在 Android Studio 中清除 EditText 时应用程序崩溃

Question

我尝试创建一个猜数游戏，我设置了一个数字范围并编辑文本供用户输入数字。我尝试输入，例如“50”，但当我尝试删除时，我只能删除“0”。如果我继续删除数字“5”，应用程序就会崩溃。这是我的 MainActivity 代码：

import java.util.Random;

public class MainActivity extends AppCompatActivity {
  TextView textViewChoice, textViewStatus;
  EditText editTextNum ;

Button buttonSetting;
SharedPreferences preferences;

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

    textViewChoice = (TextView) findViewById(R.id.textViewChoice);
    textViewStatus =(TextView) findViewById(R.id.textviewStatus);
    editTextNum = (EditText) findViewById(R.id.edittextGuess);

    buttonSetting =(Button) findViewById(R.id.buttonSetting);
    preferences = getSharedPreferences("LIMITS",MODE_PRIVATE);




    buttonSetting.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            Intent intent = new Intent(MainActivity.this, SecondaryActivity.class);
            startActivity(intent);
        }
    });
}

@Override
protected void onStart() {
    super.onStart();
    final int MinNumber = preferences.getInt("Seekbar Min", 0);
    final int MaxNumber = preferences.getInt("Seekbar Max", 0);
    textViewChoice.setText("" + MinNumber + "-" + MaxNumber);

    editTextNum.addTextChangedListener(new TextWatcher() {
        @Override
        public void beforeTextChanged(CharSequence charSequence, int i, int i1, int i2) {

        }

        @Override
        public void onTextChanged(CharSequence charSequence, int i, int i1, int i2) {
            Random random = new Random();
            int RanNum = random.nextInt(MaxNumber-MinNumber)+MinNumber;
            String StringEditNum= editTextNum.getText().toString();
            int EditNum = Integer.parseInt(StringEditNum);
            if (EditNum >RanNum){
                textViewStatus.setText("Enter Higher Number");
            }
            else if(EditNum <RanNum){
                textViewStatus.setText("Enter Lower Numer!");


            }
            else if (StringEditNum.equals("")){
                Toast.makeText(MainActivity.this,"Error!",Toast.LENGTH_SHORT).show();
            }
            else {
                textViewStatus.setText("You won! You Nutz!");
            }

        }

        @Override
        public void afterTextChanged(Editable editable) {

        }
    });

}

@Override
protected void onStop() {
    super.onStop();
}

@Override
protected void onDestroy() {
    super.onDestroy();
}
}

调试后我得到了这个：

E/AndroidRuntime: 致命异常: main 进程：com.example.user.ggame，PID：3291 java.lang.NumberFormatException：对于输入字符串：“” 在 java.lang.Integer.parseInt(Integer.java:620) 在 java.lang.Integer.parseInt(Integer.java:643) 在 com.example.user.ggame.MainActivity$2.onTextChanged(MainActivity.java:71) 在 android.widget.TextView.sendOnTextChanged(TextView.java:9359) 在 android.widget.TextView.handleTextChanged(TextView.java:9446) 在 android.widget.TextView$ChangeWatcher.onTextChanged(TextView.java:11904) 在 android.text.SpannableStringBuilder.sendTextChanged(SpannableStringBuilder.java:1252) 在 android.text.SpannableStringBuilder.replace(SpannableStringBuilder.java:573) 在 android.text.SpannableStringBuilder.delete(SpannableStringBuilder.java:229) 在 android.text.SpannableStringBuilder.delete(SpannableStringBuilder.java:227) 在 android.text.method.BaseKeyListener.backspaceOrForwardDelete(BaseKeyListener.java:370) 在 android.text.method.BaseKeyListener.backspace(BaseKeyListener.java:71) 在 android.text.method.BaseKeyListener.onKeyDown(BaseKeyListener.java:479) 在 android.text.method.NumberKeyListener.onKeyDown(NumberKeyListener.java:148) 在 android.widget.TextView.doKeyDown(TextView.java:7316) 在 android.widget.TextView.onKeyDown(TextView.java:7093) 在 android.view.KeyEvent.dispatch(KeyEvent.java:2688) 在 android.view.View.dispatchKeyEvent(View.java:11662) 在 android.view.ViewGroup.dispatchKeyEvent(ViewGroup.java:1827) 在 android.view.ViewGroup.dispatchKeyEvent(ViewGroup.java:1827) 在 android.view.ViewGroup.dispatchKeyEvent(ViewGroup.java:1827) 在 android.view.ViewGroup.dispatchKeyEvent(ViewGroup.java:1827) 在 android.view.ViewGroup.dispatchKeyEvent(ViewGroup.java:1827) 在 android.view.ViewGroup.dispatchKeyEvent(ViewGroup.java:1827) 在 android.view.ViewGroup.dispatchKeyEvent(ViewGroup.java:1827) 在 com.android.internal.policy.DecorView.superDispatchKeyEvent(DecorView.java:437) 在 com.android.internal.policy.PhoneWindow.superDispatchKeyEvent(PhoneWindow.java:1818) 在 android.app.Activity.dispatchKeyEvent(Activity.java:3252) 在 android.support.v7.app.AppCompatActivity.dispatchKeyEvent(AppCompatActivity.java:534) 在 android.support.v7.view.WindowCallbackWrapper.dispatchKeyEvent(WindowCallbackWrapper.java:58) 在 android.support.v7.app.AppCompatDelegateImplBase$AppCompatWindowCallbackBase.dispatchKeyEvent(AppCompatDelegateImplBase.java:316) 在 com.android.internal.policy.DecorView.dispatchKeyEvent(DecorView.java:351) 在 android.view.ViewRootImpl$ViewPostImeInputStage.processKeyEvent(ViewRootImpl.java:4714) 在 android.view.ViewRootImpl$ViewPostImeInputStage.onProcess(ViewRootImpl.java:4586) 在 android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:4128) 在 android.view.ViewRootImpl$InputStage.onDeliverToNext(ViewRootImpl.java:4181) 在 android.view.ViewRootImpl$InputStage.forward(ViewRootImpl.java:4147) 在 android.view.ViewRootImpl$AsyncInputStage.forward(ViewRootImpl.java:4274) 在 android.view.ViewRootImpl$InputStage.apply(ViewRootImpl.java:4155) 在 android.view.ViewRootImpl$AsyncInputStage.apply(ViewRootImpl.java:4331) 在 android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:4128) 在 android.view.ViewRootImpl$InputStage.onDeliverToNext(ViewRootImpl.java:4181) 在 android.view.ViewRootImpl$InputStage.forward(ViewRootImpl.java:4147) 在 android.view.ViewRootImpl$InputStage.apply(ViewRootImpl.java:4155) 在 android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:4128) 在 android.view.ViewRootImpl$InputStage.onDeliverToNext(ViewRootImpl.java:4181) 在 android.view.ViewRootImpl$InputStage.forward(ViewRootImpl.java:4147) 在 android.view.ViewRootImpl$AsyncInputStage.forward(ViewRootImpl.java:4307) 在 android.view.ViewRootImpl$ImeInputStage.onFinishedInputEvent(ViewRootImpl.java:4468) 在 android.view.inputmethod.InputMethodManager$PendingEvent.run(InputMethodManager.java:2435) 在 android.view.inputmethod.InputMethodManager.invokeFinishedInputEventCallback(InputMethodManager.java:1998) E/AndroidRuntime：在 android.view.inputmethod.InputMethodManager.finishedInputEvent(InputMethodManager.java:1989) 在 android.view.inputmethod.InputMethodManager$ImeInputEventSender.onInputEventFinished(InputMethodManager.java:2412) 在 android.view.InputEventSender.dispatchInputEventFinished(InputEventSender.java:141) 在 android.os.MessageQueue.nativePollOnce（本机方法） 在 android.os.MessageQueue.next(MessageQueue.java:325) 在 android.os.Looper.loop(Looper.java:142) 在 android.app.ActivityThread.main(ActivityThread.java:6541) 在 java.lang.reflect.Method.invoke（本机方法） 在 com.android.internal.os.Zygote$MethodAndArgsCaller.run(Zygote.java:240) 在 com.android.internal.os.ZygoteInit.main(ZygoteInit.java:767)

Answer 1

您的问题在这一行：

 String StringEditNum= editTextNum.getText().toString();
 int EditNum = Integer.parseInt(StringEditNum);

在清除5 时，StringEditNum 的值将是空字符串，您无法解析空字符串，因此它会崩溃

尝试添加这个：

String StringEditNum= editTextNum.getText().toString();
int EditNum = 0;
if(!StringEditNum.equals("")){
   EditNum = Integer.parseInt(StringEditNum);
}

Answer 2

试试下面的代码

   Random random = new Random();
   int RanNum = random.nextInt(MaxNumber-MinNumber)+MinNumber;
   String StringEditNum= editTextNum.getText().toString();
    if(!StringEditNum.equals("")){
        int EditNum = Integer.parseInt(StringEditNum);
        if (EditNum >RanNum){
            textViewStatus.setText("Enter Higher Number");
        }else if(EditNum <RanNum){
            textViewStatus.setText("Enter Lower Numer!");
        }else {
            textViewStatus.setText("You won! You Nutz!");
        }
    } else{
            Toast.makeText(MainActivity.this,"Try again!",Toast.LENGTH_SHORT).show();
        }

Answer 3

检查下面的代码。

editTextNum.addTextChangedListener(new TextWatcher() {
    @Override
    public void beforeTextChanged(CharSequence charSequence, int i, int i1, int i2) {

    }

    @Override
    public void onTextChanged(CharSequence charSequence, int i, int i1, int i2) {

      if(editTextNum.getText().toString().length() > 0)
      {
        Random random = new Random();
        int RanNum = random.nextInt(MaxNumber-MinNumber)+MinNumber;
        String StringEditNum= editTextNum.getText().toString();
        int EditNum = Integer.parseInt(StringEditNum);
        if (EditNum >RanNum){
            textViewStatus.setText("Enter Higher Number");
        }
        else if(EditNum <RanNum){
            textViewStatus.setText("Enter Lower Numer!");
        }
        else if (StringEditNum.equals("")){
            Toast.makeText(MainActivity.this,"Error!",Toast.LENGTH_SHORT).show();
        }
        else {
            textViewStatus.setText("You won! You Nutz!");
        }
      }
    }

    @Override
    public void afterTextChanged(Editable editable) {

    }
});

Answer 4

试试这个

1. 这将产生java.lang.IllegalArgumentException: n <= 0: 0，因为bound 应该是random.nextInt(bound) 0

      Random random = new Random();
      int RanNum = random.nextInt(MaxNumber-MinNumber)+MinNumber;
   
      try this
   
       Random random = new Random();
       int RanNum = random.nextInt((MaxNumber-MinNumber)+1);
   

2.String转换为整数时不能为null

    @Override
    public void onTextChanged(CharSequence charSequence, int i, int i1, int i2) {

        Random random = new Random();
        int RanNum = random.nextInt((MaxNumber-MinNumber)+1);
        String StringEditNum= editTextNum.getText().toString();
            if (!TextUtils.isEmpty(editTextNum.getText().toString()))
            {
                int EditNum = Integer.parseInt(StringEditNum);
                if (EditNum >RanNum){
                    textViewStatus.setText("Enter Higher Number");
                }
                else if(EditNum <RanNum){
                    textViewStatus.setText("Enter Lower Numer!");


                }
                else if (StringEditNum.equals("")){
                    Toast.makeText(MainActivity.this,"Error!",Toast.LENGTH_SHORT).show();
                }
                else {
                    textViewStatus.setText("You won! You Nutz!");
                }
            }else {

            }            

    }

Answer 5

在将其转换为 int

之前检查 StringEditNum 不为空或为空

    if(!StringEditNum.equalsIgnoreCase("")){

            int EditNum = Integer.parseInt(StringEditNum);

    }

Answer 6

问题是您正在使用 textWatcher 侦听器，并且每当您编写/删除某些内容时，都会调用此侦听器。现在，当你写数字 50 时，你写 5 和 0。然后当你删除它时，你首先删除 0，留下 5。在这种情况下，下面的行是好的

int EditNum = Integer.parseInt(StringEditNum);

但是当你删除 5 时，StringEditNum 变为 "" 并且上面的行会导致 java.lang.NumberFormatException。所以请检查下面的代码以使其完美运行

import java.util.Random;

public class MainActivity extends AppCompatActivity {
TextView textViewChoice, textViewStatus;
EditText editTextNum ;

Button buttonSetting;
SharedPreferences preferences;

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

textViewChoice = (TextView) findViewById(R.id.textViewChoice);
textViewStatus =(TextView) findViewById(R.id.textviewStatus);
editTextNum = (EditText) findViewById(R.id.edittextGuess);

buttonSetting =(Button) findViewById(R.id.buttonSetting);
preferences = getSharedPreferences("LIMITS",MODE_PRIVATE);




  buttonSetting.setOnClickListener(new View.OnClickListener() {
    @Override
    public void onClick(View view) {
        Intent intent = new Intent(MainActivity.this,        SecondaryActivity.class);
        startActivity(intent);
    }
});
}

@Override
protected void onStart() {
super.onStart();
final int MinNumber = preferences.getInt("Seekbar Min", 0);
final int MaxNumber = preferences.getInt("Seekbar Max", 0);
textViewChoice.setText("" + MinNumber + "-" + MaxNumber);

editTextNum.addTextChangedListener(new TextWatcher() {
    @Override
    public void beforeTextChanged(CharSequence charSequence, int i, int i1, int i2) {

    }

    @Override
    public void onTextChanged(CharSequence charSequence, int i, int i1, int i2) {
        Random random = new Random();
        int RanNum = random.nextInt(MaxNumber-MinNumber)+MinNumber;
        String StringEditNum= editTextNum.getText().toString();
        if(!StringEditNum.equals("")){
        int EditNum = Integer.parseInt(StringEditNum);
        if (EditNum >RanNum){
            textViewStatus.setText("Enter Higher Number");
        }
        else if(EditNum <RanNum){
            textViewStatus.setText("Enter Lower Numer!");


        }

        else {
            textViewStatus.setText("You won! You Nutz!");
        }
    }else{
          Toast.makeText(MainActivity.this,"Error!",Toast.LENGTH_SHORT).show();
    }
 }
    @Override
    public void afterTextChanged(Editable editable) {

    }
});

}

@Override
protected void onStop() {
super.onStop();
}

@Override
protected void onDestroy() {
super.onDestroy();
}
}