小贝子编程

ID value returning null



我是Android编程的新手，并希望通过单击"更新"按钮来更新数据库中的记录时，请有一些帮助或建议。是无效的，所以它不会更新。我如何获得它，以使ID在更新时不会为null。

databasehelper.java 

package com.example.warre.sqlliteapp;
import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
public class DatabaseHelper extends SQLiteOpenHelper {
public static final String DATABASE_NAME = "tracker.db";
public static final String TABLE_NAME = "tracker_table";
public static final String COL_1 = "ID";
public static final String COL_2 = "SALES";
public static final String COL_3 = "FOLLOW";
public static final String COL_4 = "DONE";
public static final String COL_5 = "LEADER";
public static final String COL_6 = "TRAIN";
public DatabaseHelper(Context context) {
    super(context, DATABASE_NAME, null, 1);
}
@Override
public void onCreate(SQLiteDatabase db) {
    db.execSQL("create table " + TABLE_NAME +" (ID INTEGER PRIMARY KEY AUTOINCREMENT,SALES INTEGER,FOLLOW INTEGER,DONE INTEGER, LEADER INTEGER, TRAIN INTEGER)");
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
    db.execSQL("DROP TABLE IF EXISTS "+TABLE_NAME);
    onCreate(db);
}
public boolean insertData(String sales,String follow,String done, String leader, String train) {
    SQLiteDatabase db = this.getWritableDatabase();
    ContentValues contentValues = new ContentValues();
    contentValues.put(COL_2,sales);
    contentValues.put(COL_3,follow);
    contentValues.put(COL_4,done);
    contentValues.put(COL_5,leader);
    contentValues.put(COL_6, train);
    long result = db.insert(TABLE_NAME,null ,contentValues);
    if(result == -1)
        return false;
    else
        return true;
}
public Cursor getAllData() {
    SQLiteDatabase db = this.getWritableDatabase();
    Cursor res = db.rawQuery("select * from "+TABLE_NAME,null);
    return res;
}
public boolean updateData(String id,String sales,String follow,String done, String leader, String train) {
    SQLiteDatabase db = this.getWritableDatabase();
    ContentValues contentValues = new ContentValues();
    contentValues.put(COL_1,id);
    contentValues.put(COL_2,sales);
    contentValues.put(COL_3,follow);
    contentValues.put(COL_4,done);
    contentValues.put(COL_5, leader);
    contentValues.put(COL_6, train);
    db.update(TABLE_NAME, contentValues, "ID = ?",new String[] { id });
    return true;
}
public Integer deleteData (String id) {
    SQLiteDatabase db = this.getWritableDatabase();
    return db.delete(TABLE_NAME, "ID = ?",new String[] {id});
}
}

MainActivity

问题正在在更新((中发生的eDittextId恢复为null或返回null。

package com.example.warre.sqlliteapp;
import android.app.Activity;
import android.database.Cursor;
import android.os.Handler;
import android.support.v7.app.AlertDialog;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;
import java.util.Timer;
import java.util.TimerTask;
public class MainActivity extends Activity {
DatabaseHelper myDb;
EditText editTextId;
TextView txtSales,txtFollow,txtDone,txtLeader,txtTrain, TimerValue;
Button btnAddData;
Button btnviewAll;
Button btnDelete;
Button SALES,FOLLOW,DONE,LEADER,TRAIN, STOP, REPORT;
int countSales = 0;
int countFollow = 0;
int countDone = 0;
int nCounter = 0;
String timeName;
TimerTask mTimerTask;
final Handler handler = new Handler();
Timer t = new Timer();
Button btnviewUpdate;
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_money);
    myDb = new DatabaseHelper(this);
    TimerValue = (TextView) findViewById(R.id.tv_current_timeV2);
    txtSales = (TextView) findViewById(R.id.textSales);
    txtFollow = (TextView) findViewById(R.id.textFollow);
    txtDone = (TextView) findViewById(R.id.textDone);
    txtLeader = (TextView) findViewById(R.id.leaderTime);
    txtTrain = (TextView) findViewById(R.id.trainTime);
    SALES = (Button) findViewById(R.id.btnSales);
    FOLLOW = (Button) findViewById(R.id.btnFollow);
    DONE = (Button) findViewById(R.id.btnDone);
    LEADER = (Button) findViewById(R.id.btnLeader);
    TRAIN = (Button) findViewById(R.id.btnTrain);
    STOP = (Button) findViewById(R.id.btnStop);
    REPORT = (Button) findViewById(R.id.button_details);

    editTextId = (EditText)findViewById(R.id.editText_id);
    btnAddData = (Button)findViewById(R.id.button_add);
    btnviewAll = (Button)findViewById(R.id.button_viewAll);
    btnviewUpdate= (Button)findViewById(R.id.button_update);
    btnDelete= (Button)findViewById(R.id.button_delete);
    TimerValue.setText("00:00:00");
    txtSales.setText("0");
    txtFollow.setText("0");
    txtDone.setText("0");
    txtLeader.setText("00:00:00");
    txtTrain.setText("00:00:00");

    viewAll();
    AddData();
    UpdateData();
    CountSales();
    CountFollow();
    CountDone();
    TimeLeader();
    TimeTrain();
    StopTime();
}
public void CountSales() {
    SALES.setOnClickListener(
            new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    countSales++;
                    txtSales.setText(String.valueOf(countSales));
                }
            }
    );
}
public void CountFollow() {
    FOLLOW.setOnClickListener(
            new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    countFollow++;
                    txtFollow.setText(String.valueOf(countFollow));
                }
            }
    );
}
public void CountDone() {
    DONE.setOnClickListener(
            new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    countDone++;
                    txtDone.setText(String.valueOf(countDone));
                }
            }
    );
}
public void TimeLeader() {
    LEADER.setOnClickListener(
            new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    SALES.setClickable(false);
                    FOLLOW.setClickable(false);
                    DONE.setClickable(false);
                    LEADER.setClickable(false);
                    TRAIN.setClickable(false);
                    timeName = "leader";
                    mTimerTask = new TimerTask() {
                        public void run() {
                            handler.post(new Runnable() {
                                public void run() {
                                    nCounter++;
                                    TimerValue.setText("" + Utils.secToString(Integer.parseInt(String.valueOf(nCounter))));
                                    txtLeader.setText("" + Utils.secToString(Integer.parseInt(String.valueOf(nCounter))));
                                }
                            });
                        }};
                    t.schedule(mTimerTask, 200, 1000);  //
                }
                }
    );
}
public void TimeTrain() {
    TRAIN.setOnClickListener(
            new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    SALES.setClickable(false);
                    FOLLOW.setClickable(false);
                    DONE.setClickable(false);
                    LEADER.setClickable(false);
                    TRAIN.setClickable(false);
                    timeName = "train";
                    mTimerTask = new TimerTask() {
                        public void run() {
                            handler.post(new Runnable() {
                                public void run() {
                                    nCounter++;
                                    TimerValue.setText("" + Utils.secToString(Integer.parseInt(String.valueOf(nCounter))));
                                    txtTrain.setText("" + Utils.secToString(Integer.parseInt(String.valueOf(nCounter))));
                                }
                            });
                        }};
                    t.schedule(mTimerTask, 200, 1000);  //
                }
                }
    );
}
public void StopTime() {
    STOP.setOnClickListener(
            new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    SALES.setClickable(true);
                    FOLLOW.setClickable(true);
                    DONE.setClickable(true);
                    LEADER.setClickable(true);
                    TRAIN.setClickable(true);
                    if (mTimerTask != null) {
                        TimerValue.setText("" + Utils.secToString(Integer.parseInt(String.valueOf(nCounter))));
                        mTimerTask.cancel();
                        if (timeName == "leader") {
                            TimerValue.setText(Utils.secToString(0));
                            txtLeader.setText("" + Utils.secToString(Integer.parseInt(String.valueOf(nCounter))));
                        } else if (timeName == "train") {
                            TimerValue.setText(Utils.secToString(0));
                            txtTrain.setText("" + Utils.secToString(Integer.parseInt(String.valueOf(nCounter))));
                        }
                    }
                }
            }
    );
}
public void AddData() {
    btnAddData.setOnClickListener(
            new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    boolean isInserted = myDb.insertData(txtSales.getText().toString(),
                            txtFollow.getText().toString(),
                            txtDone.getText().toString(), txtLeader.getText().toString(), txtTrain.getText().toString() );
                    if(isInserted == true) {
                        Toast.makeText(MainActivity.this, "Data Inserted", Toast.LENGTH_LONG).show();
                        btnAddData.setVisibility(v.GONE);
                    }
                    else
                        Toast.makeText(MainActivity.this,"Data not Inserted",Toast.LENGTH_LONG).show();
                }
            }
    );
}
public void UpdateData() {
    btnviewUpdate.setOnClickListener(
            new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    boolean isUpdate = myDb.updateData(editTextId.getText().toString(),
                            txtSales.getText().toString(),
                            txtFollow.getText().toString(),
                            txtDone.getText().toString(), txtLeader.getText().toString(), txtTrain.getText().toString() );
                    if(isUpdate == true)
                        Toast.makeText(MainActivity.this,"Data Update",Toast.LENGTH_LONG).show();
                    else
                        Toast.makeText(MainActivity.this,"Data not Updated",Toast.LENGTH_LONG).show();
                }
            }
    );
}
public void viewAll() {
    REPORT.setOnClickListener(
            new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    Cursor res = myDb.getAllData();
                    if(res.getCount() == 0) {
                        // show message
                        showMessage("Error","Nothing found");
                        return;
                    }
                    StringBuffer buffer = new StringBuffer();
                    while (res.moveToNext()) {
                        buffer.append("Id :"+ res.getString(0)+"n");
                        buffer.append("Sales :"+ res.getString(1)+"n");
                        buffer.append("Follow :"+ res.getString(2)+"n");
                        buffer.append("Done :"+ res.getString(3)+"n");
                        buffer.append("Leader :"+ res.getString(4)+"n");
                        buffer.append("Train :"+ res.getString(5)+"n" );
                    }
                    // Show all data
                    showMessage("Data",buffer.toString());
                }
            }
    );
}
public void showMessage(String title,String Message){
    AlertDialog.Builder builder = new AlertDialog.Builder(this);
    builder.setCancelable(true);
    builder.setTitle(title);
    builder.setMessage(Message);
    builder.show();
}
}

