Question

我想在编辑文本字段中输入日期，该日期应通过单击保存按钮存储在表格中。之后选择应该在第二页显示的数据怎么做。请帮助我。

这是我的代码

数据库Helper.java ：

public class DatabaseHelper extends SQLiteOpenHelper 
{
     public DatabaseHelper(Context  context) {
    super(context, DATABASE_NAME, null, DATABASE_VERSION);
}

// Logcat tag
private static final String LOG = "DatabaseHelper";

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

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

// Table Names

private static final String TABLE_FLUIDHISTORY = "fluidhistory";

//fluid history-column names
private static final String FLUIDCHANGE_ID = "fluidchageid";
private static final String FCVEHICLE_ID = "vehicalid";
private static final String FCFLUID_ID = "fluidid";
private static final String LAST_CHANGE = "lastchangedate";
private static final String NEXT_CHANGE = "nextchangedate";
private static final String LAST_CHANGEODO = "lastchangeodo";
private static final String NEXT_CHANGEODO = "nextchangeodo";

// Table Create Statements

//fluidchange table stament
private static final String CREATE_TABLE_FLUIDCHANGE = "CREATE TABLE " + TABLE_FLUIDHISTORY
                            + "(" + FLUIDCHANGE_ID + " INTEGER PRIMARY KEY," + FCVEHICLE_ID + " INTEGER"+ FCFLUID_ID + "INTEGER"  + "DATE" +NEXT_CHANGE +"DATE"+LAST_CHANGEODO +"INTEGER" + NEXT_CHANGEODO +"INTEGER" +");";        


            @Override
            public void onCreate(SQLiteDatabase db) {

                // creating required tables

                db.execSQL(CREATE_TABLE_FLUIDCHANGE);
            }

            @Override
            public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
                // on upgrade drop older tables

                db.execSQL("DROP TABLE IF EXISTS " + TABLE_FLUIDHISTORY);

                // create new tables
                onCreate(db);
            }
    enter code here

            public void addFluidhistory(Fluidhistory fluidhistory) {
                // TODO Auto-generated method stub


                SQLiteDatabase db = this.getWritableDatabase();
                ContentValues values = new ContentValues();

                values.put(LAST_CHANGE, fluidhistory.getLastchangedate()); // First Name
                values.put(NEXT_CHANGE, fluidhistory.getNextchangedate());
                values.put(LAST_CHANGEODO, fluidhistory.getLastchangeodo());
                values.put(NEXT_CHANGEODO, fluidhistory.getNextchangeodo());// Last Name
                // Inserting Row
                db.insert(TABLE_FLUIDHISTORY , null, values);
                // Closing database connection
                db.close(); 



            }

            public List<Fluidhistory> getFluidHistory() {
                // TODO Auto-generated method stub
                List<Fluidhistory> nameVoList = new ArrayList<Fluidhistory>();
                // Select All Query
                String selectQuery = "SELECT  * FROM " + TABLE_FLUIDHISTORY;
                SQLiteDatabase db1 = this.getWritableDatabase();
                Cursor cursor = db1.rawQuery(selectQuery, null);
                // looping through all rows and adding to list
                if (cursor.moveToFirst()) {
                    do {
                        Fluidhistory nameVO = new Fluidhistory();

                        nameVO.setLastchangedate(cursor.getString(0));
                        nameVO.setNextchangedate(cursor.getString(1));
                        nameVO.setLastchangeodo(cursor.getString(2));
                        nameVO.setNextchangeodo(cursor.getString(3));
                        // Adding NameVO to list
                        nameVoList.add(nameVO);                 
                        }
                    while (cursor.moveToNext());
                }
                // return NameVO list
                return nameVoList;

            }



}
main activity class:

她是主要的活动类代码，所以请参考此代码并帮助我如何更改它。

import android.os.Bundle;
import android.support.v7.app.ActionBarActivity;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;

public class MainActivity extends ActionBarActivity {
private  EditText edt1,edt2,edt3,edt4;
private DatabaseHelper handler;
    @SuppressWarnings("unused")
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.first_screen);
       // StringBuffer details=new StringBuffer();
        TextView names=(TextView)findViewById(R.id.textview1);
        final  EditText edt1=(EditText)findViewById(R.id.editText1);
        final EditText edt2=(EditText)findViewById(R.id.editText2);
        final EditText edt3=(EditText)findViewById(R.id.editText3);
        final EditText edt4=(EditText)findViewById(R.id.editText4);
        Button btn=(Button)findViewById(R.id.save);

        final DatabaseHelper handler=new DatabaseHelper(this);

        btn.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View v) {
                // TODO Auto-generated method stub
                handler.addFluidhistory(new Fluidhistory(edt1.getText().toString(),edt2.getText().toString(),edt3.getText().toString(),edt4.getText().toString()));
            }
        });







    }



}

它不能为我工作。在输入值点击保存按钮后，应用程序将关闭。为什么我发生这样的事你能有人知道请帮助我。提前谢谢你。

更新logcat：

06-03 02:16:44.695: E/AndroidRuntime(1102): FATAL EXCEPTION: main 
06-03 02:16:44.695: E/AndroidRuntime(1102): Process: com.example.tejuraju, PID: 1102 
06-03 02:16:44.695: E/AndroidRuntime(1102): java.lang.NullPointerException 
06-03 02:16:44.695: E/AndroidRuntime(1102): at com.example.tejuraju.MainActivity.onClick(MainActivity.java:57) 
06-03 02:16:44.695: E/AndroidRuntime(1102): at android.view.View.performClick(View.java:4438) 
06-03 02:16:44.695: E/AndroidRuntime(1102): at android.view.View$PerformClick.run(View.java:18422) 
06-03 02:16:44.695: E/AndroidRuntime(1102): at android.os.Handler.handleCallback(Handler.java:733) 
06-03 02:16:44.695: E/AndroidRuntime(1102): at android.os.Handler.dispatchMessage(Handler.java:95) 
06-03 02:16:44.695: E/AndroidRuntime(1102): at android.os.Looper.loop(Looper.java:136) 
06-03 02:16:44.695: E/AndroidRuntime(1102): at android.app.ActivityThread.main(ActivityThread.java:5017) 
06-03 02:16:44.695: E/AndroidRuntime(1102): at java.lang.reflect.Method.invokeNative(Native Method) 
06-03 02:16:44.695: E/AndroidRuntime(1102): at java.lang.reflect.Method.invoke(Method.java:515) 
06-03 02:16:44.695: E/AndroidRuntime(1102): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779) 
06-03 02:16:44.695: E/AndroidRuntime(1102): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595) 
06-03 02:16:44.695: E/AndroidRuntime(1102): at dalvik.system.NativeStart.main(Native Method)

Answer 1

为了保存数据，有很多选择。

如果它只是一个日期值，您可以使用共享首选项。

参考： http://www.vogella.com/tutorials/AndroidFileBasedPersistence/article.html
如果它将成为下一个活动中只需要的临时值，那么您可以使用通过INTENT传递值。

参考： http://www.vogella.com/tutorials/AndroidIntent/article.html
如果要将值保存在DB（Advisable for multiple records / table structure）中，可以使用SQL Lite

<强>参考： http://www.androidhive.info/2011/11/android-sqlite-database-tutorial/

Answer 2

您已经为private DatabaseHelper handler;

声明了变量

所以在onCreate()上不需要再次声明它。只需初始化，

 handler=new DatabaseHelper(this);

您也不需要为EditText声明变量。他们必须

 edt1=(EditText)findViewById(R.id.editText1);
 edt2=(EditText)findViewById(R.id.editText2);
 edt3=(EditText)findViewById(R.id.editText3);
 edt4=(EditText)findViewById(R.id.editText4);

还必须检查所有UI的ID是否必须更正，并在first_screen.xml文件中。

在SQlite数据库中插入并选择

2 个答案: