如何解析 "Cannot resolve method 'Insertdata'" in Java？

Question

我正在尝试将数据插入 SQLite。但是 AddActivity.java 中有些问题。我的概念是将数据插入 SQLite。从数据显示列表中读取数据后。

当点击数据列表中的列表时，将显示该列表的详细信息。

这里是错误：

Cannot resolve method 'Insertdata(java.lang.String,java.lang.String,java.lang.String)'

myDBClass.java

package com.example.puen.projectdemo;

import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.util.Log;

import java.util.ArrayList;
import java.util.HashMap;

public class myDBClass extends SQLiteOpenHelper {


    // Database Version
    private static final int DATABASE_VERSION = 1;

    // Database Name
    private static final String DATABASE_NAME = "mydatabase";

    // Table Name
    private static final String TABLE_MEMBER = "members";

    public myDBClass(Context context) {
        super(context, DATABASE_NAME, null, DATABASE_VERSION);
        // TODO Auto-generated constructor stub
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
        // TODO Auto-generated method stub
        // Create Table Name
        db.execSQL("CREATE TABLE " + TABLE_MEMBER +
                "(MemberID INTEGER PRIMARY KEY AUTOINCREMENT," +
                " Name TEXT(100)," +
                " Tel TEXT(100));");

        Log.d("CREATE TABLE", "Create Table Successfully.");
    }


    // Select Data
    public String[] SelectData(String strMemberID) {
        // TODO Auto-generated method stub

        try {
            String arrData[] = null;

            SQLiteDatabase db;
            db = this.getReadableDatabase(); // Read Data

            Cursor cursor = db.query(TABLE_MEMBER, new String[]{"*"},
                    "MemberID=?",
                    new String[]{String.valueOf(strMemberID)}, null, null, null, null);

            if(cursor != null)
            {
                if (cursor.moveToFirst()) {
                    arrData = new String[cursor.getColumnCount()];
                    /***
                     *  0 = MemberID
                     *  1 = Name
                     *  2 = Tel
                     */
                    arrData[0] = cursor.getString(0);
                    arrData[1] = cursor.getString(1);
                    arrData[2] = cursor.getString(2);
                }
            }
            cursor.close();
            db.close();
            return arrData;

        } catch (Exception e) {
            return null;
        }

    }

    // Show All Data
    public ArrayList<HashMap<String, String>> SelectAllData() {
        // TODO Auto-generated method stub

        try {

            ArrayList<HashMap<String, String>> MyArrList = new ArrayList<>();
            HashMap<String, String> map;

            SQLiteDatabase db;
            db = this.getReadableDatabase(); // Read Data

            String strSQL = "SELECT  * FROM " + TABLE_MEMBER;
            Cursor cursor = db.rawQuery(strSQL, null);

            if(cursor != null)
            {
                if (cursor.moveToFirst()) {
                    do {
                        map = new HashMap<>();
                        map.put("MemberID", cursor.getString(0));
                        map.put("Name", cursor.getString(1));
                        map.put("Tel", cursor.getString(2));
                        MyArrList.add(map);
                    } while (cursor.moveToNext());
                }
            }
            cursor.close();
            db.close();
            return MyArrList;

        } catch (Exception e) {
            return null;
        }

    }



    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        // TODO Auto-generated method stub
        db.execSQL("DROP TABLE IF EXISTS " + TABLE_MEMBER);

        // Re Create on method  onCreate
        onCreate(db);
    }


}

AddActivity.java

package com.example.puen.projectdemo;

import android.app.Activity;
import android.app.AlertDialog;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;
import android.app.Activity;
import android.app.AlertDialog;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;

public class AddActivity extends Activity  {

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_add);


        // btnSave (Save)
        final Button save = (Button) findViewById(R.id.btnSave);
        save.setOnClickListener(new View.OnClickListener() {
            public void onClick(View v) {

                // If Save Complete
                if(SaveData())
                {
                    // Open Form Main
                    Intent newActivity = new Intent(AddActivity.this,MainActivity.class);
                    startActivity(newActivity);
                }
            }
        });


        // btnCancel (Cancel)
        final Button cancel = (Button) findViewById(R.id.btnCancel);
        cancel.setOnClickListener(new View.OnClickListener() {
            public void onClick(View v) {
                // Open Form Main
                Intent newActivity = new Intent(AddActivity.this,MainActivity.class);
                startActivity(newActivity);
            }
        });

    }

    public boolean SaveData()
    {
        // txtMemberID, txtName, txtTel
        final EditText tMemberID = (EditText) findViewById(R.id.txtMemberID);
        final EditText tName = (EditText) findViewById(R.id.txtName);
        final EditText tTel = (EditText) findViewById(R.id.txtTel);

