Java

15-Mar-20 3:49

You're welcome. Maybe you will be answering questions in the future.

My First Java

MallardsReach12-Mar-20 10:07

12-Mar-20 10:07

Hi and thanks for looking,
Just started to learn Java and after reading various tutorials came up with this simple tables program.
My question, is it as it should be? I mean it works OK but is it coded correctly?

Java

import java.util.Scanner;  // Import the Scanner class
public class MyTables {
  public static void main(String[] args) {
	int secondNum, answerNum;
	
	Scanner sc = new Scanner(System.in);  // Create a Scanner object
    System.out.println("Type a number:");
    secondNum = sc.nextInt(); // Read user input	
	
	for (int firstNum = 1; firstNum <= 12; firstNum ++) { 
	answerNum = firstNum * secondNum;
    System.out.println(firstNum + " x " + secondNum + " = " + answerNum);
	  }
	}
}

Re: My First Java

Richard MacCutchan12-Mar-20 23:23

12-Mar-20 23:23

Looks OK and works, so that should be enough. You may like to use formatting on your output so all table entries are on the same column - currently the x and beyond is shifted right from 10 onwards.

Re: My First Java

MallardsReach13-Mar-20 2:59

books examples of precedures stored for sqlserver

13-Mar-20 2:59

Thanks for the reply and for the suggestion re formatting.

Member 147683149-Mar-20 21:20

Member 14768314

9-Mar-20 21:20

books examples of precedures stored for sqlserver

Re: books examples of precedures stored for sqlserver

Richard MacCutchan9-Mar-20 22:25

Re: books examples of precedures stored for sqlserver

9-Mar-20 22:25

Liquid nitrogen.

ZurdoDev12-Mar-20 11:03

ZurdoDev

12-Mar-20 11:03

Search on Amazon. There are tons of them.

Social Media - A platform that makes it easier for the crazies to find each other.

Everyone is born right handed. Only the strongest overcome it.
Fight for left-handed rights and hand equality.

PLEASE HELP JAVA

Member 147599401-Mar-20 14:19

Member 14759940

1-Mar-20 14:19

Question: Write a Java program for a 2-dice game. This game will roll the two dice together for 100 times. In each time, it will display the face values from both dice. The program will count how many times (out of these 100 attempts) did the two dice generate a total point of 10 or above, and display the result at the end. (10 pts) See the execution example above.
Requirements:
a) In this question, use the Random class and its object to simulate dice rolling. Make sure your dice will generate integer values in the range of 1 - 6.
b) You will need two counter variables. One is to count for how many attempts you have rolled the two dice – to control the loop. The other is to count how many times that your two dices gave a total point of 10 or above.
c) Use a WHILE loops in this program. DO NOT USE THE OTHER LOOP METHODS in this question.
d) Your class should be named TwoDiceGame, and your source code file should be named TwoDiceGame.java.
e) Programming styles are always required.

My code:
import java.util.Random;

public class TwoDiceGame {
public static void main(String[] args){

// Declare a counter variable to count the loop time
int count = 0;

int die1, die2;

for(int i=0;i<100;i++)

rNums = new Random(); // create a new object of Random class

int die1 = rNums.nextInt(6)+1;
int die2= rNums.nextInt(6)+1;

if(Die1 + Die2 >= 10);
count ++;

}

System.out.println ("Out of 100 rolls of the two dice, the total of both the dice greater than or equal to 10 was %d times");
}
{
}

Errors:

----jGRASP exec: javac -g TwoDiceGame.java
TwoDiceGame.java:32: error: <identifier> expected
    System.out.println ("Out of 100 rolls of the two dice, the total of both the dice greater than or equal to 10 was %d times");
                      ^
TwoDiceGame.java:32: error: illegal start of type
    System.out.println ("Out of 100 rolls of the two dice, the total of both the dice greater than or equal to 10 was %d times");
                        ^
TwoDiceGame.java:34: error: class, interface, or enum expected
       {
       ^
3 errors

 ----jGRASP wedge: exit code for process is 1.
 ----jGRASP: operation complete.

Can someone please help me revise this code? I have this due by tonight and have tried everything to fix it.

Richard MacCutchan1-Mar-20 21:36

1-Mar-20 21:36

The call to System.out.println is outside of the main method, which is incorrect. Using proper indentation helps to see such basic errors.
It should be

Java

import java.util.Random;

public class TwoDiceGame {
    public static void main(String[] args){
        // Declare a counter variable to count the loop time
        int count = 0;
        int die1, die2;
        
        for(int i=0;i<100;i++) { // on reflection the problem is this missing open brace        
            rNums = new Random(); // create a new object of Random class
            int die1 = rNums.nextInt(6)+1;  // you already declared die1 and die2 above
            int die2= rNums.nextInt(6)+1;
            if(Die1 + Die2 >= 10);  // you have mis-spelled the names of the two die variables
            count ++;
        } // this brace closes the for loop
    
        System.out.println ("Out of 100 rolls of the two dice, the total of both the dice greater than or equal to 10 was %d times");
    } // this is the correct closing of main
// { this open brace should not be here
} // this closes the class

Richard MacCutchan1-Mar-20 21:42

1-Mar-20 21:42

I also just noticed that the instructions tell you to use a "while" loop and not any other type.

Member 1477360615-Mar-20 10:11

Member 14773606

15-Mar-20 10:11

Try to use another loop...

Richard MacCutchan15-Mar-20 12:26

15-Mar-20 12:26

What?

MallardsReach13-Mar-20 3:12

13-Mar-20 3:12

Here's what I came up with not sating it's the correct way as I am only just starting with Java but it works.

Java

import java.util.Random;

public class TwoDiceGame {
    public static void main(String[] args){
        // Declare a counter variable to count the loop time
        int count = 0, total = 0;
        
        for(int i=0;i<100;i++){
           Random rNums = new Random(); // create a new object of Random class
            int rNums_die1 = rNums.nextInt(6)+1; 
            int rNums_die2 = rNums.nextInt(6)+1;
			
            if(rNums_die1 + rNums_die2 >= 10){
				total ++;
		         count ++;
			}
			else{
				 count++;
			}
		}
		System.out.println ("Out of 100 rolls of the two dice, the total of both the dice greater than or equal to 10 was " + total + " times");
    }
  }

Richard MacCutchan13-Mar-20 4:30

13-Mar-20 4:30

Nice but ...
... you should create the Random object once only, before the for loop. Random classes tend to be pseudo rather than 'true' random number generators, and as such will generally produce the same sequence each time. You can improve on this by adding a seed value to the constructor as described at Random (Java Platform SE 8 )[^], but it is still best to create it only once, before using it in a loop.

MallardsReach13-Mar-20 6:33

13-Mar-20 6:33

Thanks again Richard, as I have said I am only starting out with Java and saw this post so thought it would give me something to have a go at. Will look at the link you have provided.

Richard MacCutchan13-Mar-20 6:49

13-Mar-20 6:49

If you also want to see some excellent learning materials then take a look at The Java™ Tutorials[^].

MallardsReach13-Mar-20 7:15

Transfer data from SQL database to populate spinner

13-Mar-20 7:15

Will look at the tutorials.
Tried the random seed and always got the same number every time I ran the program
So did this and it seems to work, at least I get different result each time.

Java

Random rnd = new Random(); // create a new object of Random class
rnd.setSeed(System.currentTimeMillis());

Member 1475169121-Feb-20 5:55

Member 14751691

21-Feb-20 5:55

Hello Everyone! I have found some code and developed a database that you can enter a student's name and their parents phone number. However, I am stuck. I need the data from the SQL database to populate and spinner, but I don't even know where to begin with coding that. I would appreciate any help that could be given. Here is the code I am currently using (I did get this code online and tailored it to work with my version of Android Studio. (I am using version 3.5)

