Android每点击一次按钮就添加一条数据

package top.gaojc.calculator.domain;

public class Data {
    private int imgId;
    private String content;

    public Data() {}

    public Data(int imgId, String content) {
        this.imgId = imgId;
        this.content = content;
    }

    public int getImgId() {
        return imgId;
    }

    public String getContent() {
        return content;
    }

    public void setImgId(int imgId) {
        this.imgId = imgId;
    }

    public void setContent(String content) {
        this.content = content;
    }

}

package top.gaojc.calculator;

import androidx.appcompat.app.AppCompatActivity;

import android.content.Context;
import android.os.Bundle;
import android.provider.ContactsContract;
import android.view.View;
import android.widget.Button;
import android.widget.ListView;

import java.util.LinkedList;
import java.util.List;

import top.gaojc.calculator.domain.Data;

public class MainActivity extends AppCompatActivity implements View.OnClickListener {

    // 初始化
    Button btn_add;

    int flag = 1;

    private ListView list_one;
    private MyAdapter mAdapter = null;
    private List<Data> mData = null;
    private Context mContext = null;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);


        mContext = MainActivity.this;
        bindViews();
        mData = new LinkedList<Data>();
        mAdapter = new MyAdapter((LinkedList<Data>) mData,mContext);
        list_one.setAdapter(mAdapter);


        btn_add = findViewById(R.id.btn_add);
        btn_add.setOnClickListener(this);

    }

    private void bindViews(){
        list_one = (ListView) findViewById(R.id.list_one);
    }


    @Override
    public void onClick(View view) {
        switch (view.getId()){
            case R.id.btn_add:
                mAdapter.add(new Data(R.drawable.girl,"想你想你想我！！！ × " + flag));
                flag++;
                break;
        }
    }
}

package top.gaojc.calculator;

import android.content.Context;
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 java.util.LinkedList;

import top.gaojc.calculator.domain.Data;

public class MyAdapter extends BaseAdapter {

    private Context mContext;
    private LinkedList<Data> mData;

    public MyAdapter() {}

    public MyAdapter(LinkedList<Data> mData, Context mContext) {
        this.mData = mData;
        this.mContext = mContext;
    }

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

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

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

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        ViewHolder holder = null;
        if(convertView == null){
            convertView = LayoutInflater.from(mContext).inflate(R.layout.item_list,parent,false);
            holder = new ViewHolder();
            holder.img_icon = (ImageView) convertView.findViewById(R.id.img_icon);
            holder.txt_content = (TextView) convertView.findViewById(R.id.txt_content);
            convertView.setTag(holder);
        }else{
            holder = (ViewHolder) convertView.getTag();
        }
        holder.img_icon.setImageResource(mData.get(position).getImgId());
        holder.txt_content.setText(mData.get(position).getContent());
        return convertView;
    }

    private class ViewHolder{
        ImageView img_icon;
        TextView txt_content;
    }


    public void add(Data data) {
        if (mData == null) {
            mData = new LinkedList<>();
        }
        mData.add(data);
        notifyDataSetChanged();
    }
}

<?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"
    android:orientation="vertical">

    <Button
        android:id="@+id/btn_add"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="添加数据"/>

    <ListView
        android:id="@+id/list_one"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" />
</LinearLayout>

<?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/img_icon"
        android:layout_width="56dp"
        android:layout_height="56dp"/>

    <TextView
        android:id="@+id/txt_content"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="20dp"
        android:layout_marginLeft="10dp"
        android:textSize="18sp" />

</LinearLayout>

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="top.gaojc.calculator">

    <application
        android:allowBackup="true"
        android:icon="@drawable/girl"
        android:label="@string/app_name"
        android:roundIcon="@drawable/girl"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">
        <activity android:name=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>