android - 即使指定字段为空也处理 StringIndexOutOfBoundsException

Question

当我按下 Android 应用程序的“提交”按钮时，我遇到了应用程序崩溃的情况。该应用程序负责发送输入的数据，将其作为事件添加到用户的日历中。仅当日期字段留空时应用程序才会崩溃。我注意到存储日期分割部分的变量有一个 java.lang.StringIndexOutOfBoundsException。我尝试注释日期字段数据输入，然后应用程序可以工作。

如果该字段留空，为什么会出现此异常？

如有任何修复，我们将不胜感激。

代码:

public void onClick(View view) {

        TextInputEditText textInputEditTextDate = (TextInputEditText) findViewById(R.id.date);
        EditText editTextTitle = (EditText) findViewById(R.id.title);
        EditText editTextDesc = (EditText) findViewById(R.id.desc);
        EditText editTextLocation = (EditText) findViewById(R.id.location);
        titl = editTextTitle.getText().toString();
        desc = editTextDesc.getText().toString();
        location = editTextLocation.getText().toString();
        date = textInputEditTextDate.getText().toString();
        day = Integer.parseInt(date.substring(0, 2));
        month = Integer.parseInt(date.substring(3, 5)) - 1;
        year = Integer.parseInt(date.substring(6, 10));

        if (titl.isEmpty() || desc.isEmpty() || location.isEmpty() || date.isEmpty()) {
            Toast.makeText(this, "No information", Toast.LENGTH_SHORT).show();
        } else {
            Intent calendarIntent = new Intent(Intent.ACTION_INSERT, CalendarContract.Events.CONTENT_URI);
            calendarIntent.putExtra(CalendarContract.Events.TITLE, titl);
            calendarIntent.putExtra(CalendarContract.Events.EVENT_LOCATION, location);
            calendarIntent.putExtra(CalendarContract.Events.DESCRIPTION, desc);
            calendarIntent.putExtra(CalendarContract.Reminders.METHOD, CalendarContract.Reminders.METHOD_DEFAULT);
            calendarIntent.putExtra(CalendarContract.Reminders.MINUTES, 1);
            calendarIntent.putExtra(String.valueOf(CalendarContract.Reminders.METHOD_ALERT), "1");
            GregorianCalendar date = new GregorianCalendar(year, month, day);
            calendarIntent.putExtra(CalendarContract.EXTRA_EVENT_BEGIN_TIME, date.getTimeInMillis());
            calendarIntent.putExtra(CalendarContract.EXTRA_EVENT_END_TIME, date.getTimeInMillis());
            startActivity(calendarIntent);
        }
    }

日志猫:

Process: com.cypherlabs.calendarapp, PID: 32057
    java.lang.IllegalStateException: Could not execute method for android:onClick
        at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:390)
        at android.view.View.performClick(View.java:7333)
        at android.widget.TextView.performClick(TextView.java:14160)
        at android.view.View.performClickInternal(View.java:7299)
        at android.view.View.access$3200(View.java:846)
        at android.view.View$PerformClick.run(View.java:27773)
        at android.os.Handler.handleCallback(Handler.java:873)
        at android.os.Handler.dispatchMessage(Handler.java:99)
        at android.os.Looper.loop(Looper.java:214)
        at android.app.ActivityThread.main(ActivityThread.java:6981)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1445)
     Caused by: java.lang.reflect.InvocationTargetException
        at java.lang.reflect.Method.invoke(Native Method)
        at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:385)
        at android.view.View.performClick(View.java:7333) 
        at android.widget.TextView.performClick(TextView.java:14160) 
        at android.view.View.performClickInternal(View.java:7299) 
        at android.view.View.access$3200(View.java:846) 
        at android.view.View$PerformClick.run(View.java:27773) 
        at android.os.Handler.handleCallback(Handler.java:873) 
        at android.os.Handler.dispatchMessage(Handler.java:99) 
        at android.os.Looper.loop(Looper.java:214) 
        at android.app.ActivityThread.main(ActivityThread.java:6981) 
        at java.lang.reflect.Method.invoke(Native Method) 
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493) 
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1445) 
     Caused by: java.lang.StringIndexOutOfBoundsException: length=0; index=2
        at java.lang.String.substring(String.java:2032)
        at com.cypherlabs.calendarapp.MainActivity.onClick(MainActivity.java:34)
        at java.lang.reflect.Method.invoke(Native Method) 
        at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:385) 
        at android.view.View.performClick(View.java:7333) 
        at android.widget.TextView.performClick(TextView.java:14160) 
        at android.view.View.performClickInternal(View.java:7299) 
        at android.view.View.access$3200(View.java:846) 
        at android.view.View$PerformClick.run(View.java:27773) 
        at android.os.Handler.handleCallback(Handler.java:873) 
        at android.os.Handler.dispatchMessage(Handler.java:99) 
        at android.os.Looper.loop(Looper.java:214) 
        at android.app.ActivityThread.main(ActivityThread.java:6981) 
        at java.lang.reflect.Method.invoke(Native Method) 
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493) 
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1445)

Answer 1

它正在按预期工作。你犯了一个错误。问题是你不能打电话subString() 在空字符串上。但是当你的字段为空时，根据代码它将尝试对 null 值调用 subString() 方法。

可以像下面这样解决。

if(date!=null && !date.isEmpty()){
     day = Integer.parseInt(date.substring(0, 2));
     month = Integer.parseInt(date.substring(3, 5)) - 1;
     year = Integer.parseInt(date.substring(6, 10));
}

请记住，每次需要用户输入时，所有方式都遵循此类验证。