Android Spinner和GridView组件的使用示例

一. 概述：

spinner是我们所熟悉的下拉框列表。与listview类似，我们必须为spinner对象指定一个adapter。我们从spinner的简单用法开始讲述。

二. 实现

mainactivity.java

package com.example.demo03_29;
 
import androidx.appcompat.app.appcompatactivity;
 
import android.os.bundle;
import android.view.view;
import android.widget.adapter;
import android.widget.adapterview;
import android.widget.arrayadapter;
import android.widget.spinner;
import android.widget.textview;
 
public class mainactivity extends appcompatactivity implements adapterview.onitemselectedlistener {
    textview choice;
    arrayadapter<charsequence> adapter;
    @override
    protected void oncreate(bundle savedinstancestate) {
        super.oncreate(savedinstancestate);
        setcontentview(r.layout.activity_main);
 
        choice=(textview) this.findviewbyid(r.id.choice);
 
        spinner spinner=(spinner)this.findviewbyid(r.id.sp1);
        adapter=arrayadapter.createfromresource(this, r.array.habit,
                android.r.layout.simple_spinner_item);
        adapter.setdropdownviewresource(android.r.layout.simple_spinner_dropdown_item);
        spinner.setadapter(adapter);
        spinner.setonitemselectedlistener(this);
    }
 
 
    @override
    public void onitemselected(adapterview<?> adapterview, view view, int i, long l) {
        choice.settext(adapter.getitem(i));
    }
 
    @override
    public void onnothingselected(adapterview<?> adapterview) {
 
    }
}

在values包下的 string.xml

<resources>
    <string name="app_name">demo03-29</string>
<string-array name="habit">
    <item>10公里夜跑</item>
    <item>爬山</item>
    <item>游泳</item>
    <item>吃饭</item>
    <item>打代码</item>
</string-array>
</resources>

activity_main.xml

<?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">
 
    <linearlayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal">
        <textview
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="你喜欢的运动"/>
        <spinner
            android:id="@+id/sp1"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"/>
    </linearlayout>
 
    <view
        android:layout_width="match_parent"
        android:layout_height="30dp"
        android:background="#05adf8"/>
 
    <textview
        android:id="@+id/choice"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:gravity="center"
        />
</linearlayout>

sipnner_down.xml

<?xml version="1.0" encoding="utf-8"?>
<linearlayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="horizontal">
 
    <imageview
        android:id="@+id/p01"
        android:layout_width="64dp"
        android:layout_height="64dp"
        />
    <linearlayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="vertical">
    <textview
        android:id="@+id/t1"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"/>
    <textview
        android:id="@+id/t2"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"/>
    </linearlayout>
 
</linearlayout>

这个布局比较简单，就是在linearlayout中放置一个linearlayout、一个分隔组件用的view和一个显示所选结果的textview。在其中嵌套的linearlayout中放置一个用于提示用的textview和下拉框spinner。

三. 美化

myadapter.java

package com.example.demo03_29;
 
import android.content.context;
import android.view.layoutinflater;
import android.view.view;
import android.view.viewgroup;
import android.widget.arrayadapter;
import android.widget.imageview;
import android.widget.textview;
 
import androidx.annotation.nonnull;
 
public class myarrayapater extends arrayadapter {
    private layoutinflater minflater;
    string[] titles;
    string[] desc={
            "集成工具",
            "高速保存，随时存储",
            "优质资源，尽在迅雷",
            "集成开发工具",
            "学习神器"
    };
    int[] photos={r.drawable.p1,r.drawable.p2,r.drawable.p3,r.drawable.p4,r.drawable.p5};
 
    public myarrayapater(@nonnull context context, int resource, charsequence[] objects) {
        super(context, resource, objects);
 
        minflater=(layoutinflater) context.getsystemservice(context.layout_inflater_service);
        titles=context.getresources().getstringarray(r.array.habit);
    }
    @override
    public int getcount(){
        return titles.length;
    }
    @override
    public view getdropdownview(int position, view convertview, viewgroup parent){
        view v;
        v=minflater.inflate(r.layout.spinner_down,parent,false);
 
        imageview iv=(imageview)v.findviewbyid(r.id.p01);
        iv.setimageresource(photos[position]);
        textview tv01=(textview) v.findviewbyid(r.id.t1);
        tv01.settext(titles[position]);
        textview tv02=(textview) v.findviewbyid(r.id.t2);
        tv02.settext(desc[position]);
        return v;
    }
}

修改 mainactivity.java

四. gridview

gridview以二维表格的方式显示数据，若数据比较多，该组件将提供垂直滚动条。我们用一个列子来说明gridview的使用方法。

activity_main.xml

<?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=".mainactivity">
 
    <gridview
        android:id="@+id/gr1"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:numcolumns="4"
        />
 
</linearlayout>

imgeadapter.java

package com.example.demo0330;
 
import android.content.context;
import android.view.view;
import android.view.viewgroup;
import android.widget.baseadapter;
import android.widget.gridview;
import android.widget.imageview;
 
public class imageadapter extends baseadapter {
    private int[] images={
            r.drawable.p1, r.drawable.p2, r.drawable.p3, r.drawable.p4,
            r.drawable.p1, r.drawable.p2, r.drawable.p3, r.drawable.p4,
            r.drawable.p1, r.drawable.p2, r.drawable.p3, r.drawable.p4,
            r.drawable.p1, r.drawable.p2, r.drawable.p3, r.drawable.p4,
            r.drawable.p1, r.drawable.p2, r.drawable.p3, r.drawable.p4,
 
    };
    private context context;
    public imageadapter(context context){
        this.context=context;
    }
 
 
    @override
    public int getcount() {
        return images.length;
    }
 
    @override
    public object getitem(int position) {
        return images[position];
    }
 
    @override
    public long getitemid(int position) {
        return position;
    }
 
    @override
    public view getview(int position, view convertview, viewgroup parent) {
        imageview imageview;
        if (convertview==null){
            imageview=new imageview(context);
            int width= gridview.layoutparams.match_parent;
            int heght= gridview.layoutparams.match_parent;
            imageview.setlayoutparams(new viewgroup.layoutparams(width,heght));
            imageview.setscaletype(imageview.scaletype.center_inside);
        }else{
            imageview=(imageview) convertview;
        }
        imageview.setimageresource(images[position]);
        return imageview;
    }
}

mainactivity.java

package com.example.demo0330;
 
import androidx.appcompat.app.appcompatactivity;
 
import android.os.bundle;
import android.view.view;
import android.widget.adapterview;
import android.widget.gridview;
import android.widget.toast;
 
public class mainactivity extends appcompatactivity {
 
    @override
    protected void oncreate(bundle savedinstancestate) {
        super.oncreate(savedinstancestate);
        setcontentview(r.layout.activity_main);
 
        gridview gridview=(gridview) findviewbyid(r.id.gr1);
        gridview.setadapter(new imageadapter(this));
        gridview.setonitemclicklistener(new adapterview.onitemclicklistener() {
            @override
            public void onitemclick(adapterview<?> adapterview, view view, int position, long l) {
                toast.maketext(mainactivity.this,"现在点击的是位置在"+(position+1)+"张照片",toast.length_long).show();
            }
        });
    }
}

效果图:

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