2021.3.8

在Java里新建项目，命名为new_cost.java：

package com.example.myaccountapp;

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;

import java.text.SimpleDateFormat;
import java.util.Date;

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();
}

}
}