        // Dialog
        final AlertDialog.Builder adb = new AlertDialog.Builder(this);
        AlertDialog ad = adb.create();

        // Check MemberID
        if(tMemberID.getText().length() == 0)
        {
            ad.setMessage("Please input [MemberID] ");
            ad.show();
            tMemberID.requestFocus();
            return false;
        }

        // Check Name
        if(tName.getText().length() == 0)
        {
            ad.setMessage("Please input [Name] ");
            ad.show();
            tName.requestFocus();
            return false;
        }

        // Check Tel
        if(tTel.getText().length() == 0)
        {
            ad.setMessage("Please input [Tel] ");
            ad.show();
            tTel.requestFocus();
            return false;
        }

        // new Class DB
        final myDBClass myDb = new myDBClass(this);

        // Check Data (MemberID exists)
        String arrData[] = myDb.SelectData(tMemberID.getText().toString());
        if(arrData != null)
        {
            ad.setMessage("MemberID already exists!  ");
            ad.show();
            tMemberID.requestFocus();
            return false;
        }

        // Save Data
        long saveStatus = myDb.InsertData(tMemberID.getText().toString(),
                tName.getText().toString(),
                tTel.getText().toString());
        if(saveStatus <=  0)
        {
            ad.setMessage("Error!! ");
            ad.show();
            return false;
        }

        Toast.makeText(AddActivity.this,"Add Data Successfully. ",
                Toast.LENGTH_SHORT).show();

        return true;
    }

}

DetailActivity.java

package com.example.puen.projectdemo;

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;

public class DetailActivity extends Activity  {

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_detail);

        // Read var from Intent
        Intent intent= getIntent();
        String MemID = intent.getStringExtra("MemID");

        // Show Data
        ShowData(MemID);

        // btnCancel (Cancel)
        final Button cancel = (Button) findViewById(R.id.btnCancel);
        cancel.setOnClickListener(new View.OnClickListener() {
            public void onClick(View v) {
                // Open Form Show
                Intent newActivity = new Intent(DetailActivity.this,ShowActivity.class);
                startActivity(newActivity);
            }
        });

    }

    public void ShowData(String MemID)
    {
        // txtMemberID, txtName, txtTel
        final TextView tMemberID = (TextView) findViewById(R.id.txtMemberID);
        final TextView tName = (TextView) findViewById(R.id.txtName);
        final TextView tTel = (TextView) findViewById(R.id.txtTel);

        // new Class DB
        final myDBClass myDb = new myDBClass(this);

        // Show Data
        String arrData[] = myDb.SelectData(MemID);
        if(arrData != null)
        {
            tMemberID.setText(arrData[0]);
            tName.setText(arrData[1]);
            tTel.setText(arrData[2]);
        }

    }

}

ShowActivity.java

package com.example.puen.projectdemo;

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.Button;
import android.widget.ListView;
import android.widget.SimpleAdapter;

import java.util.ArrayList;
import java.util.HashMap;

public class ShowActivity extends Activity  {

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_show);

        final myDBClass myDb = new myDBClass(this);
        final ArrayList<HashMap<String, String>> MebmerList = myDb.SelectAllData();

        // listView1
        ListView lisView1 = (ListView)findViewById(R.id.listView1);

        SimpleAdapter sAdap;
        sAdap = new SimpleAdapter(ShowActivity.this, MebmerList, R.layout.activity_column,
                new String[] {"MemberID", "Name", "Tel"}, new int[] {R.id.ColMemberID, R.id.ColName, R.id.ColTel});
        lisView1.setAdapter(sAdap);

        lisView1.setOnItemClickListener(new OnItemClickListener() {
            public void onItemClick(AdapterView<?> myAdapter, View myView, int position, long mylng) {

                // Show on new activity
                Intent newActivity = new Intent(ShowActivity.this,DetailActivity.class);
                newActivity.putExtra("MemID", MebmerList.get(position).get("MemberID").toString());
                startActivity(newActivity);

            }
        });


        // btnCancel (Cancel)
        final Button cancel = (Button) findViewById(R.id.btnCancel);
        cancel.setOnClickListener(new View.OnClickListener() {
            public void onClick(View v) {
                // Open Form Main
                Intent newActivity = new Intent(ShowActivity.this,MainActivity.class);
                startActivity(newActivity);
            }
        });

    }


}

Answer 1

您的 myDBClass 中没有 Insertdata 方法。您正在调用尚未初始化的内容。

Answer 2

class"myDBClass"中没有"InsertData"这样的方法。您应该将 InsertData 方法添加到 myDBClass，并在该方法中添加插入数据库的逻辑。

如何解析 "Cannot resolve method 'Insertdata'" in Java？

How to resolve "Cannot resolve method 'Insertdata'" in Java?

sqlite

android

crud

lang

android-studio