家庭小账本——适配器的编写与测试

　　　　今天开始根据网络教学进行家庭小账本的编写，然后进行测试，这是第一次编写较为完善全面的Android的程序，而且作为Android的初学者，自我感觉这次编写非常的慢，有许多的方面都没有比较满意的进行，而且这次综合的知识的也不少。

　　　　先进行界面的设计，

<?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"
    app:layout_behavior="@string/appbar_scrolling_view_behavior"
    tools:context=".MainActivity"
    tools:showIn="@layout/activity_main">

    <ListView
        android:id="@+id/lv_main"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />

</androidx.constraintlayout.widget.ConstraintLayout>

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical" android:layout_width="match_parent"
    android:layout_height="80dp">

    <TextView
        android:id="@+id/tv_title"
        android:layout_marginLeft="10dp"
        android:gravity="center"
        android:singleLine="true"
        android:textSize="35sp"
        android:ellipsize="marquee"
        android:text="CostTitle"
        android:layout_width="100dp"
        android:layout_height="85dp"/>
    <TextView
        android:id="@+id/tv_date"
        android:text="costdate"
        android:layout_width="wrap_content"
        android:gravity="center"
        android:textSize="20sp"
        android:layout_marginLeft="15dp"
        android:layout_toRightOf="@id/tv_title"
        android:layout_height="80dp"/>
    <TextView
        android:id="@+id/tv_cost"
        android:gravity="center"
        android:layout_alignParentRight="true"
        android:layout_marginRight="20dp"
        android:textSize="30sp"
        android:text="30"
        android:layout_width="wrap_content"
        android:layout_height="80dp"/>
</RelativeLayout>

设置了一个相对布局，共有三列，分别为日期，金额，日期。

然后添加一个Java类CostListAdapter，并添加内容

package com.example.familyledger;

import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.TextView;

import java.util.List;

public class CostListAdapter extends BaseAdapter {
    private List<CostBean> mList;
    private Context mContext;
    private LayoutInflater mLayoutInflater;

    public CostListAdapter(Context context,List<CostBean>list){
        mContext=context;
        mList=list;
        mLayoutInflater=LayoutInflater.from(context);
    }
    @Override
    public int getCount() {
        return mList.size();
    }

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

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

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        ViewHolder viewHolder;
        if(convertView==null)
        {
            viewHolder=new ViewHolder();
            convertView=mLayoutInflater.inflate(R.layout.list_item,null);
            viewHolder.mTvCostTitle=(TextView)convertView.findViewById(R.id.tv_title);
            viewHolder.mTvCostDate=(TextView)convertView.findViewById(R.id.tv_date);
            viewHolder.mtvCostMoney=(TextView)convertView.findViewById(R.id.tv_cost);
            convertView.setTag(viewHolder);
        }else
        {
            viewHolder=(ViewHolder)convertView.getTag();
        }
        CostBean bean=mList.get(position);
        viewHolder.mTvCostTitle.setText(bean.costTitle);
        viewHolder.mtvCostMoney.setText(bean.costMoney);
        viewHolder.mTvCostDate.setText(bean.costDate);
        return convertView;
    }
    public static class ViewHolder{
        public TextView mTvCostTitle;
        public TextView mTvCostDate;
        public TextView mtvCostMoney;
    }
}

最后在添加一个Bean类

package com.example.familyledger;

public class CostBean {
    public String costTitle;
    public String costDate;
    public String costMoney;
}

最后在MainActivity中设计主函数

package com.example.familyledger;

import android.os.Bundle;

import com.google.android.material.floatingactionbutton.FloatingActionButton;
import com.google.android.material.snackbar.Snackbar;

import androidx.appcompat.app.AppCompatActivity;
import androidx.appcompat.widget.Toolbar;

import android.view.View;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.ListView;

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

public class MainActivity extends AppCompatActivity {

    private List<CostBean> mCostListBean;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Toolbar toolbar = findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);

        mCostListBean=new ArrayList<>();
        ListView costList=(ListView)findViewById(R.id.lv_main);
        initCostdata();
        costList.setAdapter(new CostListAdapter(this,mCostListBean));

        FloatingActionButton fab = findViewById(R.id.fab);
        fab.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
                        .setAction("Action", null).show();
            }
        });
    }

    private void initCostdata() {
        for (int i=0;i<6;i++) {
            CostBean costBean1=new CostBean();
            costBean1.costDate="11-11";
            costBean1.costMoney="20";
            costBean1.costTitle="mock";
            mCostListBean.add(costBean1);
        }
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.menu_main, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();

        //noinspection SimplifiableIfStatement
        if (id == R.id.action_settings) {
            return true;
        }

        return super.onOptionsItemSelected(item);
    }
}

最后显示测试画面，有五行的相同自定义的数据