Java android在运行时崩溃

Question

I have so far coded a Application that prompts the user to guess a number between 1 and 20. I'm struggling to see why the app crashes when it takes the users number. The first method works where it takes the name. The guessingGame method is where it handles the users input and checks whether it is equal to the random number generated by the app.

package Ass.example.task1c3433870;

   import java.util.Random;

   import android.app.Activity;
   import android.os.Bundle;
   import android.text.TextUtils;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;
import android.view.View.OnClickListener;

public class MainActivity extends Activity {

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

    @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) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();
        if (id == R.id.action_settings) {
            return true;
        }
        return super.onOptionsItemSelected(item);
    }




    public void onClick(View v) {


                EditText name = (EditText) findViewById(R.id.name);
            String sUsername = name.getText().toString();
            TextView displayName = (TextView) findViewById(R.id.displayName);

            if(TextUtils.isEmpty(sUsername)) {
                displayName.setText(sUsername);

            }else{

            displayName.setText(sUsername);
            Toast.makeText(MainActivity.this, "Button Clicked", Toast.LENGTH_SHORT).show();

            }
    }
            public void guessingGame(View v){   


            EditText guess = (EditText) findViewById(R.id.guess);



            TextView displayGuess = (TextView) findViewById(R.id.displayGuess);
            TextView numAttempts = (TextView) findViewById(R.id.numAttempts);
            TextView result = (TextView) findViewById(R.id.Result);
            TextView guessCorrect = (TextView) findViewById(R.id.guessCorrect);
            TextView resetCount = (TextView) findViewById(R.id.resetCount);

            int correctGuess = Integer.parseInt(guessCorrect.getText().toString());
            int guessValue = Integer.parseInt(guess.getText().toString());

            int numAttemptsValue = `enter code`enter code here` here`Integer.parseInt(numAttempts.getText().toString());
            int resetCounter = Integer.parseInt(resetCount.getText().toString());


            if (guessValue < 1)
            {
                result.setText("Enter valid number");
                guess.getText().clear();

            }
            else if (guessValue > 20)
            {
                result.setText("Enter valid number");
                guess.getText().clear();

            }else
            {
                int min = 1;
                int max = 20;

                numAttemptsValue -= 1;
                numAttempts.setText(Integer.toString(numAttemptsValue));

                if(numAttemptsValue > 1)
                {
                    Random r = new Random();
                    int i = r.nextInt(max - min + 1) + min;

                    int randomNumber =  i;
                    displayGuess.setText(Integer.toString(guessValue));

                    if(randomNumber > guessValue)

                    {
                        result.setText("Low Guess");
                    }

                        else if(randomNumber < guessValue)
                        {

                        result.setText("High Guess");

                        }
                        else if (randomNumber == guessValue)
                        {
                            result.setText("Correct!!!!!");
                            correctGuess += 1;
                               guessCorrect.setText(Integer.toString(correctGuess));

                        }

                        else if (numAttemptsValue == 0)
                            {
                            result.setText("No more lives! GAME OVER!");
                            numAttemptsValue += 10;
                            numAttempts.setText(5);
                            resetCounter += 1;
                            resetCount.setText(Integer.toString(correctGuess));
                            }


                }   
            }


            }

    }

This is the log cat from when ran. The issue is only based in the guessingGame method. I would be very grateful if someone would be able to point me in the right direction? Thanks.

   03-14 16:21:33.500: D/dalvikvm(796): Not late-enabling CheckJNI (already on)
   03-14 16:21:35.050: D/gralloc_goldfish(796): Emulator without GPU emulation   detected.
  03-14 16:21:45.910: D/AndroidRuntime(796): Shutting down VM
  03-14 16:21:45.910: W/dalvikvm(796): threadid=1: thread exiting with uncaught   exception (group=0xb4ad2ba8)
  03-14 16:21:45.960: E/AndroidRuntime(796): FATAL EXCEPTION: main
  03-14 16:21:45.960: E/AndroidRuntime(796): Process: Ass.example.task1c3433870, PID: 796
    03-14 16:21:45.960: E/AndroidRuntime(796): java.lang.IllegalStateException: Could not execute method of the activity
    03-14 16:21:45.960: E/AndroidRuntime(796):  at android.view.View$1.onClick(View.java:3823)
    03-14 16:21:45.960: E/AndroidRuntime(796):  at  android.view.View.performClick(View.java:4438)
   03-14 16:21:45.960: E/AndroidRuntime(796):   at android.view.View$PerformClick.run(View.java:18422)
  03-14 16:21:45.960: E/AndroidRuntime(796):    at android.os.Handler.handleCallback(Handler.java:733)
  03-14 16:21:45.960: E/AndroidRuntime(796):    at android.os.Handler.dispatchMessage(Handler.java:95)
   03-14 16:21:45.960: E/AndroidRuntime(796):   at android.os.Looper.loop(Looper.java:136)
   03-14 16:21:45.960: E/AndroidRuntime(796):   at android.app.ActivityThread.main(ActivityThread.java:5017)
  03-14 16:21:45.960: E/AndroidRuntime(796):    at java.lang.reflect.Method.invokeNative(Native Method)
   03-14 16:21:45.960: E/AndroidRuntime(796):   at java.lang.reflect.Method.invoke(Method.java:515)
   03-14 16:21:45.960: E/AndroidRuntime(796):   at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
   03-14 16:21:45.960: E/AndroidRuntime(796):   at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
  03-14 16:21:45.960: E/AndroidRuntime(796):    at dalvik.system.NativeStart.main(Native Method)
   03-14 16:21:45.960: E/AndroidRuntime(796): Caused by: java.lang.reflect.InvocationTargetException
    03-14 16:21:45.960: E/AndroidRuntime(796):  at java.lang.reflect.Method.invokeNative(Native Method)
    03-14 16:21:45.960: E/AndroidRuntime(796):  at java.lang.reflect.Method.invoke(Method.java:515)
   03-14 16:21:45.960: E/AndroidRuntime(796):   at android.view.View$1.onClick(View.java:3818)
   03-14 16:21:45.960: E/AndroidRuntime(796):   ... 11 more
   03-14 16:21:45.960: E/AndroidRuntime(796): Caused by: java.lang.NumberFormatException: Invalid int: ""
   03-14 16:21:45.960: E/AndroidRuntime(796):   at java.lang.Integer.invalidInt(Integer.java:137)
   03-14 16:21:45.960: E/AndroidRuntime(796):   at java.lang.Integer.parseInt(Integer.java:358)
    03-14 16:21:45.960: E/AndroidRuntime(796):  at java.lang.Integer.parseInt(Integer.java:331)
   03-14 16:21:45.960: E/AndroidRuntime(796):   at Ass.example.task1c3433870.MainActivity.guessingGame(MainActivity.java:77)
    03-14 16:21:45.960: E/AndroidRuntime(796):  ... 14 more
   03-14 16:27:13.464: I/Process(796): Sending signal. PID: 796 SIG: 9

Answer 1

According to your logcat it is trying to parse an empty string to an int:

03-14 16:21:45.960: E/AndroidRuntime(796): Caused by:    java.lang.NumberFormatException: Invalid int: ""

Here is your problem:

int correctGuess = Integer.parseInt(guessCorrect.getText().toString());
int guessValue = Integer.parseInt(guess.getText().toString());

You are converting an edittext to an int without first checking if they are empty or a non int value