记账本实现添加功能

我们在MainActivity.java里面写了addAccount，即添加功能，点击加号跳转到一个新的页面，之后完成想要执行的操作，然后具体执行的操作我们写在new_cost.java里面

package com.example.cashBook;

import androidx.appcompat.app.AppCompatActivity;

import android.content.ContentValues;
import android.database.sqlite.SQLiteDatabase;
import android.os.Bundle;
import android.view.Gravity;
import android.view.View;
import android.widget.DatePicker;
import android.widget.EditText;
import android.widget.Toast;

public class new_cost extends AppCompatActivity {
    private DBHelper helper;
    private EditText et_cost_title;
    private EditText et_cost_money;
    private DatePicker dp_cost_date;

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

    private void initView() {
        helper = new DBHelper(new_cost.this);
        et_cost_title = findViewById(R.id.et_cost_title);
        et_cost_money = findViewById(R.id.et_cost_money);
        dp_cost_date = findViewById(R.id.dp_cost_date);

    }


    public void okButton(View view) {
        String titleStr = et_cost_title.getText().toString().trim();
        String moneyStr = et_cost_money.getText().toString().trim();
        String dateStr = dp_cost_date.getYear() + "-" + (dp_cost_date.getMonth() + 1) + "-"
                + dp_cost_date.getDayOfMonth();//这里getMonth会比当前月份少一个月，所以要+1
        if ("".equals(moneyStr)) {//可以不填写Title但是不能不填金额
            Toast toast = Toast.makeText(this, "请填写金额", Toast.LENGTH_SHORT);
            toast.setGravity(Gravity.CENTER, 0, 0);
            toast.show();
        } else {
            SQLiteDatabase db = helper.getWritableDatabase();
            ContentValues values = new ContentValues();
            values.put("Title", titleStr);
            values.put("Money", moneyStr);
            values.put("Date", dateStr);
            long account = db.insert("account", null, values);
            if (account > 0) {
                Toast toast = Toast.makeText(this, "保存成功", Toast.LENGTH_SHORT);
                toast.setGravity(Gravity.CENTER, 0, 0);
                toast.show();
                setResult(1);
                finish();
            } else {
                Toast toast = Toast.makeText(this, "请重试", Toast.LENGTH_SHORT);
                toast.setGravity(Gravity.CENTER, 0, 0);
                toast.show();
                db.close();
            }
            setResult(1);
            finish();
        }

    }
}

将new_cost写好之后，然后会在layout里面写一个activity_new_cost.xml文件，就是页面布局文件（同时生成new_cost文件和activity_new_cost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="match_parent"
    android:orientation="vertical"
    android:gravity="center">

    <EditText
        android:id="@+id/et_cost_title"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_margin="4dp"
        android:hint="Cost Title"
        android:textColor="#ffbd27"
        />

    <EditText
        android:id="@+id/et_cost_money"
        android:inputType="number|numberDecimal"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_margin="4dp"
        android:hint="Cost Money"
        android:textColor="#ffbd27"
        />

    <DatePicker
        android:id="@+id/dp_cost_date"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_margin="8dp"
        android:datePickerMode="spinner"
        android:calendarViewShown="false"
        />

    <Button
        android:onClick="okButton"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="确认"
        android:textSize="20dp"
        android:textColor="#333333"
        android:background="#ffbd27"
        android:layout_marginLeft="40dp"
        android:layout_marginRight="40dp"
        />
LinearLayout>