Question

我正在做的是使用EMBEDDED LAYOUT在Google Glass中使用CardScrollView插入卡片，因为卡片制作工具中尚未提供表格布局。让我们假设每个表都有1个textView。发生的事情是当我插入1-3布局时，没有任何错误，但是当我插入第4个布局时，它在这行中给了我一个java.lang.NullPointerException。

    tv4.setText('Value for table 4');

这是我的代码：

注意：我在每个表中至少有5个TextView。在这里简单。

    protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    createCards();

    mCardScrollView = new CardScrollView(this);
    mAdapter = new ExampleCardScrollAdapter();
    mCardScrollView.setAdapter(mAdapter);
    mCardScrollView.activate();
    setContentView(mCardScrollView);


    TextView tv1 = (TextView) findViewById(R.id.textView1);
    TextView tv2 = (TextView) findViewById(R.id.textView2);
    TextView tv3 = (TextView) findViewById(R.id.textView3);
    TextView tv4 = (TextView) findViewById(R.id.textView4);



    tv1.setText('Value for table 1');
    tv2.setText('Value for table 2');
    tv3.setText('Value for table 3');
    tv4.setText('Value for table 4');
    }

private void createCards(){
    mCards = new ArrayList<CardBuilder>();

     mCards.add(new CardBuilder(this, CardBuilder.Layout.EMBED_INSIDE)
    .setEmbeddedLayout(R.layout.activity_layout1)
    .setFootnote("TABLE 1"));

     mCards.add(new CardBuilder(this, CardBuilder.Layout.EMBED_INSIDE)
    .setEmbeddedLayout(R.layout.activity_layout2)
    .setFootnote("TABLE 2"));

     mCards.add(new CardBuilder(this, CardBuilder.Layout.EMBED_INSIDE)
    .setEmbeddedLayout(R.layout.activity_layout3)
    .setFootnote("TABLE 3"));

     mCards.add(new CardBuilder(this, CardBuilder.Layout.EMBED_INSIDE)
    .setEmbeddedLayout(R.layout.activity_layout4)
    .setFootnote("TABLE 4")); 
    }

private class ExampleCardScrollAdapter extends CardScrollAdapter {

    @Override
    public int getPosition(Object item) {
        return mCards.indexOf(item);
    }

    @Override
    public int getCount() {
        return mCards.size();
    }

    @Override
    public Object getItem(int position) {
        return mCards.get(position);
    }

    @Override
    public int getViewTypeCount() {
        return CardBuilder.getViewTypeCount();
    }

    @Override
    public int getItemViewType(int position){
        return mCards.get(position).getItemViewType();
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        return mCards.get(position).getView(convertView, parent);
    }
}

activity_layout1

<?xml version="1.0" encoding="utf-8"?>
<TableLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="wrap_content"
android:layout_height="match_parent"
android:orientation="horizontal" >

<TableRow>

    <TextView
        android:padding="3dip"
        android:textSize="20sp"
        android:text="@string/textViewTitle1"
        android:textColor="@color/muted" />
    <TextView
        android:id="@+id/textView1"
        android:gravity="right"
        android:padding="3dip"
        android:textSize="20sp" />

</TableRow>
</TableLayout>

activity_layout2

<?xml version="1.0" encoding="utf-8"?>
<TableLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="wrap_content"
android:layout_height="match_parent"
android:orientation="horizontal" >

<TableRow>

    <TextView
        android:padding="3dip"
        android:textSize="20sp"
        android:text="@string/textViewTitle2"
        android:textColor="@color/muted" />
    <TextView
        android:id="@+id/textView2"
        android:gravity="right"
        android:padding="3dip"
        android:textSize="20sp" />

</TableRow>
</TableLayout>

activity_layout3

<?xml version="1.0" encoding="utf-8"?>
<TableLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="wrap_content"
android:layout_height="match_parent"
android:orientation="horizontal" >

<TableRow>

    <TextView
        android:padding="3dip"
        android:textSize="20sp"
        android:text="@string/textViewTitle4"
        android:textColor="@color/muted" />
    <TextView
        android:id="@+id/textView3"
        android:gravity="right"
        android:padding="3dip"
        android:textSize="20sp" />

