Java 如何为首选项中的seekBar设置onChangeListener?
如何设置首选项(pic)中seekbar的OnChangeListener?我已经尝试过此代码,但它将返回空指针异常: 优惠活动:Java 如何为首选项中的seekBar设置onChangeListener?,java,android,preferences,seekbar,preferenceactivity,Java,Android,Preferences,Seekbar,Preferenceactivity,如何设置首选项(pic)中seekbar的OnChangeListener?我已经尝试过此代码,但它将返回空指针异常: 优惠活动: import android.os.Bundle; import android.preference.Preference; import android.preference.PreferenceActivity; import android.widget.SeekBar; public class peferences extends Preference
import android.os.Bundle;
import android.preference.Preference;
import android.preference.PreferenceActivity;
import android.widget.SeekBar;
public class peferences extends PreferenceActivity {
private SeekBar SensitivitySeekBar;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
addPreferencesFromResource(R.xml.preferences);
SensitivitySeekBar = (SeekBar)findViewById(R.id.SeekBar2);
SensitivitySeekBar.setOnSeekBarChangeListener(new SeekBar.OnSeekBarChangeListener() {
public void onStopTrackingTouch(SeekBar seekBar) {
// TODO Auto-generated method stub
}
public void onStartTrackingTouch(SeekBar seekBar) {
// TODO Auto-generated method stub
}
public void onProgressChanged(SeekBar seekBar, int progress,
boolean fromUser) {
// TODO Auto-generated method stub
}
});
}
Preferences.xml:
<PreferenceScreen xmlns:android="http://schemas.android.com/apk/res/android">
<PreferenceCategory
android:title="@string/pref_accelerometer_title"
android:key="preference_accelerometer" >
<CheckBoxPreference
android:key="pref_key_x_axis"
android:summary="@string/preference_x_axis_summary"
android:title="Use x-axis"
android:defaultValue="true" android:order="1" android:enabled="true"/>
<CheckBoxPreference
android:title="Use y-axis"
android:key="pref_key_y_axis"
android:summary="@string/preference_y_axis_summary"
android:order="2"
android:enabled="true"
android:defaultValue="true"/>
<CheckBoxPreference
android:summary="@string/preference_z_axis_summary"
android:title="Use z-axis"
android:key="pref_key_z_axis"
android:order="3"
android:enabled="true"
android:defaultValue="true"/>
<CheckBoxPreference
android:title="Accelerometer value"
android:key="pref_accelerometer_value"
android:summary="@string/preference_show_accelerometer_value"/>
<Preference
android:layout="@layout/seekbar"
android:order="4"
android:key="seekbar"/>
</PreferenceCategory>
</PreferenceScreen>
我遇到了同样的NPE问题,通过定义我的
SeekbarPreference
并在onbindialogview
中注册侦听器,我成功地解决了这个问题。代码如下:
public class SeekbarPreference extends DialogPreference implements
OnSeekBarChangeListener {
private SeekBar mSeekbar;
@Override
protected void onBindDialogView(View view) {
super.onBindDialogView(view);
mSeekbar = (SeekBar) view.findViewById(R.id.sb_text_size);
mSeekbar.setOnSeekBarChangeListener(this);
}
public SeekbarPreference(Context context, AttributeSet attrs) {
super(context, attrs);
this.setDialogLayoutResource(R.layout.setting_textsize_seekbar);
}
@Override
protected void onDialogClosed(boolean positiveResult) {
if (positiveResult) {
// save to SharedPrefs, etc
}
}
@Override
public void onProgressChanged(SeekBar seekbar, int progress, boolean fromUser) {
}
@Override
public void onStartTrackingTouch(SeekBar seekBar) {
}
@Override
public void onStopTrackingTouch(SeekBar seekBar) {
}
}
下面是我的preference.xml:
<PreferenceCategory
<com.flounder.xeniaNote.view.SeekbarPreference
android:dialogLayout="@layout/setting_textsize_seekbar"
android:key="@string/pref_text_size_key"
android:title="@string/pref_text_size" />
...
</PreferenceCategory>
我遇到了同样的NPE问题,我通过定义我的SeekbarPreference
并在onBindDialogView
中注册侦听器来解决这个问题。代码如下:
public class SeekbarPreference extends DialogPreference implements
OnSeekBarChangeListener {
private SeekBar mSeekbar;
@Override
protected void onBindDialogView(View view) {
super.onBindDialogView(view);
mSeekbar = (SeekBar) view.findViewById(R.id.sb_text_size);
mSeekbar.setOnSeekBarChangeListener(this);
}
public SeekbarPreference(Context context, AttributeSet attrs) {
super(context, attrs);
this.setDialogLayoutResource(R.layout.setting_textsize_seekbar);
}
@Override
protected void onDialogClosed(boolean positiveResult) {
if (positiveResult) {
// save to SharedPrefs, etc
}
}
@Override
public void onProgressChanged(SeekBar seekbar, int progress, boolean fromUser) {
}
@Override
public void onStartTrackingTouch(SeekBar seekBar) {
}
@Override
public void onStopTrackingTouch(SeekBar seekBar) {
}
}
下面是我的preference.xml:
<PreferenceCategory
<com.flounder.xeniaNote.view.SeekbarPreference
android:dialogLayout="@layout/setting_textsize_seekbar"
android:key="@string/pref_text_size_key"
android:title="@string/pref_text_size" />
...
</PreferenceCategory>
这不是向首选项xml添加SeekBar
的方式。您将获得一个空指针,因为SeekBar实际上不存在于从xml创建的视图中。下面是一个如何实现的示例:这不是向首选项xml添加SeekBar
的方式。您将获得一个空指针,因为SeekBar实际上不存在于从xml创建的视图中。下面是一个如何实现的示例: