public class Student extends AppCompatActivity {

EditText editText6;
CheckBox checkBox2;
public Button button18;
DatabaseHelper helper = new DatabaseHelper(this);



@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_student);

    Button button8 = (Button)findViewById(R.id.button8);
    button8.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            if(v.getId() == R.id.button8){
                EditText a = (EditText)findViewById(R.id.editText7);
                String str = a.getText().toString();
                EditText b = (EditText)findViewById(R.id.editText6);
                String pass = b.getText().toString();


                String password = helper.searchPass(str);
                if (pass.equals(password))
                {
                    Intent us = new Intent(Student.this , Home.class);
                    startActivity(us);
                }
                else
                {
                    Toast temp = Toast.makeText(Student.this , "Username and password don't match" , Toast.LENGTH_SHORT);
                    temp.show();

                }
            }
        }
    });





    editText6 = (EditText) findViewById(R.id.editText6);
    checkBox2 = (CheckBox) findViewById(R.id.checkBox2);

    checkBox2.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
        @Override
        public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {

            if (! isChecked) {
                editText6.setTransformationMethod(PasswordTransformationMethod.getInstance());
            }else
            {
                editText6.setTransformationMethod(HideReturnsTransformationMethod.getInstance());
            }
        }
    });

    button18 = (Button) findViewById(R.id.button18);
    button18.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {

            Intent cut = new Intent(Student.this, Register.class);
            startActivity(cut);
        }
    });


}

@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_student, 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);
}

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent"
android:layout_height="match_parent" android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
android:paddingBottom="@dimen/activity_vertical_margin"
android:background="@drawable/background"
tools:context="com.example.username.mp.Student">


<TextView
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:textAppearance="?android:attr/textAppearanceLarge"
    android:text="ITSM Application"
    android:textSize="40dp"
    android:id="@+id/textView9"
    android:layout_alignParentTop="true"
    android:layout_centerHorizontal="true" />

<TextView
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:textAppearance="?android:attr/textAppearanceLarge"
    android:text="Login"
    android:id="@+id/textView10"
    android:layout_below="@+id/textView9"
    android:layout_centerHorizontal="true"
    android:layout_marginTop="46dp" />

<TextView
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:textAppearance="?android:attr/textAppearanceLarge"
    android:text="Username:"
    android:id="@+id/textView16"
    android:layout_below="@+id/textView10"
    android:layout_alignParentLeft="true"
    android:layout_alignParentStart="true"
    android:layout_marginTop="89dp" />

<TextView
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:textAppearance="?android:attr/textAppearanceLarge"
    android:text="Password:"
    android:id="@+id/textView17"
    android:layout_alignTop="@+id/editText6"
    android:layout_alignParentLeft="true"
    android:layout_alignParentStart="true" />

<EditText
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:inputType="textPassword"
    android:ems="10"
    android:id="@+id/editText6"
    android:layout_below="@+id/textView16"
    android:layout_alignParentRight="true"
    android:layout_alignParentEnd="true"
    android:layout_marginTop="68dp" />

<EditText
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:id="@+id/editText7"
    android:layout_alignBottom="@+id/textView16"
    android:layout_alignLeft="@+id/editText6"
    android:layout_alignStart="@+id/editText6"
    android:layout_alignRight="@+id/editText6"
    android:layout_alignEnd="@+id/editText6" />

<Button
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="SIGN IN"
    android:id="@+id/button8"
    android:background="#E0E0E0"
    android:layout_alignParentBottom="true"
    android:layout_alignLeft="@+id/textView9"
    android:layout_alignStart="@+id/textView9" />

<CheckBox
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="Show Password"
    android:id="@+id/checkBox2"
    android:checked="false"
    android:layout_below="@+id/editText6"
    android:layout_alignLeft="@+id/editText6"
    android:layout_alignStart="@+id/editText6" />

<Button
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="SIGN UP"
    android:id="@+id/button18"
    android:background="#E0E0E0"
    android:layout_alignParentBottom="true"
    android:layout_alignRight="@+id/editText6"
    android:layout_alignEnd="@+id/editText6" />

public class DatabaseHelper extends SQLiteOpenHelper {
private static final int DATABASE_VERSION = 1;
public static final String DATABASE_NAME = "contacts.db";
public static final String TABLE_NAME = "contacts";
public static final String COLUMN_ID = "id";
public static final String COL_1 = "Name";
public static final String COL_2 = "Pass";
public static final String COL_3 = "email";
SQLiteDatabase db;

private static final String TABLE_CREATE = "create table contacts (id integer primary key not null , " +
        "name not null, pass text not null, email text not null);";