activity_money 

<?xml version="1.0" encoding="utf-8"?>
<ScrollView 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="#000000">
<LinearLayout
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">
    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="horizontal">
    </LinearLayout>
    <TextView
        android:layout_width="match_parent"
        android:layout_height="match_parent" />
    <TextView
        android:id="@+id/tv_current_timeV2"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:gravity="center"
        android:text="00:00:00"
        android:textAppearance="?android:attr/textAppearanceLarge"
        android:textColor="@android:color/holo_green_light"
        android:textSize="38dp"
        android:textStyle="bold" />
    <TextView
        android:layout_width="match_parent"
        android:layout_height="match_parent" />

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="horizontal">
        <Button
            android:id="@+id/btnSales"
            android:layout_width="168dp"
            android:layout_height="match_parent"
            android:layout_marginLeft="100dp"
            android:onClick="onClick"
            android:text="SALES"  />
        <TextView
            android:id="@+id/textSales"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:text="0"
            android:textStyle="bold"
            android:textColor="@color/colorWhite"
            android:gravity="center"/>
    </LinearLayout>

    <TextView
        android:layout_width="match_parent"
        android:layout_height="match_parent" />
    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="horizontal">
        <Button
            android:id="@+id/btnFollow"
            android:layout_width="168dp"
            android:layout_height="match_parent"
            android:layout_marginLeft="100dp"
            android:onClick="onClick"
            android:text="FOLLOW"
            />
        <TextView
            android:id="@+id/textFollow"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:text="0"
            android:textStyle="bold"
            android:textColor="@color/colorWhite"
            android:gravity="center"/>

    </LinearLayout>
    <TextView
        android:layout_width="match_parent"
        android:layout_height="match_parent" />
    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="horizontal">
        <Button
            android:id="@+id/btnDone"
            android:layout_width="168dp"
            android:layout_height="match_parent"
            android:onClick="onClick"
            android:layout_marginLeft="100dp"
            android:text="DONE" />
        <TextView
            android:id="@+id/textDone"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:text="0"
            android:textStyle="bold"
            android:textColor="@color/colorWhite"
            android:gravity="center"/>
    </LinearLayout>
    <TextView
        android:layout_width="match_parent"
        android:layout_height="match_parent" />
    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="horizontal">
        <Button
            android:id="@+id/btnLeader"
            android:layout_width="168dp"
            android:layout_height="match_parent"
            android:layout_marginLeft="100dp"
            android:onClick="onClick"
            android:text="LEADER" />
        <TextView
            android:id="@+id/leaderTime"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:text="00:00:00"
            android:textStyle="bold"
            android:textColor="@color/colorWhite"
            android:gravity="center"/>
    </LinearLayout>
    <TextView
        android:layout_width="match_parent"
        android:layout_height="match_parent" />
    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="horizontal">
        <Button
            android:id="@+id/btnTrain"
            android:layout_width="168dp"
            android:layout_height="match_parent"
            android:onClick="onClick"
            android:layout_marginLeft="100dp"
            android:text="TRAIN" />
        <TextView
            android:id="@+id/trainTime"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:text="00:00:00"
            android:textStyle="bold"
            android:textColor="@color/colorWhite"
            android:gravity="center"/>
    </LinearLayout>
    <TextView
        android:layout_width="match_parent"
        android:layout_height="match_parent" />
    <Button
        android:id="@+id/btnStop"
        android:layout_width="168dp"
        android:layout_height="match_parent"
        android:layout_marginLeft="100dp"
        android:onClick="onClick"
        android:text="STOP"  />
    <TextView
        android:layout_width="match_parent"
        android:layout_height="match_parent" />
    <TextView
        android:layout_width="match_parent"
        android:layout_height="match_parent" />
    <TextView
        android:layout_width="match_parent"
        android:layout_height="match_parent" />
    <Button
        android:id="@+id/button_details"
        android:layout_width="168dp"
        android:layout_height="match_parent"
        android:layout_marginLeft="5dp"
        android:text="REPORT"
        android:textColor="@color/colorBlack"
        android:onClick="onClick"
        android:textStyle="bold"/>
    <Button
        android:id="@+id/button_add"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true"
        android:layout_below="@+id/editText_Marks"
        android:layout_marginTop="76dp"
        android:text="Add Data" />
    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Update"
        android:id="@+id/button_update"
        android:layout_below="@+id/button_add"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true" />
</LinearLayout>
</ScrollView>

错误日志

eror log

好的，所以您的错误原因是因为此行

editTextId = (EditText)findViewById(R.id.editText_id);

由于您的activity_money.xml布局中没有EditText，并且您正在尝试获取其参考，因此您获得了null参考。

首先将其添加到xml中或从Java文件中删除edittext行。

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