The following code is in MainActivity.java

package codebind.example.sqliteoperations;

import android.os.Bundle;
import android.view.View;
import android.widget.EditText;

import androidx.appcompat.app.AppCompatActivity;

public class MainActivity extends AppCompatActivity {
    EditText Name, Pass , updateold, updatenew, delete;
    myDbAdapter helper;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Name= (EditText) findViewById(R.id.editName);
        Pass= (EditText) findViewById(R.id.editPass);
        updateold= (EditText) findViewById(R.id.editText3);
        updatenew= (EditText) findViewById(R.id.editText5);
        delete = (EditText) findViewById(R.id.editText6);

        helper = new myDbAdapter(this);
    }
    public void addUser(View view)
    {
        String t1 = Name.getText().toString();
        String t2 = Pass.getText().toString();
        if(t1.isEmpty() || t2.isEmpty())
        {
            Message.message(getApplicationContext(),"Enter Both Name and Password");
        }
        else
        {
            long id = helper.insertData(t1,t2);
            if(id<=0)
            {
                Message.message(getApplicationContext(),"Insertion Unsuccessful");
                Name.setText("");
                Pass.setText("");
            } else
            {
                Message.message(getApplicationContext(),"Insertion Successful");
                Name.setText("");
                Pass.setText("");
            }
        }
    }

    public void viewdata(View view)
    {
        String data = helper.getData();
        Message.message(this,data);
    }

    public void update( View view)
    {
        String u1 = updateold.getText().toString();
        String u2 = updatenew.getText().toString();
        if(u1.isEmpty() || u2.isEmpty())
        {
            Message.message(getApplicationContext(),"Enter Data");
        }
        else
        {
            int a= helper.updateName( u1, u2);
            if(a<=0)
            {
                Message.message(getApplicationContext(),"Unsuccessful");
                updateold.setText("");
                updatenew.setText("");
            } else {
                Message.message(getApplicationContext(),"Updated");
                updateold.setText("");
                updatenew.setText("");
            }
        }

    }
    public void delete( View view)
    {
        String uname = delete.getText().toString();
        if(uname.isEmpty())
        {
            Message.message(getApplicationContext(),"Enter Data");
        }
        else{
            int a= helper.delete(uname);
            if(a<=0)
            {
                Message.message(getApplicationContext(),"Unsuccessful");
                delete.setText("");
            }
            else
            {
                Message.message(this, "DELETED");
                delete.setText("");
            }
        }
    }
}

The following code is in myDbAdapter.java

package codebind.example.sqliteoperations;

import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;


public class myDbAdapter {
    myDbHelper myhelper;
    public myDbAdapter(Context context)
    {
        myhelper = new myDbHelper(context);
    }

    public long insertData(String name, String pass)
    {
        SQLiteDatabase dbb = myhelper.getWritableDatabase();
        ContentValues contentValues = new ContentValues();
        contentValues.put(myDbHelper.NAME, name);
        contentValues.put(myDbHelper.MyPASSWORD, pass);
        long id = dbb.insert(myDbHelper.TABLE_NAME, null , contentValues);
        return id;
    }

    public String getData()
    {
        SQLiteDatabase db = myhelper.getWritableDatabase();
        String[] columns = {myDbHelper.UID,myDbHelper.NAME,myDbHelper.MyPASSWORD};
        Cursor cursor =db.query(myDbHelper.TABLE_NAME,columns,null,null,null,null,null);
        StringBuffer buffer= new StringBuffer();
        while (cursor.moveToNext())
        {
            int cid =cursor.getInt(cursor.getColumnIndex(myDbHelper.UID));
            String name =cursor.getString(cursor.getColumnIndex(myDbHelper.NAME));
            String  password =cursor.getString(cursor.getColumnIndex(myDbHelper.MyPASSWORD));
            buffer.append(cid+ "   " + name + "   " + password +" \n");
        }
        return buffer.toString();
    }

    public  int delete(String uname)
    {
        SQLiteDatabase db = myhelper.getWritableDatabase();
        String[] whereArgs ={uname};

        int count =db.delete(myDbHelper.TABLE_NAME ,myDbHelper.NAME+" = ?",whereArgs);
        return  count;
    }

