基于Java实现一个简单的单词本Android App的实践

        本文基于java实现了一个简单的单词本安卓app，用的是sqlite数据库，包括布局文件、源码及实现图。

布局设计

单词本主界面

<?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"
    android:orientation="vertical"
    tools:context=".adddanciactivity">
 
    <edittext
        android:id="@+id/addword_edit"
        android:layout_width="match_parent"
        android:layout_height="60dp"
        android:layout_margintop="20dp"
        android:hint="单词:"
        android:textcolor="@android:color/black"
        android:textcolorhint="#dcdcdc"
        android:textsize="30dp" />
 
    <edittext
        android:id="@+id/fanyiword_edit"
        android:layout_width="match_parent"
        android:layout_height="60dp"
        android:hint="解释:"
        android:textcolor="@android:color/black"
        android:textcolorhint="#dcdcdc"
        android:textsize="30dp" />
 
    <relativelayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_alignparentbottom = "true"
        android:layout_margin="5dp">
    <listview
        android:id="@+id/add_list"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:textcolor="@android:color/black"
        android:textcolorhint="#dcdcdc"
        android:textsize="30dp"
        android:layout_above="@id/linelayout"
        />
 
        <linearlayout
            android:layout_height="50dp"
            android:layout_width="match_parent"
            android:id="@+id/linelayout"
            android:layout_alignparentbottom="true"
            android:orientation="horizontal"
            android:gravity="center_horizontal"
            >
        <button
            android:layout_width="100dp"
            android:layout_height="50dp"
            android:id="@+id/add_btn"
            android:text="添加" />
        <button
            android:layout_width="100dp"
            android:layout_height="50dp"
            android:layout_centerhorizontal="true"
            android:id="@+id/shanchu_btn"
            android:layout_gravity="center_vertical"
            android:text="删除" />
        <button
            android:layout_width="100dp"
            android:layout_height="50dp"
            android:id="@+id/quxiao_btn"
            android:layout_gravity="right"
            android:text="取消" />
        </linearlayout>
 
    </relativelayout>
 
</linearlayout>

代码

adddanciactivity.java

        单词本主界面的activity

import androidx.appcompat.app.appcompatactivity;
import android.content.contentvalues;
import android.database.cursor;
import android.database.sqlite.sqlitedatabase;
import android.os.bundle;
import android.view.view;
import android.widget.button;
import android.widget.edittext;
import android.widget.listview;
import android.widget.simpleadapter;
import android.widget.toast;
import java.util.arraylist;
import java.util.hashmap;
import java.util.map;
 
public class adddanciactivity extends appcompatactivity {
 
    private edittext wordedit;
    private edittext yisiedit;
    private button add_btn;
    private button quxiao_btn;
    private button shanchu_btn;
    private listview listview;
    private dbopenhelper dbopenhelper;//声明
 
    @override
    protected void oncreate(bundle savedinstancestate) {
        super.oncreate(savedinstancestate);
        setcontentview(r.layout.activity_add_danci);
        dbopenhelper = new dbopenhelper(adddanciactivity.this, "db_dict", null, 1);//实例化，创建数据库
        wordedit = (edittext) findviewbyid(r.id.addword_edit);
        yisiedit = (edittext) findviewbyid(r.id.fanyiword_edit);
        listview = (listview) findviewbyid(r.id.add_list);
        add_btn = (button) findviewbyid(r.id.add_btn);
        quxiao_btn = (button) findviewbyid(r.id.quxiao_btn);
        shanchu_btn = (button) findviewbyid(r.id.shanchu_btn);
        quxiao_btn.setonclicklistener(new view.onclicklistener() {
            @override
            public void onclick(view v) {
                toast.maketext(adddanciactivity.this, "返回单词本主界面", toast.length_short).show();
                finish();
            }
        });
 
        shanchu_btn.setonclicklistener(new view.onclicklistener() {
            @override
            public void onclick(view v) {
                string word = wordedit.gettext().tostring();
                string ys = yisiedit.gettext().tostring();
                if (word.equals("")) {
                    toast.maketext(adddanciactivity.this, "填写的单词为空", toast.length_short).show();
                } else {
                    deletedata(dbopenhelper.getreadabledatabase(), word);
                    toast.maketext(adddanciactivity.this, "删除成功", toast.length_short).show();
                }
            }
        });
 
        add_btn.setonclicklistener(new view.onclicklistener() {
            @override
            public void onclick(view v) {
                string word = wordedit.gettext().tostring();
                string ys = yisiedit.gettext().tostring();
                if (word.equals("") || ys.equals("")) {
                    toast.maketext(adddanciactivity.this, "填写的单词或解释为空", toast.length_short).show();
                } else {
                    insertdata(dbopenhelper.getreadabledatabase(), word, ys);//插入生词
                    toast.maketext(adddanciactivity.this, "添加生词成功", toast.length_short).show();
                    renew();
                }
            }
        });
    }
 
    //插入数据的方法
    private void insertdata(sqlitedatabase sqlitedatabase, string word, string ys) {
        contentvalues values = new contentvalues();
        values.put("word", word);//保存单词
        values.put("detail", ys);
        sqlitedatabase.insert("tb_dict", null, values);//执行插入操作
        renew();
    }
 
    private void deletedata(sqlitedatabase sqlitedatabase, string word) {
        contentvalues values = new contentvalues();
        string[] args = {string.valueof(word)};
        sqlitedatabase.delete("tb_dict", "word=?", args);//执行删除操作
        renew();
    }
 
 
    @override
    protected void ondestroy() {
        super.ondestroy();
        if (dbopenhelper != null) {
            dbopenhelper.close();//关闭
        }
    }
 
    public void renew() {
        cursor cursor = dbopenhelper.getreadabledatabase().query("tb_dict", null, null, null, null, null, null);
        arraylist<map<string, string>> resultlist = new arraylist<map<string, string>>();
        while (cursor.movetonext()) {
            map<string, string> map = new hashmap<string, string>();
            map.put("word", cursor.getstring(1));
            map.put("interpret", cursor.getstring(2));
            resultlist.add(map);
        }
 
        if (resultlist == null || resultlist.size() == 0) {
            toast.maketext(adddanciactivity.this, "很遗憾，没有相关记录！", toast.length_short).show();
        } else {
            simpleadapter simpleadapter = new simpleadapter(adddanciactivity.this, resultlist, r.layout.item, new string[]{"word", "interpret"
            }, new int[]{r.id.textview, r.id.textview2});
            listview.setadapter(simpleadapter);
        }
    }
 
    @override
    protected void onstart() {
        super.onstart();
        renew();
    }
}

dbopenhelper.java

用到的是sqlite数据库，android自带了一种轻量级数据库，使用非常方便。

import android.content.context;
import android.database.sqlite.sqlitedatabase;
import android.database.sqlite.sqliteopenhelper;
import android.util.log;
import androidx.annotation.nullable;
 
public class dbopenhelper extends sqliteopenhelper {
 
    final string create_table_sql = "create table tb_dict (_id integer primary key autoincrement,word,detail)";//定义创建表的
 
    public dbopenhelper(@nullable context context, @nullable string name, @nullable sqlitedatabase.cursorfactory factory, int version) {
        super(context, name, null, version);
    }
 
    @override
    public void oncreate(sqlitedatabase db) {
        db.execsql(create_table_sql);//创建单词的数据表
    }
 
    @override
    public void onupgrade(sqlitedatabase db, int oldversion, int newversion) {
        log.i("词典", "--版本更新" + oldversion + "-->" + newversion);
    }
}

效果图

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