelativeLayout>
src/com.soundconception.custombuttontest2/MainActivity.java
package com.soundconception.custombuttontest2;
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.activity_main);
}
@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;
}
}
日志猫
threadid=1: thread exiting with uncaught exception (group=0x41a5a700)
FATAL EXCEPTION: main
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.soundconception.custombuttontest2/com.soundconception.custombuttontest2.MainActivity}: android.view.InflateException: Binary XML file line #13: Error inflating class com.soundconception.custombuttontest2.TitledValueButton
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2211)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2261)
at android.app.ActivityThread.access$600(ActivityThread.java:141)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1256)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:137)
at android.app.ActivityThread.main(ActivityThread.java:5103)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:525)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:737)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
at dalvik.system.NativeStart.main(Native Method)
Caused by: android.view.InflateException: Binary XML file line #13: Error inflating class com.soundconception.custombuttontest2.TitledValueButton
at android.view.LayoutInflater.createView(LayoutInflater.java:603)
at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:696)
at android.view.LayoutInflater.rInflate(LayoutInflater.java:755)
at android.view.LayoutInflater.inflate(LayoutInflater.java:492)
at android.view.LayoutInflater.inflate(LayoutInflater.java:397)
at android.view.LayoutInflater.inflate(LayoutInflater.java:353)
at com.android.internal.policy.impl.PhoneWindow.setContentView(PhoneWindow.java:267)
at android.app.Activity.setContentView(Activity.java:1895)
at com.soundconception.custombuttontest2.MainActivity.onCreate(MainActivity.java:12)
at android.app.Activity.performCreate(Activity.java:5133)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2175)
... 11 more
Caused by: java.lang.NoSuchMethodException: <init> [class android.content.Context, interface android.util.AttributeSet]
at java.lang.Class.getConstructorOrMethod(Class.java:423)
at java.lang.Class.getConstructor(Class.java:397)
at android.view.LayoutInflater.createView(LayoutInflater.java:568)
... 22 more