这是LOGIN活动。当我运行该应用程序。一切正常，启动画面和登录界面工作正常，但是当我在editText＆amp;中输入输入时按验证按钮，应用程序崩溃并提示我重新启动应用程序。
public class Login extends AppCompatActivity {
EditText cnic1;
EditText fcnic1;
EditText bill1;
ImageButton verify1;
String cc;
String fc;
String bl;
HashMap<String, String> user;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
requestWindowFeature(Window.FEATURE_NO_TITLE);
this.getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN);
setContentView(R.layout.activity_login);
cnic1 = (EditText) findViewById(R.id.cnic);
fcnic1 = (EditText) findViewById(R.id.fcnic);
bill1 = (EditText) findViewById(R.id.bill);
verify1 = (ImageButton) findViewById(R.id.verify);
Database db = new Database(this);
user = db.getUserDetails();
}
//Function for verification button
public void verification(View obj) {
if (cnic1.getText().toString().isEmpty() && fcnic1.getText().toString().isEmpty() && bill1.getText().toString().isEmpty()) {
Toast.makeText(this, "InComplete Credentials", Toast.LENGTH_SHORT).show();
} else {
String c = user.get("CNIC");
String f= user.get("FCNIC");
String s = user.get("Serial");
cc = cnic1.getText().toString();
fc = fcnic1.getText().toString();
bl = bill1.getText().toString();
if (c.equals(cc) && f.equals(fc) && s.equals(bl)) {
Intent z = new Intent(Login.this, Home.class);
startActivity(z);
} else {
Toast.makeText(this, "Wrong Credentials", Toast.LENGTH_SHORT).show();
}
}
}
}
这是数据库类。我添加了你给我的代码。我不知道问题是在数据库还是登录中。因为这是我第一次尝试为我的应用程序创建数据库。
public class Database extends SQLiteOpenHelper {
public Database(Context context) {
super(context, "DB.db", null, 1);
SQLiteDatabase db=this.getWritableDatabase();
}
//Creating table here
@Override
public void onCreate(SQLiteDatabase db) {
db.execSQL("Create Table Data (CNIC INTEGER Primary Key, FCNIC INTEGER, Serial INTEGER)");
}
//Adding upgrade code here
@Override
public void onUpgrade(SQLiteDatabase db, int i, int i1) {
db.execSQL("DROP TABLE IF EXISTS Data");
onCreate(db);
}
//This is the code that i have no idea of because i am reading Hashmap first time
public HashMap<String, String> getUserDetails() {
HashMap<String, String> user = new HashMap<String, String>();
String selectQuery = "SELECT * FROM Data";
SQLiteDatabase db = this.getReadableDatabase();
Cursor cursor = db.rawQuery(selectQuery, null);
// Move to first row
cursor.moveToFirst();
if (cursor.getCount() > 0) {
user.put("CNIC", cursor.getString(1));
user.put("FCNIC", cursor.getString(2));
user.put("Serial", cursor.getString(3));
}
cursor.close();
db.close();
// return user
Log.d("Log", "Fetching user from Sqlite: " + user.toString());
return user;
}
}
---
<!-- language: lang-none -->
02-13 00:03:51.624 28891-28891/com.pbrigade.www.pakgeneralelections E/BoostFramework: BoostFramework() : Exception_1 = java.lang.ClassNotFoundException: Didn't find class "com.qualcomm.qti.Performance" on path: DexPathList[[],nativeLibraryDirectories=[/system/lib64, /vendor/lib64]]
02-13 00:04:04.391 28891-28891/com.pbrigade.www.pakgeneralelections E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.pbrigade.www.pakgeneralelections, PID: 28891
java.lang.NullPointerException: Attempt to invoke virtual method 'boolean java.lang.String.equals(java.lang.Object)' on a null object reference
at com.pbrigade.www.pakgeneralelections.Login.verification(Login.java:93)
at com.pbrigade.www.pakgeneralelections.Login$1.onClick(Login.java:57)
at android.view.View.performClick(View.java:6205)
at android.view.View$PerformClick.run(View.java:23653)
at android.os.Handler.handleCallback(Handler.java:751)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:154)
at android.app.ActivityThread.main(ActivityThread.java:6682)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1520)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1410)
答案 0 :(得分：0)
activityMain
public class MainActivity extends AppCompatActivity {
EditText cnic1;
EditText fcnic1;
EditText bill1;
ImageButton verify1;
boolean isUserFound;
Database db;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
requestWindowFeature(Window.FEATURE_NO_TITLE);
this.getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN);
setContentView(R.layout.activity_main);
cnic1 = (EditText) findViewById(R.id.cnic);
fcnic1 = (EditText) findViewById(R.id.fcnic);
bill1 = (EditText) findViewById(R.id.bill);
verify1 = (ImageButton) findViewById(R.id.verify);
db = new Database(this);
//you forget onclick method
verify1.setOnClickListener(new View.OnClickListener()
{
@Override
public void onClick(View v)
{
verification();
}
});
}
//Function for verification button
public void verification()
{
if (cnic1.getText().toString().isEmpty() || fcnic1.getText().toString().isEmpty() || bill1.getText().toString().isEmpty()) {
Toast.makeText(this, "Empty Credentials", Toast.LENGTH_SHORT).show();
return;
}
else
{
isUserFound = db.getUserDetails(cnic1.getText().toString(),fcnic1.getText().toString(),bill1.getText().toString());
if(isUserFound)
{
Intent z = new Intent(MainActivity.this,hhActivity.class);
startActivity(z);
}
else
{
Toast.makeText(this, "Wrong Credentials", Toast.LENGTH_SHORT).show();
}
}
}
}
DB
public class Database extends SQLiteOpenHelper {
public Database(Context context) {
super(context, "DB.db", null, 1);
SQLiteDatabase db=this.getWritableDatabase();
}
//Creating table here
@Override
public void onCreate(SQLiteDatabase db) {
db.execSQL("Create Table Data (CNIC INTEGER Primary Key,FCNIC TEXT, Serial TEXT)");
}
//Adding upgrade code here
@Override
public void onUpgrade(SQLiteDatabase db, int i, int i1) {
db.execSQL("DROP TABLE IF EXISTS Data");
onCreate(db);
}
//This is the code that i have no idea of because i am reading Hashmap first time
public boolean getUserDetails(String cnic1, String fcn1, String serial)
{
String selectQuery = "SELECT * FROM Data where CNIC = '"+cnic1+"' and FCNIC = '"+fcn1+"' and Serial = '"+serial+"' ";
SQLiteDatabase db = this.getReadableDatabase();
Cursor cursor = db.rawQuery(selectQuery, null);
// Move to first row
cursor.moveToFirst();
Log.d("Log", "Fetching user from Sqlite: " + cursor.getCount());
if (cursor.getCount() > 0)
{
cursor.close();
db.close();
return true;
}
else
{
cursor.close();
db.close();
return false;
}
}
}