Android Development for Beginners : Cola Wars Example

MainActivity.java

public class MainActivity extends AppCompatActivity {
    ...
    public void voteUdacicola(View view) {
        int udacicolaVotes = 0;
        udacicolaVotes = udacicolaVotes + 1;
    }

    public void votePepcity(View view) {
        int pepcityVotes;
        pepcityVotes = pepcityVotes + 1;
    }

    public void showMeVotes(View view) {
        display(udacicolaVotes + " vs. " + pepcityVotes);
    }
    ...
}

public class MainActivity extends AppCompatActivity {
...
int udacicolaVotes = 0;
int pepcityVotes = 0;

public void voteUdacicola(View view) {
           udacicolaVotes = udacicolaVotes + 1;
}

public void votePepcity(View view) {
           pepcityVotes = pepcityVotes + 1;
}

public void showMeVotes(View view) {
    display(udacicolaVotes + " vs. " + pepcityVotes);
}
...

}

if someone is still looking for a good explanation of local vs. global variables, I really liked this short, easy to understand explanation https://www.codecademy.com/en/forum_questions/514900b642e721e65d0003f1

Both of variables are local and both of them must be global for reachable from anypoint.

good job thank you

This Code have some error
1- int pepcityVotes; not set initial value of variable name
2- udacicolaVotes & pepcityVotes are local variable not Global variable so make error

The Correct Code Is

int udacicolaVotes = 0, pepcityVotes = 0;

public void voteUdacicola(View view) {
    udacicolaVotes = udacicolaVotes + 1;
}

public void votePepcity(View view) {
    pepcityVotes = pepcityVotes + 1;
}

public void showMeVotes(View view) {
    display(udacicolaVotes + " vs. " + pepcityVotes);
}

globbal is in the begining
local is in lines

Errors:

• local variables out of scope.
• local variables cannot be used as counters.
• one of the local variables is not initialized.

thanks

both variables are local and they should be global for all methods to know about them

Udacicola and Pepcity should be both global to be used in showMeVotes() method. Cool example

thanks

soo... but how will become this code on
MainActivity.java and how will become the acitivityMain.xml with this ?

it gives me error

should be global Variable so other method can use it . As example here ShowMeVotes , otherwise it will give us error.

im need the xml code of voting ...

@mohammed74 you can use mine below but you need to change android:src to your own image
`

<LinearLayout
    android:layout_width="wrap_content"
    android:layout_height="wrap_content">

<TextView
    android:id="@+id/display_text_view"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="WHICH DO YOU PREFER?"
    android:textColor="#000"
    android:shadowColor="#3e0909"
    android:layout_marginBottom="30dp"
    android:textSize="45sp" />

    </LinearLayout>

<View
    android:layout_width="match_parent"
    android:layout_height="3dp"
    android:background="#000"/>

<RelativeLayout
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_marginTop="35dp">

    <ImageView
        android:layout_width="150dp"
        android:layout_height="150dp"
        android:id="@+id/cocacola"
        android:layout_alignParentLeft="true"
        android:src="@drawable/cola"
        android:layout_marginBottom="20dp"/>

    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_below="@id/cocacola"
        android:gravity="center"
        android:text="Vote"
        android:layout_alignParentLeft="true"
        android:background="#b71f1f"
        android:onClick="voteUdacicola"
        android:textColor="#fff"
        android:layout_marginLeft="35dp"/>

    <ImageView
        android:layout_width="150dp"
        android:layout_height="150dp"
        android:src="@drawable/pepsi"
        android:id="@+id/pepsi"
        android:layout_alignParentTop="true"
        android:layout_alignParentRight="true"
        android:layout_alignParentEnd="true"
        android:layout_marginBottom="20dp"/>

    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_below="@id/pepsi"
        android:gravity="center"
        android:text="Vote"
        android:layout_alignParentRight="true"
        android:background="#285fbf"
        android:textColor="#fff"
        android:onClick="votePepcity"
        android:layout_marginRight="30dp"/>

</RelativeLayout>

`

no

very nice .. thanx

thank you

<LinearLayout
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:orientation="horizontal"
    android:padding="8dp">

    <TextView
        android:id="@+id/display_text_view1"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_weight="1"
        android:gravity="center"
        android:text="0"
        android:textSize="45sp" />

    <TextView
        android:id="@+id/display_text_view2"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_weight=".55"
        android:gravity="center"
        android:text="vs"
        android:textSize="45sp" />

    <TextView
        android:id="@+id/display_text_view3"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_weight="1"
        android:gravity="center"
        android:text="0"
        android:textSize="45sp" />
</LinearLayout>

<LinearLayout
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:orientation="horizontal"
    android:padding="8dp">

    <Button
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_weight="1"
        android:onClick="votePepcity"
        android:text="pepcity" />

    <Button
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_weight="1"
        android:onClick="voteUdacicola"
        android:text="udacicola" />
</LinearLayout>

public class MainActivity extends AppCompatActivity {
int pepcityVotes = 0;
int udacicolaVotes = 0;

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

public void votePepcity(View view) {
    pepcityVotes = pepcityVotes + 1;
    display(pepcityVotes);
    return;
}

public void voteUdacicola(View view) {
    udacicolaVotes = udacicolaVotes + 1;
    display1(udacicolaVotes);
    return;
}

public void display(int p) {
    TextView t1 = (TextView) findViewById(R.id.display_text_view1);
    t1.setText("" + p);
}

public void display1(int c) {
    TextView t2 = (TextView) findViewById(R.id.display_text_view3);
    t2.setText("" + c);
}

}

the parent layout is linearLayout vertical

can somebody please provide full code of xml and java for these examples............... i am getting very confused in this lesson 3

Both of variables are local and both of them must be global for reachable from anypoint.

having error

package com.example.ummurasul.practice;

import androidx.appcompat.app.AppCompatActivity;

import android.os.Bundle;
import android.view.Menu;
import android.view.View;
import android.widget.TextView;

public class MainActivity extends AppCompatActivity {
int pepsiVotes = 0;
int spriteVotes =0;

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

public void voteUdacicola(View view) {
    spriteVotes = spriteVotes + 1;
    display1(spriteVotes);
    return;
}

public void votePepcity(View view) {
    pepsiVotes =pepsiVotes + 1;
    display(pepsiVotes);
    return;
}

}

**public void display(int p) {
TextView t1 = (TextView) findViewById(R.id.cocacola);
t1.setText("" + p);
}

public void display1(int c) {
    TextView t2 = (TextView) findViewById(R.id.pepsi);
    t2.setText("" + c);
}**

the error is on de above code

@Kukkulum
A global variable is initialized at the starting of the code it is global means other methods can be used this variable but local variable is initialized inside a method and there local members can used it not all the methods.

Thank you for your explanation. It is helpful to understand the difference.

best android course on this planet

very nice course