IMPORTANT: Remember to add your package name before you copy and paste this java code into the JustJava app's MainActivity.java file.

MainActivity.java

/**
 * IMPORTANT: Make sure you are using the correct package name. 
 * This example uses the package name:
 * package com.example.android.justjava
 * If you get an error when copying this code into Android studio, update it to match teh package name found
 * in the project's AndroidManifest.xml file.
 **/
 
 package com.example.android.justjava; 
 


import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.TextView;

/**
 * This app displays an order form to order coffee.
 */
public class MainActivity extends AppCompatActivity {

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

    /**
     * This method is called when the order button is clicked.
     */
    public void submitOrder(View view) {
        display(1);
    }

    /**
     * This method displays the given quantity value on the screen.
     */
    private void display(int number) {
        TextView quantityTextView = (TextView) findViewById(R.id.quantity_text_view);
        quantityTextView.setText("" + number);
    }
}

Hi there,

if you have the latest version od Android studio, you won't have the .java document, but it will be in Kotlin. You need to translate Java into the Kotlin (it is done automatically) and than you'll have only 2 issues with mainActivity and quantity_text_view. This is how it is solved:

`package com.example.justjava;

import android.R import android.os.Bundle import android.view.View import android.widget.TextView import androidx.appcompat.app.AppCompatActivity

/**

This app displays an order form to order coffee. */ class MainActivity : AppCompatActivity() { override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) setContentView(com.example.justjava.R.layout.activity_main) }

/**
 * This method is called when the order button is clicked.
 */
fun submitOrder(view: View?) {
    display(1)
}

/**
 * This method displays the given quantity value on the screen.
 */
private fun display(number: Int) {
    val quantityTextView = findViewById<View>(com.example.justjava.R.id.quantity_text_view) as TextView
    quantityTextView.text = "" + number
}

}`

Thank you so much totally worked for me and was looking for it since so long

This is what worked for me:

/**

• IMPORTANT: Make sure you are using the correct package name.
• This example uses the package name:
• package com.example.android.justjava
• If you get an error when copying this code into Android studio, update it to match teh package name found
• in the project's AndroidManifest.xml file.
  */
  package android.example.justjava

import android.os.Bundle
import android.view.View
import android.widget.TextView
import androidx.appcompat.app.AppCompatActivity

/**

• This app displays an order form to order coffee.
  */
  class MainActivity : AppCompatActivity() {
  override fun onCreate(savedInstanceState: Bundle?) {
  super.onCreate(savedInstanceState)
  setContentView(R.layout.activity_main)
  }

  /**

  • This method is called when the order button is clicked.
    */
    fun submitOrder(view: View?) {
    display(1)
    }

  /**

  • This method displays the given quantity value on the screen.
    */
    private fun display(number: Int) {
    val quantityTextView = findViewById(R.id.quantity_text_view) as TextView
    quantityTextView.text = "" +number
    }
    }

This is the solution that worked for me. I was getting AppCompactActivity, onCreate, findViewById errors. Solution - Replacing the import android.support.v7.AppCompatActivity; with import androidx.appcompat.app.AppCompatActivity; This was the Error -> This is after implementing the solution ->

that worked for me as well

Cannot resolve method 'createOrderSummary' in 'MainActivity' problem
Cannot resolve method 'displayMessage' in 'MainActivity' problem
Cannot resolve symbol 'quantity_text_view'
Method 'submitOrder(android.view.View)' is never used
Private method 'display(int)' is never used
Casting 'findViewById(...)' to 'TextView' is redundant
Do not concatenate text displayed with setText. Use resource string with placeholders. problem

please help on these issues

Actually, I used the recent version Android studio and the "MainActivity" is kotlin which is MainActivity.kt and the following code is auto converted to it and error free

package com.example.justjava

import android.os.Bundle
import android.view.View
import android.widget.TextView
import androidx.appcompat.app.AppCompatActivity

/**
*

• This app displays an order form to order coffee.
  */
  class MainActivity : AppCompatActivity() {
  override fun onCreate(savedInstanceState: Bundle?) {
  super.onCreate(savedInstanceState)
  setContentView(R.layout.activity_main)
  }

  /**

  • This method is called when the order button is clicked.
    */
    fun submitOrder(view: View?) {
    display(1)
    }

  private fun display(number: Int) {
  val quantityTextView = findViewById(R.id.quantity_text_view)
  quantityTextView.text = "" + number
  }
  }

After using all the suggestions given it still says R package does not exist. What do I do???

I would love to rectify those errors, could you tell me how did you remove all those errors and now have one only ?

hi i fix tahe error but when i thche the button no thing haapn

finally i did it after hard works
try this code
package _"com.example.android.justjava" -(make sure to write you package name)

import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
import androidx.appcompat.app.AppCompatActivity;
public class MainActivity extends AppCompatActivity {

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    TextView num = findViewById(R.id.num);
    Button order1 = findViewById(R.id.order);
    /**
     * This method is called when the order button is clicked.
     */
    order1.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            display1(1);
        }
        /**
         * This method displays the given quantity value on the screen.
         */
        private void display1(int number)
        {
            //  TextView quantity = (TextView) findViewById(R.id.quantity);
            num.setText("" + number);
        }


    });
}

}

After using all the suggestions given it still says R package does not exist. What do I do???

I would love to rectify those errors, could you tell me how did you remove all those errors and now have one only ?

Hy, Which version of Android Studio are you using?

its my last project of the Android Developers final project for Congratulations to Nani

BUTTON CLICK
Modify activity_main.xml to add this Button XML attribute.
android:onClick = "submitOrder"
Replace entire MainActivity.java file with the file provided in the link to the code.
Run app on device. what can i do? pls tell me the answer of these Question
What happens when you click on the Button?

Modify activity_main.xml to add this Button XML attribute.
android:onClick = "submitOrder"
Replace entire MainActivity.java file with the file provided in the link to the code.
Run app on device.
What happens when you click on the Button?
Solution

1. I modify activity_main.xml to onclick attribute
2. I copy the MainActivity.java by new version ,then I click to run,it display nicely
3. it update the quantity value one
   I still didn't get the answer of the question ? Help Help

fun main()
{
mood == "happy" && weather == "Sunny" -> "go for a walk"
else -> "Stay home and read."
if else->
whatShouldIDoToday("sad")
}

Create a program that suggests an activity based on various parameters.

1. Start in a new file with a main function.
2. From main(), create a function, whatShouldIDoToday().
3. Let the function have three parameters.
   mood: a required string parameter
   weather: a string parameter that defaults to "sunny"
   temperature: an Integer parameter that defaults to 24 (Celsius).
4. Use a when construct to return some activities based on combinations of conditions. For example:
   mood == "happy" && weather == "Sunny" -> "go for a walk"
   else -> "Stay home and read."
5. Copy/paste your finished function into REPL, and call it with combinations of arguments. For example:
   whatShouldIDoToday("sad")

Stay home and read.

fun describe(obj: Any): String =when(mood == "happy" && weather == "Sunny" -> "go for a walk")
{
mood -> "happy"
"sunny" -> "Go for a walk"
weather -> "Stay home and read."
else -> whatShouldIDoToday("Sad")
}
fun main() {
println(describe(happy))
println(describe("sunny"))
println(describe(weather))
println(describe("WhatShouldIDoToday"))

}

//The output is //
Go for a walk
Stay home and read.
Sad