我试图更新是否不是用户的共享偏好已经检查一箱不再显示欢迎屏幕。我访问我的共享偏好我的onClick侦听器的按钮。我得到一个空指针异常,我不知道如何解决它?的NullPointerException在按钮SharedPreferences ONCLICK
这里是我的代码....
public class WelcomeScreenActivity extends Activity {
SharedPreferences mPrefs;
final String welcomeScreenShownPref = "welcomeScreenShown";
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.welcomescreen);
final Button button = (Button) findViewById(R.id.welcomecontinue);
button.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
CheckBox cb = (CheckBox) findViewById(R.id.welcomecheckbox);
if(cb.isChecked()){
SharedPreferences.Editor editor = mPrefs.edit();
editor.putBoolean(welcomeScreenShownPref, true);
editor.commit(); // Very important to save the preference
Intent intent = new Intent(WelcomeScreenActivity.this, MainActivity.class);
startActivity(intent);
} else if(!cb.isChecked()){
SharedPreferences.Editor editor = mPrefs.edit();
editor.putBoolean(welcomeScreenShownPref, false);
editor.commit(); // Very important to save the preference
Intent intent = new Intent(WelcomeScreenActivity.this, MainActivity.class);
startActivity(intent);
}
}
});
}
}
任何人都可以提供一些线索到这个?
它看起来不像你曾经在那个包含的例子中设置mPrefs。 –
在什么方面是例外? –