我的ListView在android模拟器中不可见，我使用了线性布局

Question

我的问题是列表视图在我的Android模拟器上不可见 下面是我的xml文件

<?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-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MyListview">


<ListView
    android:id="@+id/listview"
    android:layout_width="368dp"
    android:layout_height="495dp"
    tools:layout_editor_absoluteX="8dp"
    tools:layout_editor_absoluteY="8dp"
    tools:ignore="MissingConstraints" />
</LinearLayout>

下面是我的string.xml文件

<resources>
<string name="app_name">MyListView</string>
<string-array name="myarray">
    <item value="Abc"></item>
    <item value="Def"></item>
    <item value="ghi"></item>
    <item value="jkl"></item>

</string-array>

下面是my.java文件：

package com.example.mypc.mylistview;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import  android.widget.*;

public class MyListview extends AppCompatActivity {
ListView lv;
ArrayAdapter ad;
String []arr={"abc","def","ghi","jkl"};
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_my_listview);

    lv=(ListView) findViewById(R.id.listview);

       ad=new ArrayAdapter<String>(getApplicationContext(),android.R.layout.simple_list_item_1,arr);

    lv.setAdapter(ad);
    lv.setOnItemClickListener(new AdapterView.OnItemClickListener() {
        @Override
        public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
          String []arr=getResources().getStringArray(R.array.myarray);
            String value=arr[position];
            Toast.makeText(getApplicationContext(),value,Toast.LENGTH_LONG).show();

        }
    });

}
}

下面是我的输出：

这是在数组适配器内部传递数组之后的输出

我的java文件中是否存在任何错误或布局错误？ 预先感谢

Answer 1

如您在屏幕截图中所见，一切都很好。列表视图在那里，但是 android.R.layout.simple_list_item_1 的颜色是白色，这就是为什么它不显示的原因。您可以尝试

例如mytextview.xml

<?xml version="1.0" encoding="utf-8"?>
<TextView xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/tv"
    android:textColor="@color/font_content"
    android:padding="5sp"
    android:layout_width="fill_parent"
    android:background="@drawable/rectgrad"
    android:singleLine="true"
    android:gravity="center"
    android:layout_height="fill_parent"/>

您的Java文件现在为：

package com.example.mypc.mylistview;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import  android.widget.*;

public class MyListview extends AppCompatActivity {
ListView lv;
ArrayAdapter ad;
String []arr={"abc","def","ghi","jkl"};
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_my_listview);

    lv=(ListView) findViewById(R.id.listview);

       ad=new ArrayAdapter<String>(getApplicationContext(),R.layout.mytextview,arr);

    lv.setAdapter(ad);
    lv.setOnItemClickListener(new AdapterView.OnItemClickListener() {
        @Override
        public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
          String []arr=getResources().getStringArray(R.array.myarray);
            String value=arr[position];
            Toast.makeText(getApplicationContext(),value,Toast.LENGTH_LONG).show();

        }
    });

}
}

它绝对有效。

Answer 2

Simple use this in MainActivity.java


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        ListView  listView=findViewById(R.id.listviewa);

        String [] value=getResources().getStringArray(R.array.radio_buttons);
         ArrayAdapter<String> adapter = new ArrayAdapter<String>(this,
                android.R.layout.simple_list_item_1, android.R.id.text1, value);
        listView.setAdapter(adapter);


    }

//---------------------String.xml-

<resources>
    <string name="app_name">YourAppName</string>


    <string-array name="radio_buttons">
        <item>ABC</item>
        <item>DEF</item>
        <item>GHX</item>
        <item>IJK</item>
    </string-array>
</resources>