Question

我创建了一个自定义按钮。但是当我尝试使用它时，我在布局的图形视图中得到了这些异常：

java.lang.NullPointerException
at com.aspa.warehousing.CirculeButton.setText(CirculeButton.java:36)
at com.aspa.warehousing.CirculeButton.<init>(CirculeButton.java:32)
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(    at sun.reflect.NativeConstructorAccessorImpl.newInstance(    at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(    at java.lang.reflect.Constructor.newInstance(    at com.android.ide.eclipse.adt.internal.editors.layout.ProjectCallback.instantiateClass(ProjectCallback.java:437)
at com.android.ide.eclipse.adt.internal.editors.layout.ProjectCallback.loadView(ProjectCallback.java:189)
at android.view.BridgeInflater.loadCustomView(BridgeInflater.java:207)
at android.view.BridgeInflater.createViewFromTag(BridgeInflater.java:135)
at android.view.LayoutInflater.rInflate_Original(LayoutInflater.java:755)
at android.view.LayoutInflater_Delegate.rInflate(LayoutInflater_Delegate.java:64)
at android.view.LayoutInflater.rInflate(LayoutInflater.java:727)
at android.view.LayoutInflater.inflate(LayoutInflater.java:492)
at android.view.LayoutInflater.inflate(LayoutInflater.java:373)

这是我的按钮布局：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical"
    android:id="@+id/LinearLayout">
    <com.aspa.warehousing.SquareLinearLayout
        android:layout_height="match_parent"
        android:layout_width="match_parent"
        android:background="@drawable/round_button_unselect">
        <ImageView 
            android:id="@+id/button_image"
            android:layout_width="fill_parent"
            android:layout_height="fill_parent"
            android:scaleType="centerInside"/>
    </com.aspa.warehousing.SquareLinearLayout>
    <TextView 
        android:layout_marginTop="5dp"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:gravity="center_horizontal"
        android:id="@+id/button_caption"/>
</LinearLayout>

这是按钮类：

package com.aspa.warehousing;

import android.content.Context;
import android.content.res.TypedArray;
import android.graphics.drawable.Drawable;
import android.util.AttributeSet;
import android.view.LayoutInflater;
import android.widget.ImageView;
import android.widget.LinearLayout;
import android.widget.TextView;

public class CirculeButton extends LinearLayout {
    ImageView buttonImg;
    TextView buttonCaption;
    public CirculeButton(Context context) {
        super(context);
    }
    public CirculeButton(Context context, AttributeSet attrs) {
        super(context,attrs);
        LayoutInflater inflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        inflater.inflate(R.layout.circle_button, this, true);
        buttonImg = (ImageView) findViewById(R.id.button_image);
        buttonCaption = (TextView) findViewById(R.id.button_caption);

        TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.CirculeButton);

        String caption = a.getString(R.styleable.CirculeButton_buttonText);
        Drawable image = a.getDrawable(R.styleable.CirculeButton_buttonImg);

        a.recycle();

        setText(caption);
        setImage(image);
    }
    public void setText(String caption) {
        buttonCaption.setText(caption);
    }
    private void setImage(Drawable image) {
        buttonImg.setImageDrawable(image);
    }
}

setText和setImage方法引发的扩展。似乎buttonImg和buttonCaption是null，但我无法修复它！有什么建议吗？

已编辑：这就是我使用它的方式：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res/com.aspa.warehousing"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:gravity="center"
android:orientation="vertical" >

<com.aspa.warehousing.CirculeButton
    android:id="@+id/CirculeButton1"
    android:layout_width="60dp"
    android:layout_height="60dp"
    app:buttonImg="@drawable/raw_materials"
    app:buttonText="@string/raw_materials" />

</LinearLayout>

此处抛出的异常。

Answer 1

这只是一个日食错误：|

关闭日食并再次打开它：D

太容易了！

Android - 制作自定义视图组件时出错

1 个答案: