Question

Okay so I’m making a simple rock, paper, scissors game for android.
So far I have the following:

package com.example.digitoolz;

import java.util.Random;
import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.widget.ImageButton;
import android.widget.Toast;

public class GameActivity extends Activity {
    private int userChoice;
    private int compChoice;

    private int userScore = 0;
    private int compScore = 0;

    private Toast winnerToast;

    public void onCreate(Bundle savedInstanceState){
        super.onCreate(savedInstanceState);
        setContentView(R.layout.game_button);


        ImageButton rockbutton = (ImageButton)findViewById(R.id.rock_button);
        rockbutton.setOnClickListener(new View.OnClickListener(){
            @Override
            public void onClick(View v){
                userChoice = 0;         
                compChoiceSelector();
                winSelect();
            }
        });

        ImageButton paperbutton = (ImageButton)findViewById(R.id.paper_button);
        paperbutton.setOnClickListener(new View.OnClickListener(){
            @Override
            public void onClick(View v){
                userChoice = 1;         
                compChoiceSelector();
                winSelect();
            }
        });


        ImageButton scissorsbutton = (ImageButton)findViewById(R.id.scissors_button);
        scissorsbutton.setOnClickListener(new View.OnClickListener(){
            @Override
            public void onClick(View v){
                userChoice = 2;     
                compChoiceSelector();
                winSelect();
            }
        });
    }   

        public void compChoiceSelector(){
            Random ran = new Random();
            compChoice = ran.nextInt(0) + 3;
        }

        public void winSelect(){
            if(userChoice == compChoice){
                winnerToast.setText("It's a Draw!");
                }else if (userChoice == 0 && compChoice == 1){
                    winnerToast.setText("Paper beats Rock! You Lose!");
                    compScore++;
                }else if (userChoice == 0 && compChoice == 2){
                    winnerToast.setText("Rock beats Scissorcs! You Win!");
                    userScore++;
                }else if (userChoice == 1 && compChoice == 0){
                    winnerToast.setText("Paper beats Rock! You Win!");
                    userScore++;
                }else if (userChoice == 1 && compChoice == 2){
                    winnerToast.setText("Scissors beats paper! You Lose!");
                    compScore++;
                }else if (userChoice == 2 && compChoice == 0){
                    winnerToast.setText("Rock beats scissors! You Lose!");
                    compScore++;
                }else if (userChoice == 2 && compChoice == 1){
                    winnerToast.setText("Scissors beats paper... You Win.");
                    userScore++;
            }else{
                    winnerToast.setText("");
            }
        }
    }

Basically, when it come to pressing any of the 3 buttons(rock, paper or scissors). I get a popup saying “Unfortunately digitoolz has stopped working.

I have no idea why this is happening!?
Please can someone help me!

Thank you to all in advance! 🙂

12-21 01:02:19.711: D/AndroidRuntime(573): Shutting down VM
12-21 01:02:19.721: W/dalvikvm(573): threadid=1: thread exiting with uncaught exception (group=0x409961f8)
12-21 01:02:19.782: E/AndroidRuntime(573): FATAL EXCEPTION: main
12-21 01:02:19.782: E/AndroidRuntime(573): java.lang.IllegalArgumentException
12-21 01:02:19.782: E/AndroidRuntime(573):  at java.util.Random.nextInt(Random.java:187)
12-21 01:02:19.782: E/AndroidRuntime(573):  at com.example.digitoolz.GameActivity.compChoiceSelector(GameActivity.java:59)
12-21 01:02:19.782: E/AndroidRuntime(573):  at com.example.digitoolz.GameActivity$2.onClick(GameActivity.java:40)
12-21 01:02:19.782: E/AndroidRuntime(573):  at android.view.View.performClick(View.java:3480)
12-21 01:02:19.782: E/AndroidRuntime(573):  at android.view.View$PerformClick.run(View.java:13983)
12-21 01:02:19.782: E/AndroidRuntime(573):  at android.os.Handler.handleCallback(Handler.java:605)
12-21 01:02:19.782: E/AndroidRuntime(573):  at android.os.Handler.dispatchMessage(Handler.java:92)
12-21 01:02:19.782: E/AndroidRuntime(573):  at android.os.Looper.loop(Looper.java:137)
12-21 01:02:19.782: E/AndroidRuntime(573):  at android.app.ActivityThread.main(ActivityThread.java:4340)
12-21 01:02:19.782: E/AndroidRuntime(573):  at java.lang.reflect.Method.invokeNative(Native Method)
12-21 01:02:19.782: E/AndroidRuntime(573):  at java.lang.reflect.Method.invoke(Method.java:511)
12-21 01:02:19.782: E/AndroidRuntime(573):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
12-21 01:02:19.782: E/AndroidRuntime(573):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
12-21 01:02:19.782: E/AndroidRuntime(573):  at dalvik.system.NativeStart.main(Native Method)
12-21 01:07:20.110: I/Process(573): Sending signal. PID: 573 SIG: 9

new Logcat:

12-21 02:33:17.920: D/AndroidRuntime(11568): Shutting down VM
12-21 02:33:17.920: W/dalvikvm(11568): threadid=1: thread exiting with uncaught exception (group=0x40abca08)
12-21 02:33:17.930: E/AndroidRuntime(11568): FATAL EXCEPTION: main
12-21 02:33:17.930: E/AndroidRuntime(11568): java.lang.RuntimeException: This Toast was not created with Toast.makeText()
12-21 02:33:17.930: E/AndroidRuntime(11568):    at android.widget.Toast.setText(Toast.java:277)
12-21 02:33:17.930: E/AndroidRuntime(11568):    at com.example.digitoolz.GameActivity.winSelect(GameActivity.java:65)
12-21 02:33:17.930: E/AndroidRuntime(11568):    at com.example.digitoolz.GameActivity$2.onClick(GameActivity.java:42)
12-21 02:33:17.930: E/AndroidRuntime(11568):    at android.view.View.performClick(View.java:3538)
12-21 02:33:17.930: E/AndroidRuntime(11568):    at android.view.View$PerformClick.run(View.java:14319)
12-21 02:33:17.930: E/AndroidRuntime(11568):    at android.os.Handler.handleCallback(Handler.java:608)
12-21 02:33:17.930: E/AndroidRuntime(11568):    at android.os.Handler.dispatchMessage(Handler.java:92)
12-21 02:33:17.930: E/AndroidRuntime(11568):    at android.os.Looper.loop(Looper.java:156)
12-21 02:33:17.930: E/AndroidRuntime(11568):    at android.app.ActivityThread.main(ActivityThread.java:5045)
12-21 02:33:17.930: E/AndroidRuntime(11568):    at java.lang.reflect.Method.invokeNative(Native Method)
12-21 02:33:17.930: E/AndroidRuntime(11568):    at java.lang.reflect.Method.invoke(Method.java:511)
12-21 02:33:17.930: E/AndroidRuntime(11568):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
12-21 02:33:17.930: E/AndroidRuntime(11568):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
12-21 02:33:17.930: E/AndroidRuntime(11568):    at dalvik.system.NativeStart.main(Native Method)

Answer 1

Your first problem is that nextInt() needs a number above 0. Anything supplied to nextInt() that is <= 0 throws that IllegalArgumentException.

Your other problem may be:
You don’t seem to be instantiating your winnerToast. It is global, but your code never actually does winnerToast = new Toast(this); You should probably add this line of code in your onCreate() method to avoid a NullPointerException.