Android:ArrayAdapter 未应用于 ListView

Question

当我在布局中将 ArrayAdapter 设置为 ListView 时遇到问题。一切看起来都很好，我没有任何错误，但是当我加载XML文件时，我在列表视图中看到的只是item1，item2等。有什么我没有添加的吗？

这是我下面的代码：

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.ListView;
public class LaunchActivity extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_launch);
    ListView lv = (ListView) findViewById(R.id.subjectListView);
    String[] subjectArray = new String[]{"Physics","Chemistry","Economics", "Geography"};
    ArrayAdapter<String> adapter = new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1, subjectArray);
    lv.setAdapter(adapter);
    lv.setOnItemClickListener(
            new AdapterView.OnItemClickListener() {
                @Override
                public void onItemClick(AdapterView<?> parent, View view, int position, long id) {

                    if (position == 0) {
                        Intent intent = new Intent(LaunchActivity.this, PhysicsFragment.class);
                        startActivity(intent);
                    } else if (position == 1) {
                        Intent intent = new Intent(LaunchActivity.this, ChemFragment.class);
                        startActivity(intent);
                    } else if (position == 2) {
                        Intent intent = new Intent(LaunchActivity.this, EconFragment.class);
                        startActivity(intent);
                    } else if (position == 3) {
                        Intent intent = new Intent(LaunchActivity.this, GeoActivity.class);
                        startActivity(intent);
                    }
                }
            }

    );
}

}

这是我的XML文件：

<ListView
    android:layout_width="wrap_content"
    android:layout_height="fill_parent"
    android:id="@+id/subjectListView"
    android:layout_alignParentLeft="true"
    android:layout_alignParentStart="true"
    android:layout_alignParentRight="true"
    android:layout_alignParentEnd="true"/>

Answer 1

如果你的意思是你在Android Studio的XML渲染器中看到item1等，那是正常的。编译您的项目并在设备上运行它，所有这些都必须正常工作。