ListView CustomAdapter不显示第一个位置结果

Question

我是Android Studio的新手，通常来说都是编码人员，我正在尝试显示具有颜色图像和颜色名称的自定义ListView。我使用了一个自定义适配器，使用两个包含可绘制图像颜色和名称字符串的数组来为视图填充视图。

我遇到的问题-定制适配器仅显示位置1及更高位置的图层。例如，第一层应为img_01和“红色”-它显示的是img_02和“橙色”。

我已经尝试调试代码，并且看起来尽管适配器正在设置位置0的值，但我无法找到它不显示的原因（因为其他显示的很好）。

图像和名称只是占位符，因此不包含可绘制对象和名称的替代解决方案将不可行，

提前谢谢您

CustomAdapter.java

public class CustomAdapter extends BaseAdapter {

    Context context;
    int[] images;
    String[] colour;
    LayoutInflater mInflater;

    public CustomAdapter(Context c, int[] i, String[] col) {
        this.context = c; //sets the application context that has been passed to the adapter
        this.images = i; //sets the images array that has been passed to the adapter
        this.colour = col; //sets the colour array that has been passed to the adapter
        mInflater = (LayoutInflater.from(context)); //sets the layout inflater from context
    }

    @Override
    public int getCount() { //total number of elements in the array
        return images.length;
    }

    @Override
    public Object getItem(int position) { //gets the item using the position
        return null;
    }

    @Override
    public long getItemId(int position) { //gets the item position
        return position;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) { //this is used to update the view

        convertView = mInflater.inflate(R.layout.custom_layout, null);

        ImageView image = convertView.findViewById(R.id.imageView);

        TextView text = convertView.findViewById(R.id.textView);

        text.setText(colour[position]);
        image.setImageResource(images[position]);
        return convertView;

    }
}

MainActivity.java

public class MainActivity extends AppCompatActivity {

    ListView mListView;

    int[] images = {R.drawable.img01,
    R.drawable.img02,
    R.drawable.img03,
    R.drawable.img04};

    String[] colour = {"Red",
    "Orange",
    "Yellow",
    "Green"};

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        mListView = findViewById(R.id.listView);

        CustomAdapter customAdapter = new CustomAdapter(getApplicationContext(), images, colour);
        //passes information of images and application context to the item adapter
        mListView.setAdapter(customAdapter);
        //sets the adapter to the listview

    }
}

custom_layout.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent" android:layout_height="match_parent">


    <ImageView
        android:id="@+id/imageView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentStart="true"
        android:layout_alignParentLeft="true"
        android:layout_alignParentTop="true"
        android:layout_marginStart="7dp"
        android:layout_marginLeft="7dp"
        android:layout_marginTop="9dp"
        app:srcCompat="@drawable/img01" />

    <TextView
        android:id="@+id/textView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentStart="true"
        android:layout_alignParentLeft="true"
        android:layout_alignParentTop="true"
        android:layout_marginStart="99dp"
        android:layout_marginLeft="99dp"
        android:layout_marginTop="36dp"
        android:text="colourName" />

</RelativeLayout>

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <ListView
        android:id="@+id/listView"
        android:layout_width="409dp"
        android:layout_height="729dp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />
</androidx.constraintlayout.widget.ConstraintLayout>

Answer 1

创建自定义类

public class ExampleItem {
    private int mImageResource; //your color image
    private String mText1; //your text

    public ExampleItem(int imageResource, String text1) {
        mImageResource = imageResource;
        mText1 = text1;
    }
    public int getImageResource() {
        return mImageResource;
    }
    public String getText1() {
        return mText1;
    }
}

```
创建XML布局
```

<?xml version="1.0" encoding="utf-8"?>
<android.support.v7.widget.CardView xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_marginBottom="4dp"
    app:cardCornerRadius="4dp">
    <RelativeLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_margin="4dp">
        <ImageView
            android:id="@+id/imageView"
            android:layout_width="50dp"
            android:layout_height="50dp"
            android:padding="2dp" />
        <TextView
            android:id="@+id/textView"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_alignParentTop="true"
            android:layout_toEndOf="@+id/imageView"
            android:text="Line 1"
            android:textColor="@android:color/black"
            android:textSize="20sp"
            android:textStyle="bold" />
    </RelativeLayout>
</android.support.v7.widget.CardView>

```
创建回收者视图适配器
```

public class ExampleAdapter extends RecyclerView.Adapter<ExampleAdapter.ExampleViewHolder> {
    private ArrayList<ExampleItem> mExampleList;
    public static class ExampleViewHolder extends RecyclerView.ViewHolder {
        public ImageView mImageView;
        public TextView mTextView1;

        public ExampleViewHolder(View itemView) {
            super(itemView);
            mImageView = itemView.findViewById(R.id.imageView);
            mTextView1 = itemView.findViewById(R.id.textView);
        }
    }
    public ExampleAdapter(ArrayList<ExampleItem> exampleList) {
        mExampleList = exampleList;
    }
    @Override
    public ExampleViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View v = LayoutInflater.from(parent.getContext()).inflate(R.layout.example_item, parent, false);
        ExampleViewHolder evh = new ExampleViewHolder(v);
        return evh;
    }
    @Override
    public void onBindViewHolder(ExampleViewHolder holder, int position) {
        ExampleItem currentItem = mExampleList.get(position);
        holder.mImageView.setImageResource(currentItem.getImageResource());
        holder.mTextView1.setText(currentItem.getText1());
    }
    @Override
    public int getItemCount() {
        return mExampleList.size();
    }
}

```
您的activity_main.xml
```

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="com.example.application.recyclerviewproject.MainActivity">
    <android.support.v7.widget.RecyclerView
        android:id="@+id/recyclerView"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:background="@android:color/darker_gray"
        android:padding="4dp"
        android:scrollbars="vertical" />
</RelativeLayout>

```
MainActivity.java
```

public class MainActivity extends AppCompatActivity {
    private RecyclerView mRecyclerView;
    private RecyclerView.Adapter mAdapter;
    private RecyclerView.LayoutManager mLayoutManager;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        ArrayList<ExampleItem> exampleList = new ArrayList<>();
        exampleList.add(new ExampleItem(R.drawable.img01, "Red"));
        exampleList.add(new ExampleItem(R.drawable.img02, "Orange"));
        exampleList.add(new ExampleItem(R.drawable.img03, "Yellow"));
        exampleList.add(new ExampleItem(R.drawable.img04, "Green"));

        mRecyclerView = findViewById(R.id.recyclerView);
        mRecyclerView.setHasFixedSize(true);
        mLayoutManager = new LinearLayoutManager(this);
        mAdapter = new ExampleAdapter(exampleList);
        mRecyclerView.setLayoutManager(mLayoutManager);
        mRecyclerView.setAdapter(mAdapter);
    }
}

Answer 2

<ListView
    ...
    android:layout_height="wrap_content"/>

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