ListView未在项目上显示文本

Question

我希望显示来自editText的文本输入，并使用ArrayAdapter将其显示在listView中，单击按钮时，listView确实会得到添加的项，但不包含文本：

以下是代码：

    <?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="match_parent"
    android:layout_height="match_parent"
    tools:context="com.example.blink.blink.MainActivity">


        <RelativeLayout
            android:layout_width="match_parent"
            android:layout_height="61dp">

            <EditText
                android:layout_width="280dp"
                android:layout_height="60dp"
                android:hint="Type a quote ..  "
                android:id="@+id/quoteField" />

            <Button
                android:layout_width="wrap_content"
                android:layout_height="60dp"
                android:text="Add Quote"
                android:id="@+id/addQuote"
                android:fontFamily="sans-serif-condensed"
                android:background="#f6546a"
                android:layout_marginLeft="10dp"
                android:layout_toRightOf="@id/quoteField" />
        </RelativeLayout>
        <ListView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:id="@+id/quotelistView"
            android:foreground="#f6546a"/>

</LinearLayout>

以及：

    public class MainActivity extends AppCompatActivity {


    Button createBtn ;
    EditText quoteField;
    ListView quotesListView;
    ArrayList<String> quotesArrayList;


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

        createBtn = (Button)  findViewById(R.id.addQuote);
        quoteField = (EditText)  findViewById(R.id.quoteField);
        quotesListView = (ListView)  findViewById(R.id.quotelistView);

        quotesArrayList = new ArrayList<>();



        createBtn.setOnClickListener(new View.OnClickListener() {
            public void onClick(View v)
            {
                quotesArrayList.add(quoteField.getText().toString());
                SetAdapter();
                quoteField.setText(" ");
            }
        });
    }


        private void SetAdapter()
        {
            ArrayAdapter<String> Adapter = new ArrayAdapter<>(MainActivity.this, android.R.layout.simple_list_item_1, quotesArrayList);
            quotesListView.setAdapter(Adapter);
        }

}

Answer 1

每次更改数组中的数据时，都不需要重置适配器。您应该做的是保持对适配器的引用，并在更改列表中的数据时调用adapter.notifyDataSetChanged()。

 public class MainActivity extends AppCompatActivity {


    Button createBtn ;
    EditText quoteField;
    ListView quotesListView;
    ArrayList<String> quotesArrayList;
    ArrayAdapter<String> adapter;


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

        createBtn = (Button)  findViewById(R.id.addQuote);
        quoteField = (EditText)  findViewById(R.id.quoteField);
        quotesListView = (ListView) findViewById(R.id.quotelistView);

        quotesArrayList = new ArrayList<>();
        adapter = new ArrayAdapter<>(MainActivity.this, android.R.layout.simple_list_item_1, quotesArrayList);
        quotesListView.setAdapter(adapter);



        createBtn.setOnClickListener(new View.OnClickListener() {
            public void onClick(View v)
            {
                quotesArrayList.add(quoteField.getText().toString());
                adapter.notifyDataSetChanged();
                quoteField.setText(" ");
            }
        });
    }

}

Answer 2

试试看！

createBtn.setOnClickListener(new View.OnClickListener() {
        public void onClick(View v)
        {
            quotesArrayList.add(quoteField.getText().toString());
            SetAdapter(quotesArrayList);

            quoteField.setText(" ");
        }
    });
}


    private void SetAdapter(ArrayList<String> quotesArrayList)
    {
        ArrayAdapter<String> Adapter = new ArrayAdapter<>(MainActivity.this, android.R.layout.simple_list_item_1, quotesArrayList);
        quotesListView.setAdapter(Adapter);
        Adapter.notifyDataSetChanged();
    }