这是我的主要活动..所有我想要发生的是当用户点击登录用户将被定向到活动用户所属..如果用户名等于admin用户将指向管理员模块，如果用户不是等于管理员用户将直接到客户端模块..但每次我输入用户名和密码fiel后点击登录...我的模拟器总是停止..
public class MainActivity extends ActionBarActivity {
Button btnLogin;
Button btnRegister;
EditText pass,un;
User userdb;
public String user_name;
public String pass_word;
private DBHelper dbHelper;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
un = (EditText) findViewById(R.id.eTlogUser);
pass = (EditText) findViewById(R.id.eTlogPass);
btnLogin = (Button)findViewById(R.id.btnlogin);
btnRegister = (Button) findViewById(R.id.btnregister);
btnLogin.setOnClickListener(new View.OnClickListener(){
/* @Override
public void onClick(View v) {
startActivity(new Intent(MainActivity.this,AdminModule.class));
}
}); */
@Override
public void onClick(View v) {
if(v.getId() == R.id.btnlogin) {
// dbHelper.onOpen(User.TABLE);
Cursor cursor = dbHelper.getReadableDatabase().rawQuery("SELECT * FROM " + User.TABLE, null);
cursor.moveToFirst();
{
System.out.println("compiler was here!");
if (cursor.getCount() == 0) {
Toast.makeText(getApplicationContext(), "The table " + User.TABLE + " is empty", Toast.LENGTH_LONG).show();
} else if (cursor.getCount() >= 1) {
do {
if ((cursor.getString(9) == un.toString()) && (cursor.getString(10) == pass.toString())) {
Toast.makeText(getApplicationContext(), cursor.getString(1), Toast.LENGTH_LONG).show();
// Intent goToNextActivity = new Intent(getApplicationContext(), AdminModule.class);
if (cursor.getString(1) == "admin") {
startActivity(new Intent(MainActivity.this, AdminModule.class));
} else {
startActivity(new Intent(MainActivity.this, ClientModule.class));
}
// startActivity(goToNextActivity);
//startActivity(new Intent(MainActivity.this, AdminModule.class));
} else {
Toast.makeText(getApplicationContext(), "Wrong username/password", Toast.LENGTH_LONG).show();
}
} while (cursor.moveToNext());
}
}
}
}
});
btnRegister.setOnClickListener(new View.OnClickListener(){
@Override
public void onClick(View v) {
startActivity(new Intent(MainActivity.this,UserDetail.class));
}
});
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.menu_main, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
//noinspection SimplifiableIfStatement
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
}
这不是我在logcat中的错误...
01-29 00:28:08.148 887-887/com.ampo.mobileampo.ampo E/AndroidRuntime﹕ FATAL EXCEPTION: main
Process: com.ampo.mobileampo.ampo, PID: 887
java.lang.NullPointerException
at com.ampo.mobileampo.ampo.MainActivity$1.onClick(MainActivity.java:53)
at android.view.View.performClick(View.java:4438)
at android.view.View$PerformClick.run(View.java:18422)
at android.os.Handler.handleCallback(Handler.java:733)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:136)
at android.app.ActivityThread.main(ActivityThread.java:5017)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
at dalvik.system.NativeStart.main(Native Method)
这是我的用户
中的crud操作代码 public class UserDetail extends Activity implements View.OnClickListener {
Button ubtnsave, ubtnclose, ubtndelete;
EditText etutype, etusex,etusername;
EditText etucompany, etumail, etucont, etuadd;
EditText etloguserName, etlogpass, etlogconfirm;
private String pasword,pasword2;
private int _User_Id=0;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_user_detail);
ubtnsave = (Button) findViewById(R.id.ubtnsave);
ubtnclose = (Button) findViewById(R.id.ubtnclose);
ubtndelete = (Button) findViewById(R.id.ubtndelete);
etusername= (EditText) findViewById(R.id.eTuname);
etutype = (EditText) findViewById(R.id.eTutype);
etusex = (EditText) findViewById(R.id.eTsex);
etucompany = (EditText) findViewById(R.id.eTucompany);
etumail = (EditText) findViewById(R.id.eTuemail);
etucont = (EditText) findViewById(R.id.eTucont);
etuadd = (EditText) findViewById(R.id.eTuadd);
etloguserName = (EditText) findViewById(R.id.eTloguserName);
etlogpass = (EditText) findViewById(R.id.eTlogPass);
etlogconfirm = (EditText) findViewById(R.id.eTconfirmPass);
_User_Id=0;
Intent intentu = getIntent();
_User_Id = intentu.getIntExtra("user_Id", 0);
UserCrud uCrud = new UserCrud(this);
User user = new User();
user = uCrud.getUserById(_User_Id);
etusername.setText(user.username);
etutype.setText(user.usertype);
etusex.setText(user.sex);
etucompany.setText(user.usercompany);
etumail.setText(user.usermail);
etucont.setText(String.valueOf(user.usercontact));
etuadd.setText(user.useradd);
etloguserName.setText(user.loguser);
etlogpass.setText(user.logpass);
etlogconfirm.setText(user.logconfirmm);
}
// stopped here 3:15 am
@Override
public void onClick(View v) {
if (v == findViewById(R.id.ubtnsave)){
Toast.makeText(this, pasword, Toast.LENGTH_LONG).show();
Toast.makeText(this, pasword2, Toast.LENGTH_LONG).show();
UserCrud uCrud = new UserCrud(this);
User user = new User();
user.privl = "Client";
user.username=etusername.getText().toString();
user.usertype=etutype.getText().toString();
user.sex=etusex.getText().toString();
user.usercompany=etucompany.getText().toString();
user.usermail=etumail.getText().toString();
user.usercontact=etucont.getText().toString();
user.useradd=etuadd.getText().toString();
user.loguser=etloguserName.getText().toString();
user.logpass=etlogpass.getText().toString();
user.logconfirmm=etlogconfirm.getText().toString();
pasword = etlogpass.getText().toString();
pasword2 = etlogconfirm.getText().toString();
if (_User_Id==0){
if(pasword.equals(pasword2))
{ _User_Id = uCrud.insert(user);
Toast.makeText(this, "User Saved", Toast.LENGTH_SHORT).show();
}
else {
Toast.makeText(this, "Password doesn't Match" , Toast.LENGTH_LONG).show();
}
}else{
uCrud.update(user);
Toast.makeText(this, "User Updated", Toast.LENGTH_SHORT).show();
}
}else if (v == findViewById(R.id.ubtndelete)){
UserCrud uCrud = new UserCrud(this);
uCrud.delete(_User_Id);
Toast.makeText(this, "User Deleted", Toast.LENGTH_SHORT).show();
finish();
}else if (v == findViewById(R.id.ubtnclose)){
finish();
}
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.menu_user_detail, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
//noinspection SimplifiableIfStatement
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
}
我不知道为什么我点击登录按钮后我的模拟器总是停止？
答案 0 :(得分：0)
在主活动中，您未初始化以下dbhelper类对象
private DBHelper dbHelper;
初始化上面的Object Like：
in OnCreate()
dbHelper=new DBHelper(this);
答案 1 :(得分：0)
在活动的onCreate方法中初始化dbHelper对象
dbHelper=new DBHelper(MainActivity.this);
答案 2 :(得分：0)
初始化dbHelper
dbHelper = new DBHelper(MainActivity.this);
还要在这里添加，确保字符串比较以正确的方式完成..
How do I compare strings in Java?
以上链接可以帮助您。