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  • 通讯录

    activity_main.xml

    <?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:background="@drawable/bg"
        android:orientation="vertical"
        android:padding="16dp" >
    
        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_marginTop="130dp" >
    
            <TextView
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:text="姓  名 :"
                android:textSize="18sp" />
    
            <EditText
                android:id="@+id/et_name"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:hint="请输入姓名"
                android:textSize="16sp" />
        </LinearLayout>
    
        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_marginBottom="10dp" >
    
            <TextView
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:text="年  龄:"
                android:textSize="18sp" />
    
            <EditText
                android:id="@+id/et_age"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:hint="请输入年龄"
                android:textSize="16sp" />
        </LinearLayout>
    
        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="wrap_content" >
    
            <Button
                android:id="@+id/btn_add"
                android:layout_width="0dp"
                android:layout_height="wrap_content"
                android:layout_marginRight="2dp"
                android:layout_weight="1"
                android:background="#B9B9FF"
                android:onClick="add"
                android:text="添加"
                android:textSize="18sp" />
    
            <Button
                android:id="@+id/btn_query"
                android:layout_width="0dp"
                android:layout_height="wrap_content"
                android:layout_marginRight="2dp"
                android:layout_weight="1"
                android:background="#DCB5FF"
                android:onClick="search"
                android:text="查询"
                android:textSize="18sp" />
    
            <Button
                android:id="@+id/btn_update"
                android:layout_width="0dp"
                android:layout_height="wrap_content"
                android:layout_marginRight="2dp"
                android:layout_weight="1"
                android:background="#E6CAFF"
                android:onClick="update"
                android:text="修改"
                android:textSize="18sp" />
    
            <Button
                android:id="@+id/btn_delete"
                android:layout_width="0dp"
                android:layout_height="wrap_content"
                android:layout_weight="1"
                android:background="#ACD6FF"
                android:onClick="delete"
                android:text="删除"
                android:textSize="18sp" />
        </LinearLayout>
    
        <ScrollView
            android:layout_width="match_parent"
            android:layout_height="wrap_content" >
    
            <TextView
                android:id="@+id/tv_show"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:layout_marginTop="25dp"
                android:textSize="20sp" />
        </ScrollView>
    
    </LinearLayout>

    MainActivity.java

    package com.example.myaddressbook;
    
    import androidx.appcompat.app.AppCompatActivity;
    
    import android.database.Cursor;
    import android.database.sqlite.SQLiteDatabase;
    import android.os.Bundle;
    import android.view.View;
    import android.widget.EditText;
    import android.widget.TextView;
    import android.widget.Toast;
    
    public class MainActivity extends AppCompatActivity {
    
        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_main);
        }
    
        public void add(View v){
            StuOpenHelper helper=new StuOpenHelper(this);
            SQLiteDatabase db=helper.getWritableDatabase();
            String name=((EditText)findViewById(R.id.et_name)).getText().toString();
            int age=Integer.parseInt(((EditText)findViewById(R.id.et_age)).getText().toString());
    
            db.execSQL("insert into stuinfo(name,age) values(?,?)",new Object[]{
                    name,age
            });
            Toast.makeText(this,"ok",Toast.LENGTH_LONG).show();
        }
    
        public void delete(View view) {
            StuOpenHelper helper = new StuOpenHelper(this);
            SQLiteDatabase db = helper.getWritableDatabase();
            db.execSQL("delete from stuinfo where _id=?",new Object[]{2});
            Toast.makeText(this,"修改成功",Toast.LENGTH_LONG).show();
        }
    
        public void update(View view) {
            StuOpenHelper helper = new StuOpenHelper(this);
            SQLiteDatabase db = helper.getWritableDatabase();
            db.execSQL("update stuinfo set name=? where _id=?",new Object[]{
                    "Mickey",3
            });
            Toast.makeText(this,"修改成功",Toast.LENGTH_LONG).show();
        }
    
        public void search(View view) {
            StuOpenHelper helper = new StuOpenHelper(this);
            SQLiteDatabase db = helper.getWritableDatabase();
            String s="";
            Cursor cursor=db.rawQuery("select * from stuinfo",null);
            if(cursor.getCount() !=0){
                while(cursor.moveToNext()){
                    s +=cursor.getInt(0)+"     "+cursor.getString(1)+"    "+cursor.getInt(2)+"
    ";
                }
            }
            ((TextView)(findViewById(R.id.tv_show))).setText(s);
        }
    }

    StuOpenHelper.java

    package com.example.myaddressbook;
    
    import android.content.Context;
    import android.database.sqlite.SQLiteDatabase;
    import android.database.sqlite.SQLiteOpenHelper;
    
    import androidx.annotation.Nullable;
    
    public class StuOpenHelper extends SQLiteOpenHelper {
        public StuOpenHelper(@Nullable Context context) {
            super(context,"stu.db", null, 1);
        }
    
        @Override
        public void onCreate(SQLiteDatabase db) {
            db.execSQL("create table stuinfo(_id integer primary key autoincrement,name varchar(20),age integer)");
        }
    
        @Override
        public void onUpgrade(SQLiteDatabase sqLiteDatabase, int i, int i1) {
    
        }
    }
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  • 原文地址:https://www.cnblogs.com/w200100/p/14099296.html
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