家庭小账本2.1

DBManger.java

package com.example.famliyaccountbook;
import android.content.*;
import android.database.sqlite.SQLiteDatabase;
import android.database.Cursor;
import android.widget.*;


public class DBManger {
    private Context context;
    private static DBManger instance;
    private String result = "";
    private DBHelper helper;
    // 操作表的对象，进行增删改查
    private SQLiteDatabase writableDatabase;

    public DBManger(Context context) {
        this.context = context;
        DBHelper dbHelper = new DBHelper(context, 1);
        writableDatabase = dbHelper.getWritableDatabase();
    }

    public static DBManger getInstance(Context context) {
        if (instance == null) {
            synchronized (DBManger.class) {
                if (instance == null) {
                    instance = new DBManger(context);
                }
            }
        }
        return instance;
    }

    //增加数据
    public void add(String date, String type, String money) {

        ContentValues contentValues = new ContentValues();
        contentValues.put("date", date);
        contentValues.put("type", type);
        contentValues.put("money", money);

        writableDatabase.insert("bill", null, contentValues);
        writableDatabase.close();

    }

    //根据金额修改数据
    public void update(String money) {
        ContentValues values = new ContentValues();
        values.put("money", money);
        writableDatabase.update("bill", values, "money=?", new String[]{money});
        writableDatabase.close();

    }

    //根据日期删除数据
    public void delete(String date) {
        writableDatabase.delete("bill", "date=?", new String[]{date});
        writableDatabase.close();

    }



}

功能主页面

MainActivity

package com.example.famliyaccountbook;

import androidx.appcompat.app.AppCompatActivity;

import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.view.Window;
import android.widget.Button;

public class MainActivity extends AppCompatActivity {
    private Button button_write;
    private Button button_list;
    private Button button_input;
    private Button button_finish;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        requestWindowFeature(Window.FEATURE_NO_TITLE);
        setContentView(R.layout.activity_main);
        button_write = findViewById(R.id.button_write);
        button_write.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Intent intent = new Intent(MainActivity.this, WriteActivity.class);
                finish();
                startActivity(intent);
            }

        });

        button_list= findViewById(R.id.button_list);
        button_list.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Intent intent = new Intent(MainActivity.this, ListActivity.class);
                finish();
                startActivity(intent);
            }

        });



        button_finish=findViewById(R.id.button_finish);
        button_finish.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                finish();
            }
        });
    }
}

activity_main.xml

<?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"
    android:background="@drawable/main_activity"
    tools:context=".MainActivity">

    <TextView
        android:id="@+id/textView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginStart="171dp"
        android:layout_marginLeft="171dp"
        android:layout_marginTop="131dp"
        android:layout_marginEnd="170dp"
        android:layout_marginRight="170dp"
        android:layout_marginBottom="76dp"
        android:text="家庭小账本"
        app:layout_constraintBottom_toTopOf="@+id/button_write"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <Button
        android:id="@+id/button_write"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginStart="154dp"
        android:layout_marginLeft="154dp"
        android:layout_marginTop="76dp"
        android:layout_marginEnd="153dp"
        android:layout_marginRight="153dp"
        android:layout_marginBottom="40dp"
        android:text="记账"
        app:layout_constraintBottom_toTopOf="@+id/button_list"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/textView" />

    <Button
        android:id="@+id/button_list"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginStart="161dp"
        android:layout_marginLeft="161dp"
        android:layout_marginTop="2dp"
        android:layout_marginEnd="162dp"
        android:layout_marginRight="162dp"
        android:layout_marginBottom="39dp"
        android:text="查看账本"
        app:layout_constraintBottom_toTopOf="@+id/button_finish"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/button_write" />

    <Button
        android:id="@+id/button_finish"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginStart="161dp"
        android:layout_marginLeft="161dp"
        android:layout_marginEnd="162dp"
        android:layout_marginRight="162dp"
        android:layout_marginBottom="243dp"
        android:text="退出系统"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/button_list" />

</androidx.constraintlayout.widget.ConstraintLayout>