基本上,当我运行应用程序时,它说,它无法添加,num1input和num2input到数据库,因为
有错误entry.createEntry(number_one, number_two, answer);
这是我的MainActivity代码:我也拿出了答案,因为它出现了一个错误,我认为这是因为进行计算的按钮没有给出相同的输出,而且#&# 39;基本上是从XML重命名TextView。
public class MainActivity extends Activity implements OnClickListener {
Button sqlUpdate, sqlView;
EditText sqlNumber1, sqlNumber2, sqlAnswer;
@Override
protected void onCreate(Bundle savedInstanceState){
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
sqlUpdate = (Button) findViewById(R.id.bSQLUpdate);
sqlNumber1 = (EditText)findViewById(R.id.num1input);
sqlNumber2 = (EditText)findViewById(R.id.num2input);
sqlAnswer = (EditText)findViewById(R.id.ans1);
sqlView = (Button) findViewById(R.id.bSQLopenView);
sqlView.setOnClickListener(this);
sqlUpdate.setOnClickListener(this);
}
public void onClick(View arg0) {
switch (arg0.getId()){
case R.id.bSQLUpdate:
boolean didItWork = true;
try{
String number_one = sqlNumber1.getText().toString();
String number_two = sqlNumber2.getText().toString();
String answer = sqlAnswer.getText().toString();
DBA entry = new DBA(MainActivity.this);
entry.open();
entry.createEntry(number_one, number_two);
entry.close();
} catch (Exception e) {
didItWork = false;
String error = e.toString();
Dialog d = new Dialog(this);
d.setTitle("Damn!");
TextView tv = new TextView(this);
tv.setText(error);
d.setContentView(tv);
d.show();
}finally{
if (didItWork){
Dialog d = new Dialog(this);
d.setTitle("It Worked");
TextView tv = new TextView(this);
tv.setText("Success!");
d.setContentView(tv);
d.show();
}
}
break;
case R.id.bSQLopenView:
Intent i = new Intent("com.cmpcione.calculator.SQLVIEW");
startActivity(i);
break;
}
}
public void sum(View v) {
EditText number1input = (EditText)findViewById(R.id.num1input);
EditText number2input = (EditText)findViewById(R.id.num2input);
Integer num1=Integer.parseInt(number1input.getText().toString()),num2=Integer.parseInt(number2input.getText().toString());
Integer ans1=num1+num2;
TextView answer=(TextView)findViewById(R.id.ans1);
answer.setText(ans1.toString());
}
DBA类的代码:
public class DBA {
public static final String KEY_ROWID = "_id";
public static final String KEY_NUMBER1 = "num1input";
public static final String KEY_NUMBER2 = "num2input";
public static final String KEY_ANSWER = "ans1";
private static final String DATABASE_NAME = "CalculationsDB";
private static final String DATABASE_TABLE = "Calculation_table";
private static final int DATABASE_VERSION = 2;
private DbHelper ourHelper;
private final Context ourContext;
private SQLiteDatabase ourDatabase;
private static class DbHelper extends SQLiteOpenHelper{
public DbHelper(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
//creates table and rows
db.execSQL("CREATE TABLE " + DATABASE_TABLE + " (" +
KEY_ROWID + " INTEGER PRIMARY KEY, " +
KEY_NUMBER1 + " TEXT NOT NULL, " +
KEY_NUMBER2 + " TEXT NOT NULL, " +
KEY_ANSWER + " TEXT NOT NULL);"
);
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
// TODO Auto-generated method stub
db.execSQL("DROP TABLE IF EXISTS " + DATABASE_TABLE);
onCreate(db);
}
}
public DBA(Context c){
ourContext = c;
}
public DBA open() {
ourHelper = new DbHelper(ourContext);
ourDatabase = ourHelper.getWritableDatabase();
return this;
}
public void close() {
ourHelper.close();
}
public long createEntry(String number_one, String number_two) {
// TODO Auto-generated method stub
ContentValues cv = new ContentValues();