    public int updateName(String oldName , String newName)
    {
        SQLiteDatabase db = myhelper.getWritableDatabase();
        ContentValues contentValues = new ContentValues();
        contentValues.put(myDbHelper.NAME,newName);
        String[] whereArgs= {oldName};
        int count =db.update(myDbHelper.TABLE_NAME,contentValues, myDbHelper.NAME+" = ?",whereArgs );
        return count;
    }

    static class myDbHelper extends SQLiteOpenHelper
    {
        private static final String DATABASE_NAME = "myDatabase";    // Database Name
        private static final String TABLE_NAME = "myTable";   // Table Name
        private static final int DATABASE_Version = 1;    // Database Version
        private static final String UID="_id";     // Column I (Primary Key)
        private static final String NAME = "Name";    //Column II
        private static final String MyPASSWORD= "Password";    // Column III
        private static final String CREATE_TABLE = "CREATE TABLE "+TABLE_NAME+
                " ("+UID+" INTEGER PRIMARY KEY AUTOINCREMENT, "+NAME+" VARCHAR(255) ,"+ MyPASSWORD+" VARCHAR(225));";
        private static final String DROP_TABLE ="DROP TABLE IF EXISTS "+TABLE_NAME;
        private Context context;

        public myDbHelper(Context context) {
            super(context, DATABASE_NAME, null, DATABASE_Version);
            this.context=context;
        }

        public void onCreate(SQLiteDatabase db) {

            try {
                db.execSQL(CREATE_TABLE);
            } catch (Exception e) {
                Message.message(context,""+e);
            }
        }

        @Override
        public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
            try {
                Message.message(context,"OnUpgrade");
                db.execSQL(DROP_TABLE);
                onCreate(db);
            }catch (Exception e) {
                Message.message(context,""+e);
            }
        }
    }
}

The following code is in Message.java

package codebind.example.sqliteoperations;

import android.content.Context;
import android.widget.Toast;

public class Message {
    public static void message(Context context, String message) {
        Toast.makeText(context, message, Toast.LENGTH_LONG).show();
    }
}

The following code is in activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"

    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/activity_main"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="#4B1414">

    <TextView
        android:id="@+id/textView"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_alignParentStart="true"
        android:layout_alignParentLeft="true"
        android:layout_alignParentTop="true"
        android:layout_marginTop="12dp"
        android:gravity="center"
        android:text="Student Name"
        android:textColor="#FFFFFF"
        android:textSize="18sp"
        android:textStyle="bold|italic" />

    <EditText
        android:id="@+id/editName"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_below="@+id/textView"
        android:layout_alignParentEnd="true"
        android:layout_alignParentRight="true"
        android:ems="10"
        android:gravity="center_vertical|center"
        android:hint="Enter Name"
        android:inputType="textPersonName"
        android:textColor="#FFFFFF"
        android:textStyle="bold|italic" />

    <TextView
        android:id="@+id/textView2"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_below="@+id/editName"
        android:layout_alignParentEnd="true"
        android:layout_alignParentRight="true"
        android:layout_marginTop="13dp"
        android:gravity="center"
        android:hint="Enter Password"
        android:text="Parent Number"
        android:textColor="#FFFFFF"
        android:textSize="18sp"
        android:textStyle="bold|italic" />

    <Button
        android:id="@+id/button2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignBaseline="@+id/button"
        android:layout_alignEnd="@+id/button4"
        android:layout_alignRight="@+id/button4"
        android:layout_alignBottom="@+id/button"
        android:onClick="viewdata"
        android:text="View Data"
        android:textSize="18sp"
        android:textStyle="bold|italic" />

    <Button
        android:id="@+id/button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_below="@+id/editPass"
        android:layout_alignParentStart="true"
        android:layout_alignParentLeft="true"
        android:layout_marginStart="28dp"
        android:layout_marginLeft="28dp"
        android:layout_marginTop="23dp"
        android:onClick="addUser"
        android:text="Add User"
        android:textSize="18sp"
        android:textStyle="bold|italic" />

    <Button
        android:id="@+id/button3"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_below="@+id/editText3"
        android:layout_alignStart="@+id/button4"
        android:layout_alignLeft="@+id/button4"
        android:layout_marginTop="13dp"
        android:onClick="update"
        android:text="Update"
        android:textStyle="normal|bold" />

    <EditText
        android:id="@+id/editText6"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignTop="@+id/button4"
        android:layout_alignParentStart="true"
        android:layout_alignParentLeft="true"
        android:layout_toStartOf="@+id/button2"
        android:layout_toLeftOf="@+id/button2"
        android:ems="10"
        android:freezesText="false"
        android:hint="Enter Name to Delete Data"
        android:inputType="textPersonName" />

    <Button
        android:id="@+id/button4"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentEnd="true"
        android:layout_alignParentRight="true"
        android:layout_alignParentBottom="true"
        android:layout_marginEnd="21dp"
        android:layout_marginRight="21dp"
        android:layout_marginBottom="41dp"
        android:onClick="delete"
        android:text="Delete"
        android:textStyle="normal|bold"
        tools:ignore="RelativeOverlap" />

    <EditText
        android:id="@+id/editText3"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_below="@+id/button"
        android:layout_alignParentStart="true"
        android:layout_alignParentLeft="true"
        android:layout_marginStart="7dp"
        android:layout_marginLeft="7dp"
        android:layout_marginTop="47dp"
        android:ems="10"
        android:hint="Current Name"
        android:inputType="textPersonName"
        android:textColor="#FFFFFF"
        android:textSize="14sp"
        android:textStyle="bold|italic" />

    <EditText
        android:id="@+id/editPass"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_below="@+id/textView2"
        android:layout_alignParentStart="true"
        android:layout_alignParentLeft="true"
        android:layout_marginTop="11dp"
        android:ems="10"
        android:gravity="center_vertical|center"
        android:hint="Enter Number"
        android:inputType="textPassword"
        android:textAllCaps="false"
        android:textSize="18sp"
        android:textStyle="normal|bold" />

    <EditText
        android:id="@+id/editText5"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignStart="@+id/editText3"
        android:layout_alignLeft="@+id/editText3"
        android:layout_alignTop="@+id/button3"
        android:layout_marginTop="32dp"
        android:ems="10"
        android:hint="New Name"
        android:inputType="textPersonName"
        android:textSize="14sp"
        android:textStyle="bold|italic" />

</RelativeLayout>

Thanks you for all your help!

Re: Transfer data from SQL database to populate spinner

Richard MacCutchan21-Feb-20 6:10

Re: Transfer data from SQL database to populate spinner

21-Feb-20 6:10

You need to put the data into an object that the spinner can use to populate itself, like an ArrayAdapter. See Spinners | Android Developers[^].

Member 1475169121-Feb-20 7:38

Member 14751691

21-Feb-20 7:38

Thank you. How would I go about doing that? I am fairly new to android studio and this is all new to me.

Re: Transfer data from SQL database to populate spinner

Richard MacCutchan21-Feb-20 22:08

Re: Transfer data from SQL database to populate spinner

21-Feb-20 22:08

Read the documentation for the classes that you are trying to use. Also look at some of the Android tutorials here on CodeProject: https://www.codeproject.com/KB/android/[^]

Member 1475169122-Feb-20 14:38

Member 14751691

22-Feb-20 14:38

Thank you very much!

Json Manager Project (Need Critique/Possible Tips)

Member 147385357-Feb-20 16:20

Member 14738535

7-Feb-20 16:20

Hi Guys,
This is my first post in this community. And I hope I am not screwing up.

Anyways I built a package to process Json data as a string into objects as nodes stored in nodes in a tree. It is far from complete, but the parsing and node tree building methods are set and the manager class is commenting.

This is also important to me as I am building a portfolio, and I i would be grateful if someone can take another look to see if anything can be done more efficiently and possible let me know where i went wrong with commenting and examples of how you would do it.

Anyways the main class link in github is bellow:
JVJsonManager/Json.java at master · Clowcadia/JVJsonManager · GitHub[^]

Re: Json Manager Project (Need Critique/Possible Tips)

Richard MacCutchan7-Feb-20 22:06