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

@Override
public void onCreate(SQLiteDatabase db) {
    db.execSQL(TABLE_CREATE);
    this.db = db;

}

public void insertContact(Contact c)
{
    db = this.getWritableDatabase();
    ContentValues values = new ContentValues();

    String query = "select * from contacts";
    Cursor cursor = db.rawQuery(query , null);
    int count = cursor.getCount();

    values.put(COLUMN_ID , count);
    values.put(COL_1, c.getName());
    values.put(COL_2, c.getPass());
    values.put(COL_3, c.getEmail());

    db.insert(TABLE_NAME, null, values);
    db.close();
}

public String searchPass(String name)
{
    db = this.getReadableDatabase();
    String query = "select name, pass from" + TABLE_NAME;
    Cursor cursor = db.rawQuery(query , null);
    String a, b;
    b = "not found";

    if(cursor.moveToFirst())
    {
        do {
            a = cursor.getString(0);


            if(a.equals(name))
            {
                b = cursor.getString(1);
                break;
            }
        }
        while (cursor.moveToNext());
    }

    return b;

}




@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
    String query = "DROP TABLE IF EXISTS" + TABLE_NAME;
    db.execSQL(query);
    this.onCreate(db);

}

<?xml version="1.0" encoding="utf-8"?>

<uses-permission android:name="android.permission.INTERNET" />

<application
    android:allowBackup="true"
    android:icon="@mipmap/ic_launcher"
    android:label="@string/app_name"
    android:theme="@style/AppTheme" >
    <activity
        android:name=".MainActivity"
        android:label="@string/app_name" >
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />

            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
    </activity>
    <activity
        android:name=".Login"
        android:label="@string/title_activity_login" >
    </activity>
    <activity
        android:name=".Option"
        android:label="@string/title_activity_option" >
    </activity>
    <activity
        android:name=".Detail"
        android:label="@string/title_activity_detail" >
    </activity>
    <activity
        android:name=".End"
        android:label="@string/title_activity_end" >
    </activity>
    <activity
        android:name=".Feedback"
        android:label="@string/title_activity_feedback" >
    </activity>
    <activity
        android:name=".Student"
        android:label="@string/title_activity_student" >
    </activity>
    <activity
        android:name=".Incident"
        android:label="@string/title_activity_incident" >
    </activity>
    <activity
        android:name=".Help"
        android:label="@string/title_activity_help" >
    </activity>
    <activity
        android:name=".Wifi"
        android:label="@string/title_activity_wifi" >
    </activity>
    <activity
        android:name=".Basic"
        android:label="@string/title_activity_basic" >
    </activity>
    <activity
        android:name=".Home"
        android:label="@string/title_activity_home" >
    </activity>
    <activity
        android:name=".Guide"
        android:label="@string/title_activity_guide" >
    </activity>
    <activity
        android:name=".VPN"
        android:label="@string/title_activity_vpn" >
    </activity>
    <activity
        android:name=".VDI"
        android:label="@string/title_activity_vdi" >
    </activity>
    <activity
        android:name=".Location"
        android:label="@string/title_activity_location" >
    </activity>
    <activity
        android:name=".Phone"
        android:label="@string/title_activity_phone" >
    </activity>
    <activity
        android:name=".config"
        android:label="@string/title_activity_config" >
    </activity>
    <activity
        android:name=".Script"
        android:label="@string/title_activity_script" >
    </activity>

    <meta-data
        android:name="com.facebook.sdk.ApplicationId"
        android:value="@string/facebook_app_id" />

    <activity
        android:name="com.facebook.FacebookActivity"
        android:label="@string/app_name"
        android:screenOrientation="portrait" />

    <provider
        android:name="com.facebook.FacebookContentProvider"
        android:authorities="com.facebook.app.FacebookContentProvider"
        android:exported="true" />

    <activity
        android:name=".Register"
        android:label="@string/title_activity_register" >
    </activity>

</application>