android之GridView&RecycleView

一、GridView

1、简介：GridView是一个在二维可滚动的网格中展示内容的控件。网格中的内容通过使用adapter2自动插入到布局中。

2、案例：手机的功能菜单界面

3、GridView的xml文件：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical" android:layout_width="match_parent"
    android:layout_height="match_parent">
    <GridView
        android:id="@+id/menu_grid"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:numColumns="3"
        android:layout_margin="20dp"
        />
</LinearLayout>

4、适配器的xml文件：

<?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="wrap_content"
    android:orientation="vertical">

    <ImageView
        android:id="@+id/menu_img"
        android:layout_width="90dp"
        android:layout_height="90dp"
        android:layout_margin="5dp"/>

    <TextView
        android:id="@+id/menu_text"
        android:layout_width="wrap_content"
        android:layout_height="60dp"
        android:textSize="24dp"
        android:layout_margin="5dp"/>

</LinearLayout>

5、GridView的逻辑代码：

package com.me.androidstudy;

import android.app.Activity;
import android.os.Bundle;
import android.widget.GridView;

import androidx.annotation.Nullable;

import com.me.adapter.MenuAdapter;
import com.me.domain.MenuItem;

import java.util.ArrayList;
import java.util.List;

public class Activity_grid extends Activity {
    GridView menu_gridView;
    MenuAdapter menuAdapter;
    List<MenuItem> data = new ArrayList<>();
    public void initView(){
        menu_gridView = findViewById(R.id.menu_grid);
        menuAdapter = new MenuAdapter();
    }
    public void action(){
        data.add(new MenuItem("二手车",R.drawable.car));
        data.add(new MenuItem("彩票",R.drawable.cp));
        data.add(new MenuItem("日历",R.drawable.data));
        data.add(new MenuItem("记事本",R.drawable.jsb));
        data.add(new MenuItem("新闻热点",R.drawable.news));
        data.add(new MenuItem("网络设置",R.drawable.wf));
        data.add(new MenuItem("天气",R.drawable.tq));
        data.add(new MenuItem("视频",R.drawable.tv));
        data.add(new MenuItem("应用市场",R.drawable.yysc));
        menuAdapter.setData(data);
        menu_gridView.setAdapter(menuAdapter);
    }
    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_grid);
        initView();
        action();
    }
}

6、适配器数据项实体：

package com.me.domain;

public class MenuItem {
    private String menuTitle;
    private int res_id;

    public MenuItem(String menuTitle, int res_id) {
        this.menuTitle = menuTitle;
        this.res_id = res_id;
    }

    public String getMenuTitle() {
        return menuTitle;
    }

    public void setMenuTitle(String menuTitle) {
        this.menuTitle = menuTitle;
    }

    public int getRes_id() {
        return res_id;
    }

    public void setRes_id(int res_id) {
        this.res_id = res_id;
    }
}

7、适配器的逻辑代码：（baseAdapter）

package com.me.adapter;

import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.ImageView;
import android.widget.TextView;

import com.me.androidstudy.R;
import com.me.domain.MenuItem;

import java.util.ArrayList;
import java.util.List;

public class MenuAdapter extends BaseAdapter {

    List<MenuItem> data = new ArrayList<>();

    public void setData(List<MenuItem> data) {
        this.data = data;
    }

    @Override
    public int getCount() {
        return data.size();
    }

    @Override
    public Object getItem(int position) {
        return data.get(position);
    }

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

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        View menuItem = LayoutInflater.from(parent.getContext()).inflate(R.layout.menu_adapter, null);
        ImageView menu_img = menuItem.findViewById(R.id.menu_img);
        TextView menu_text = menuItem.findViewById(R.id.menu_text);
        menu_img.setBackgroundResource(data.get(position).getRes_id());
        menu_text.setText(data.get(position).getMenuTitle());
        return menuItem;
    }
}

二、RecycleView

1、简介：RecyclerView是Android一个更强大的控件,其不仅可以实现和ListView同样的效果,还有优化了ListView中的各种不足。其可以实现数据纵向滚动,也可以实现横向滚动(ListView做不到横向滚动)。接下来讲解RecyclerView的用法。

