Android studio android studio java.lang.NullPointerException
所以我正在开发一个需要在sd卡中写入的应用程序,当我尝试在文件中写入时,它会显示:Android studio android studio java.lang.NullPointerException,android-studio,Android Studio,所以我正在开发一个需要在sd卡中写入的应用程序,当我尝试在文件中写入时,它会显示:java.lang.NullPointerException 这是我的密码: public void goWrite() { File sdPath = Environment.getExternalStorageDirectory(); sdPath = new File(sdPath.getAbsolutePath() + "/" + DIR); sdPath.mkdir();
java.lang.NullPointerException
这是我的密码:
public void goWrite() {
File sdPath = Environment.getExternalStorageDirectory();
sdPath = new File(sdPath.getAbsolutePath() + "/" + DIR);
sdPath.mkdir();
Toast.makeText(this ,"" + sdPath ,Toast.LENGTH_LONG).show();
File sdFile = new File(sdPath ,filename);
try {
BufferedWriter bw = new BufferedWriter(new FileWriter(sdFile));
bw.write("Correct answers - " + correct + "\nincorrect answers - " + incorrect);
bw.close();
} catch (IOException e) {
e.printStackTrace();
}
}
这是我的舱单
我需要做什么?
感谢您的帮助:D在goWrite方法中。。。它没有确切说明NPE在哪里logcat应该包括callstack(带有行号)…Oops没有注意到这一点,问题在于sdFile声明行
<application
android:allowBackup="true"
android:icon="@mipmap/ic_launcher"
android:label="@string/app_name"
android:theme="@style/AppTheme" >
<activity
android:name=".indentification"
android:label="@string/app_name" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<activity
android:name=".trivia"
android:label="@string/title_activity_indentification" >
</activity>
<activity
android:name=".Summary"
android:label="@string/title_activity_summary" >
</activity>
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"></uses-permission>
</application>