</TableRow>
</TableLayout>

activity_layout4

<?xml version="1.0" encoding="utf-8"?>
<TableLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="wrap_content"
android:layout_height="match_parent"
android:orientation="horizontal" >

<TableRow>

    <TextView
        android:padding="3dip"
        android:textSize="20sp"
        android:text="@string/textViewTitle4"
        android:textColor="@color/muted" />
    <TextView
        android:id="@+id/textView4"
        android:gravity="right"
        android:padding="3dip"
        android:textSize="20sp" />

</TableRow>
</TableLayout>

适配器

    private class ExampleCardScrollAdapter extends CardScrollAdapter {

    @Override
    public int getPosition(Object item) {
        return mCards.indexOf(item);
    } 

    @Override
    public int getCount() {
        return mCards.size();
    }


    @Override
    public Object getItem(int position) {
        return mCards.get(position);
    }

    @Override
    public int getViewTypeCount() {
        return CardBuilder.getViewTypeCount();
    }

    @Override
    public int getItemViewType(int position){
        return mCards.get(position).getItemViewType();
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        return mCards.get(position).getView(convertView, parent);
    }
}

请帮忙，因为我已经在这里呆了好几天了。谢谢！

Answer 1

为各种观点设置文字的方式有一些问题。

为什么崩溃

崩溃的原因是因为CardScrollView目前一次检索5 Views，当前一个检索到两个方向的CardScrollView。由于Views从位置0开始，因此只会加载位置0,1和2的tv1：这会为tv2，tv2和{{1}设置文字它们在视图层次结构中是可能的。

由于尚未添加tv4，因此尝试检索View将返回null。

如何解决此问题

由于CardScrollView中的每张卡片都具有相同的布局，因此您无需创建4个单独的卡片并在onCreate中初始化它们。您应该在需要时膨胀Views并适当地设置文本或其他数据。

card_layout.xml：

<?xml version="1.0" encoding="utf-8"?>
<TableLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="wrap_content"
android:layout_height="match_parent"
android:orientation="horizontal" >

<TableRow>

    <TextView
        android:padding="3dip"
        android:textSize="20sp"
        android:text="@string/textViewTitle"
        android:textColor="@color/muted" />
    <TextView
        android:id="@+id/textView"
        android:gravity="right"
        android:padding="3dip"
        android:textSize="20sp" />

</TableRow>
</TableLayout>

Adapter：

private class ExampleCardScrollAdapter extends CardScrollAdapter {

    @Override
    public int getPosition(Object item) {
        return mTexts.indexOf(item);
    } 

    @Override
    public int getCount() {
        return mTexts.size();
    }


    @Override
    public Object getItem(int position) {
        return mTexts.get(position);
    }

    @Override
    public int getViewTypeCount() {
        return 1;
    }

    @Override
    public int getItemViewType(int position){
        return CardBuilder.EMBED_INSIDE.ordinal();
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        View view = new CardBuilder(this, CardBuilder.Layout.EMBED_INSIDE)
                .setEmbeddedLayout(R.layout.card_layout)
                .setFootnote("TABLE " + position)
                .getView(convertView, parent);
        TextView textView = view.findViewById(R.id.textView);

        textView.setText(mTexts.get(position));
        return view;        
    }
}

然后，在Activity：

中

protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    createTexts();

    mCardScrollView = new CardScrollView(this);
    mAdapter = new ExampleCardScrollAdapter();
    mCardScrollView.setAdapter(mAdapter);
    mCardScrollView.activate();  // This should be moved in onResume.
    setContentView(mCardScrollView);
}

private void createTexts(){
    mTexts = new ArrayList<String>();

    mTexts.add("Value for table 1");
    mTexts.add("Value for table 2");
    mTexts.add("Value for table 3");
    mTexts.add("Value for table 4");
}

使用CardScrollView的Google Glass多重嵌入式布局

1 个答案:

为什么崩溃

如何解决此问题