2、案例：学生信息列表（图片+文字）

3、依赖：

dependencies 
{
    implementation 'androidx.recyclerview:recyclerview:1.1.0'
}

4、RecycleView的xml文件：

<?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:orientation="vertical" android:layout_width="match_parent"
    android:layout_height="match_parent">

    <androidx.recyclerview.widget.RecyclerView
        android:id="@+id/students"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        />
</androidx.constraintlayout.widget.ConstraintLayout>

5、适配器的xml文件：

<?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="wrap_content"
    android:background="#1DEBE6E6"
    android:orientation="horizontal">

    <ImageView
        android:id="@+id/sex"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_margin="5dp"/>

    <TextView
        android:id="@+id/cuo"
        android:layout_width="wrap_content"
        android:layout_height="60dp"
        android:textSize="24dp"
        android:layout_margin="5dp"/>

</LinearLayout>

6、RecycleView的逻辑代码：

package com.me.androidstudy;

import android.app.Activity;
import android.os.Bundle;

import androidx.annotation.Nullable;
import androidx.recyclerview.widget.LinearLayoutManager;
import androidx.recyclerview.widget.RecyclerView;

import com.me.domain.Student;

import java.util.ArrayList;
import java.util.List;

import com.me.adapter.StudentAdapter;

public class Activity_Rec extends Activity {
    RecyclerView studentRec ;
    List<Student> data = new ArrayList<>();
    StudentAdapter adapter = new StudentAdapter();
    public void initView(){
        studentRec = findViewById(R.id.students);
    }
    public void action(){
        for (int i = 0; i < 50; i++) {
            Student student = new Student();
            student.setName("笑天"+i);
            student.setId(20180001+i);
            student.setSex(i%2==0?"男":"女");
            data.add(student);
        }
        adapter.setData(data);
        /**
         *
         * 必须加  studentRec.setLayoutManager(new LinearLayoutManager(this));
         * */
        studentRec.setLayoutManager(new LinearLayoutManager(this));
        studentRec.setAdapter( adapter);
    }
    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.student_rec);
        initView();
        action();
    }
}

7、适配器数据项实体：

package com.me.domain;

public class Student {
    private int id;
    private String name;
    private String sex;

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getSex() {
        return sex;
    }

    public void setSex(String sex) {
        this.sex = sex;
    }

    @Override
    public String toString() {
        return  "学号：" + id +
                "\n姓名：" + name +
                "\n性别：" + sex + "\n";
    }
}

8、适配器的逻辑代码：(RecyclerView.Adapter)

package com.me.adapter;

import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.TextView;

import androidx.annotation.NonNull;
import androidx.recyclerview.widget.RecyclerView;

import com.me.androidstudy.R;
import com.me.domain.Student;

import java.util.ArrayList;
import java.util.List;

public class StudentAdapter extends RecyclerView.Adapter<com.me.adapter.StudentAdapter.MyViewHolder> {
    List<Student> data = new ArrayList<>();

    public void setData(List<Student> data) {
        this.data = data;
        Log.e("rec",data.size()+"");
    }

    @NonNull
    @Override
    public com.me.adapter.StudentAdapter.MyViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
        LayoutInflater layoutInflater = LayoutInflater.from(parent.getContext());
        View itemView = layoutInflater.inflate(R.layout.student_adapter,parent,false);
        return new MyViewHolder(itemView);
    }

    @Override
    public void onBindViewHolder(@NonNull com.me.adapter.StudentAdapter.MyViewHolder holder, int position) {
        Log.e("rec",data.get(position).getName()+"p");
        String text = data.get(position).getName()+"  "+data.get(position).getId()+"  "+data.get(position).getSex();
        holder.info.setText(text);
        if(data.get(position).getSex().equals("男")){
            holder.sex.setBackgroundResource(R.drawable.m1);
        }else{
            holder.sex.setBackgroundResource(R.drawable.f1);
        }
    }

    @Override
    public int getItemCount() {
        return data.size();
    }

    class MyViewHolder extends RecyclerView.ViewHolder{
        TextView info ;
        ImageView sex;
        public MyViewHolder(@NonNull View itemView) {
            super(itemView);
            info = itemView.findViewById(R.id.cuo);
            sex = itemView.findViewById(R.id.sex);
            Log.e("rec",data.get(0).getName());
            Log.e("rec","1234");
        }
    }
}