cv.put(KEY_NUMBER1, number_one);
cv.put(KEY_NUMBER2, number_two);
cv.put(KEY_ANSWER, answer);
return ourDatabase.insert(DATABASE_TABLE, null, cv);
}
public String getData() {
// TODO Auto-generated method stub
String[] columns = new String[]{KEY_ROWID, KEY_NUMBER1, KEY_NUMBER2};
//using the cursor to read from database
Cursor c = ourDatabase.query(DATABASE_TABLE, columns, null, null, null, null, null);
String result = " ";
int iRow = c.getColumnIndex(KEY_ROWID);
int iNumber1 = c.getColumnIndex(KEY_NUMBER1);
int iNumber2 = c.getColumnIndex(KEY_NUMBER2);
int iAnswer = c.getColumnIndex(KEY_ANSWER);
for (c.moveToFirst(); !c.isAfterLast(); c.moveToNext()) {
//it gets the string of our index then it gets the first number and then the last
result = result + c.getString(iRow) + " " + c.getString(iNumber1) + " " + c.getString(iNumber2) + "\n";
}
return null;
}
} logcat的完整列表:它从无法将数字插入数据库开始:
04-11 17:57:48.177: E/AndroidRuntime(278): FATAL EXCEPTION: main
04-11 17:57:48.177: E/AndroidRuntime(278): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.cmpcione.calculator/com.cmpcione.calculator.MainActivity}: java.lang.ClassCastException: android.widget.TextView
04-11 17:57:48.177: E/AndroidRuntime(278): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2663)
04-11 17:57:48.177: E/AndroidRuntime(278): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2679)
04-11 17:57:48.177: E/AndroidRuntime(278): at android.app.ActivityThread.access$2300(ActivityThread.java:125)
04-11 17:57:48.177: E/AndroidRuntime(278): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2033)
04-11 17:57:48.177: E/AndroidRuntime(278): at android.os.Handler.dispatchMessage(Handler.java:99)
04-11 17:57:48.177: E/AndroidRuntime(278): at android.os.Looper.loop(Looper.java:123)
04-11 17:57:48.177: E/AndroidRuntime(278): at android.app.ActivityThread.main(ActivityThread.java:4627)
04-11 17:57:48.177: E/AndroidRuntime(278): at java.lang.reflect.Method.invokeNative(Native Method)
04-11 17:57:48.177: E/AndroidRuntime(278): at java.lang.reflect.Method.invoke(Method.java:521)
04-11 17:57:48.177: E/AndroidRuntime(278): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)
04-11 17:57:48.177: E/AndroidRuntime(278): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)
04-11 17:57:48.177: E/AndroidRuntime(278): at dalvik.system.NativeStart.main(Native Method)
04-11 17:57:48.177: E/AndroidRuntime(278): Caused by: java.lang.ClassCastException: android.widget.TextView
04-11 17:57:48.177: E/AndroidRuntime(278): at com.cmpcione.calculator.MainActivity.onCreate(MainActivity.java:27)
04-11 17:57:48.177: E/AndroidRuntime(278): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
04-11 17:57:48.177: E/AndroidRuntime(278): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2627)
答案 0 :(得分:6)
是因为您的表名为Calculations
而不是Calculation_Table
?
如果您编辑了表定义,请确保增加数据库版本,使其进入onUpgrade
方法并重新创建数据库。
您看到的下一个问题constraint failed
是由answer
列未插入任何值引起的。定义说它是not null
。
以下是您需要做的事情:
public long createEntry(String number_one, String number_two) {
// TODO Auto-generated method stub
ContentValues cv = new ContentValues();
cv.put(KEY_NUMBER1, number_one);
cv.put(KEY_NUMBER2, number_two);
// the answer needs to be added to cv, uncomment the line and figure out the answer.
int answer = Integer.parseInt(number_one) + Integer.parseInt(number_two);
cv.put(KEY_ANSWER, answer);
return ourDatabase.insert(DATABASE_TABLE, null, cv);
}