[移动开发] 学习安卓开发第七天【网格视图qq相册页面】【下拉；列表框】【下拉列表框实例】【列表视图】

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[移动开发]学习安卓开发第七天【网格视图qq相册页面】【下拉；列表框】【下拉列表框实例】【列表视图】

<?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"
    android:orientation="vertical"
    tools:context=".MainActivity">

    <ImageView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:src="@mipmap/ic_launcher"
        />

    <TextView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="2021年3月29日"
        android:paddingTop="10dp"
        android:paddingBottom="10dp"
        />
    <GridView
        android:id="@+id/gridView"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:numColumns="auto_fit"
        android:gravity="center"
        android:verticalSpacing="5dp"
        android:columnWidth="100dp"

        />

</LinearLayout>

package com.example.qqablum;

import androidx.appcompat.app.AppCompatActivity;

import android.content.Context;
import android.media.Image;
import android.os.Bundle;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.GridView;
import android.widget.ImageView;

public class MainActivity extends AppCompatActivity {
private int [] picture=new int[]{
  R.drawable.aa,R.drawable.bb,R.drawable.cc,R.drawable.dd
        ,R.drawable.ee,R.drawable.ff


};
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        GridView gridView=findViewById(R.id.gridView);
        gridView.setAdapter(new ImageAdpater(this));

    }

    public class ImageAdpater extends BaseAdapter{
        private Context mContext;
        public ImageAdpater(Context c){
            mContext=c;
        }

        @Override
        public int getCount() {
            return picture.length;
        }

        @Override
        public Object getItem(int i) {
            return null;
        }

        @Override
        public long getItemId(int i) {
            return 0;
        }

        @Override
        public View getView(int position, View converView, ViewGroup parent) {
            ImageView imageView;
            if(converView==null){
                imageView=new ImageView(mContext);
                imageView.setScaleType(ImageView.ScaleType.CENTER_CROP);
            }else{
                imageView=(ImageView) converView;
            }
            imageView.setImageResource(picture[position]);



            return imageView;
        }
    }

}

?老感觉我写错了，效果图不太一样

下拉列表框：方法一：

<?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">

    <Spinner
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:entries="@array/ctype"
        />
</androidx.constraintlayout.widget.ConstraintLayout>

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <string-array name="ctype">
        <item>全部</item>
        <item>电影</item>
        <item>图书</item>
        <item>游戏</item>

    </string-array>


</resources>

在value创建一个arrays.xml的文件

下拉列表：方法二：

package com.example.cc;

import androidx.appcompat.app.AppCompatActivity;

import android.os.Bundle;
import android.widget.ArrayAdapter;
import android.widget.Spinner;
import android.widget.Toast;

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        String []ctype=new String[]{
                "全部","美术","音乐","体育"
        };
        ArrayAdapter<String> adapter=new ArrayAdapter<String>(this,android.R.layout.simple_spinner_item,ctype);

        adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
        Spinner spinner=findViewById(R.id.spinner);
        spinner.setAdapter(adapter);
String str=spinner.getSelectedItem().toString();
        Toast.makeText(MainActivity.this, str, Toast.LENGTH_SHORT).show();

    }
}

<?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">

    <Spinner
        android:id="@+id/spinner"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"

        />
</androidx.constraintlayout.widget.ConstraintLayout>

package com.example.cc;

import androidx.appcompat.app.AppCompatActivity;

import android.os.Bundle;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.Spinner;
import android.widget.Toast;

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Spinner spinner=findViewById(R.id.spinner);
        spinner.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
            @Override
            public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
                String result=parent.getItemAtPosition(position).toString();
                Toast.makeText(MainActivity.this, result, Toast.LENGTH_SHORT).show();
            

            }

            @Override
            public void onNothingSelected(AdapterView<?> adapterView) {

            }
        });
    }
}

添加一个监听器，点击会有显示效果

<?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"
    android:orientation="horizontal"
    tools:context=".MainActivity">

    <Spinner

android:id="@+id/spinner"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:entries="@array/ctype"
        />
<EditText
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="搜素"

    android:textColor="#1010D5"/>

</LinearLayout>

列表视图：方法一：

<?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=".MainActivity">

    <ListView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:entries="@array/ctype"
        />

</RelativeLayout>

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <string-array name="ctype">
        <item>
            全部
        </item>
        <item>电影</item>
        <item>图书</item>
        <item>游戏</item>


    </string-array>




</resources>

?方法二：

package com.example.nnn;

import androidx.appcompat.app.AppCompatActivity;

import android.os.Bundle;
import android.widget.Adapter;
import android.widget.ArrayAdapter;
import android.widget.ListView;

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        String[]ctype=new String[]{
                "全部","游戏","图书","电视"
        };
        ArrayAdapter<String>adapter=new ArrayAdapter<String>(this,android.R.layout.simple_list_item_1,ctype);
        ListView listView=findViewById(R.id.listView);
        listView.setAdapter(adapter);

    }
}

实现效果一样