CODEWITHSUNDEEP
androidandroid-intentevent-handlingnullpointerexception
user3006788
user3006788

Reputation: 165

having multiple choice game that will calculate the score of the user but the system crush out

i have a sample android application that will display flag of coutry and multiple choice using radio button and each time the user check one of the answers the system will check if true and add 25 points to its score using intent to pass from activity to another with transferring the data mean the score until the user play 4 times to get to the end where the system will display his score .

until now i did the MainActivity that pass the data to the second but the problem is that the system force to close and in the log cat this what its display:

can anyone help me to solve this problem ????

logcat

11-27 22:15:53.609: E/AndroidRuntime(4834): Caused by: java.lang.NullPointerException
11-27 22:15:53.609: E/AndroidRuntime(4834):     at com.devleb.flagology.SecondActivity.onCreate(SecondActivity.java:56)

MainActivity.java

package com.devleb.flagology;

import android.app.Activity;
import android.app.AlertDialog;
import android.content.DialogInterface;
import android.content.Intent;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.RadioButton;
import android.widget.RadioGroup;
import android.widget.RadioGroup.OnCheckedChangeListener;
import android.widget.Toast;

public class MainActivity extends Activity {

    Button btnS;
    RadioGroup rdgS;
    RadioButton rdS1, rdS2, rdS3, rdS4;

    private int score =0;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        rdgS = (RadioGroup) findViewById(R.id.rdg1);
        rdgS.setOnCheckedChangeListener(new OnCheckedChangeListener() {

            @Override
            public void onCheckedChanged(RadioGroup group, int checkedId) {
                // TODO Auto-generated method stub
                if (rdS1.isChecked() || rdS2.isChecked() || rdS3.isChecked()
                        || rdS4.isChecked()) {
                    btnS.setVisibility(View.VISIBLE);

                }
            }
        });

        rdS1 = (RadioButton) findViewById(R.id.rd_s1);
        rdS2 = (RadioButton) findViewById(R.id.rd_s2);
        rdS3 = (RadioButton) findViewById(R.id.rd_s3);
        rdS4 = (RadioButton) findViewById(R.id.rd_s4);

        btnS = (Button) findViewById(R.id.btn_s);
        btnS.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View v) {
                // TODO Auto-generated method stub

                Intent i = new Intent(MainActivity.this, SecondActivity.class);
                switch (rdgS.getCheckedRadioButtonId()) {
                case R.id.rd_s1:
                    i.putExtra("score", score);
                    break;
                case R.id.rd_s2:
                    i.putExtra("score", score);
                    break;
                case R.id.rd_s3:
                    i.putExtra("score", score + 25);
                    break;
                case R.id.rd_s4:
                    i.putExtra("score", score);
                    break;

                default:
                    break;
                }
                startActivity(i);

            }
        });

    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // TODO Auto-generated method stub
        switch (item.getItemId()) {
        case R.id.hint_icon:
            ShowAlertDialog();
            break;
        case R.id.about_icon:
            Toast.makeText(this, "developed by Georges Matta",
                    Toast.LENGTH_SHORT).show();
        default:
            break;
        }

        return super.onOptionsItemSelected(item);
    }

    public void ShowAlertDialog() {

        AlertDialog.Builder builder = new AlertDialog.Builder(this);
        builder.setTitle("Hint")
                .setMessage("The famouse sport is Bullfighting")
                .setCancelable(false)
                .setNegativeButton("OK", new DialogInterface.OnClickListener() {
                    public void onClick(DialogInterface dialog, int id) {
                        dialog.cancel();
                    }
                });
        AlertDialog alert = builder.create();
        alert.show();
    }

}

SecondActivity.java

package com.devleb.flagology;

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.RadioButton;
import android.widget.RadioGroup;
import android.widget.TextView;
import android.widget.RadioGroup.OnCheckedChangeListener;

public class SecondActivity extends Activity {

    Button btnI;
    RadioGroup rdgI;
    RadioButton rdI1, rdI2, rdI3, rdI4;

    // TextView txt_result;

    private int score = 0;
    int finalScore = 0;

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

        Bundle extras = getIntent().getExtras();
        if (extras != null) {
            int value = extras.getInt("score");
            finalScore = score + value;

            rdgI = (RadioGroup) findViewById(R.id.rdg2);
            rdgI.setOnCheckedChangeListener(new OnCheckedChangeListener() {

                @Override
                public void onCheckedChanged(RadioGroup group, int checkedId) {
                    // TODO Auto-generated method stub
                    if (rdI1.isChecked() || rdI2.isChecked()
                            || rdI3.isChecked() || rdI4.isChecked()) {
                        btnI.setVisibility(View.VISIBLE);

                    }
                }
            });

            rdI1 = (RadioButton) findViewById(R.id.rd_I1);
            rdI2 = (RadioButton) findViewById(R.id.rd_I2);
            rdI3 = (RadioButton) findViewById(R.id.rd_I3);
            rdI4 = (RadioButton) findViewById(R.id.rd_I4);

            btnI = (Button) findViewById(R.id.btn_s);
            btnI.setOnClickListener(new OnClickListener() {

                @Override
                public void onClick(View v) {
                    // TODO Auto-generated method stub

                    Intent i = new Intent(SecondActivity.this,
                            ThirdActivity.class);
                    switch (rdgI.getCheckedRadioButtonId()) {
                    case R.id.rd_I1:
                        i.putExtra("score", finalScore);
                        break;
                    case R.id.rd_I2:
                        i.putExtra("score", finalScore);
                        break;
                    case R.id.rd_I3:
                        i.putExtra("score", finalScore);
                        break;
                    case R.id.rd_I4:
                        i.putExtra("score", finalScore);
                        break;

                    default:
                        break;
                    }
                    startActivity(i);

                }
            });

                        }

    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.second, menu);
        return true;
    }

}

ThirdActivity.java

package com.devleb.flagology;

import android.app.Activity;
import android.os.Bundle;
import android.view.Menu;
import android.widget.TextView;

public class ThirdActivity extends Activity {

    TextView txt_result;

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

        txt_result = (TextView) findViewById(R.id.txtResult);

        Bundle extras = getIntent().getExtras();
        if (extras != null) {
            String value = String.valueOf(extras.getInt("score"));
            txt_result.setText(value);

        }
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.third, menu);
        return true;
    }

}

Upvotes: 0

Views: 420

Answers (1)

Franci Penov
Franci Penov

Reputation: 76001

I would venture to guess that your problem comes from this line:

    btnS = (Button) findViewById(R.id.btn_s);

Most likely you made changes to your main activity layout (R.layout.activity_main) and either renamed or removed the <Button> element from it. If my guess is correct, then this line will fail to find the view in the inflated layout, and your btnS object will be null, leading to the actual exception you see.

Upvotes: 1

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