基于Java怎样实现一个简单的单词本Android App

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布局设计

单词本主界面

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> resultList = new ArrayList>();        while (cursor.moveToNext()) {            Map map = new HashMap();            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

Java的特点有哪些

Java的特点有哪些 1.Java语言作为静态面向对象编程语言的代表，实现了面向对象理论，允许程序员以优雅的思维方式进行复杂的编程。 2.Java具有简单性、面向对象、分布式、安全性、平台独立与可移植性、动态性等特点。 3.使用Java可以编写桌面应用程序、Web应用程序、分布式系统和嵌入式系统应用程序等。

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