Java 不同活动中的项目未折叠
我正在尝试创建一个preferences活动,但由于某些原因,我的Switch控件没有按预期的方式运行。每当我导航到SettingsActivity时,它可以防止所需的ITM崩溃+我的应用程序崩溃。我真的不明白,当组件已经明确声明时,为什么会发生这种情况。以下是我的代码第2页和第3页的代码被省略,以减少我问题中的混乱: 活动_page1.xml activity_settings.xml 当前结果 预期结果 您没有将squareSwitch附加到任何UI组件。将您的SettingsActivity.java更新为以下内容:Java 不同活动中的项目未折叠,java,android,xml,android-preferences,android-switch,Java,Android,Xml,Android Preferences,Android Switch,我正在尝试创建一个preferences活动,但由于某些原因,我的Switch控件没有按预期的方式运行。每当我导航到SettingsActivity时,它可以防止所需的ITM崩溃+我的应用程序崩溃。我真的不明白,当组件已经明确声明时,为什么会发生这种情况。以下是我的代码第2页和第3页的代码被省略,以减少我问题中的混乱: 活动_page1.xml activity_settings.xml 当前结果 预期结果 您没有将squareSwitch附加到任何UI组件。将您的SettingsActiv
public class SettingsActivity extends AppCompatActivity implements CompoundButton.OnCheckedChangeListener {
boolean squareState;
SwitchCompat squareSwitch;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_settings);
squareSwitch = (SwitchCompat)findViewById(R.id.square_switch); //add this line
squareSwitch.setOnCheckedChangeListener(this); //Also add this
}
@Override
public void onResume(){
super.onResume();
loadPreferences();
displaySettings();
}
public void loadPreferences(){
SharedPreferences pref = getSharedPreferences("settings", AppCompatActivity.MODE_PRIVATE);
squareState = pref.getBoolean("square_state", true);
}
public void displaySettings(){
squareSwitch.setChecked(squareState);
}
@Override
public void onPause(){
super.onPause();
savePreferences();
}
private void savePreferences(){
SharedPreferences pref = getSharedPreferences("settings", AppCompatActivity.MODE_PRIVATE);
SharedPreferences.Editor editor = pref.edit();
editor.putBoolean("square_state", squareState);
editor.apply();
}
@Override
public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
int id = buttonView.getId();
switch(id){
case R.id.square_switch:
squareState = isChecked;
break;
}
}
此外,您不需要实现CompoundButton.OnCheckedChangeListener和override onCheckedChanged in Page1Activity,您可能希望从中删除这些内容。您需要强制转换,点击alt+enter,它将显示强制转换的建议。还更新了答案。你知道如何解决其他问题吗?由于缺少教程,几个月来我一直在努力解决这个问题:
public class Page1Activity extends AppCompatActivity {
boolean squareState;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_page1);
}
@Override
public void onResume(){
super.onResume();
loadPreferences();
displaySettings();
}
public void loadPreferences(){
SharedPreferences pref = getSharedPreferences("settings", AppCompatActivity.MODE_PRIVATE);
squareState = pref.getBoolean("square_state", true);
}
public void displaySettings() {
if (squareState) {
findViewById(R.id.blue_square).setVisibility(View.VISIBLE);
} else {
findViewById(R.id.blue_square).setVisibility(View.GONE);
}
}
}
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context="com.packagename.settingsapp.SettingsActivity">
<android.support.v7.widget.SwitchCompat
android:id="@+id/square_switch"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:checked="true"
android:layout_margin="20dp"
android:text="Show squares"
style="@android:style/TextAppearance.Large" />
<android.support.v7.widget.SwitchCompat
android:id="@+id/circle_switch"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:checked="true"
android:layout_margin="20dp"
android:text="Show circles"
style="@android:style/TextAppearance.Large"
android:layout_below="@id/square_switch"/>
<android.support.v7.widget.SwitchCompat
android:id="@+id/rectangle_switch"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:checked="true"
android:layout_margin="20dp"
android:text="Show rectangles"
style="@android:style/TextAppearance.Large"
android:layout_below="@id/circle_switch"/>
</RelativeLayout>
public class SettingsActivity extends AppCompatActivity {
boolean squareState;
SwitchCompat squareSwitch;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_settings);
}
@Override
public void onResume(){
super.onResume();
loadPreferences();
displaySettings();
}
public void loadPreferences(){
SharedPreferences pref = getSharedPreferences("settings", AppCompatActivity.MODE_PRIVATE);
squareState = pref.getBoolean("square_state", true);
}
public void displaySettings(){
squareSwitch.setChecked(squareState);
}
@Override
public void onPause(){
super.onPause();
savePreferences();
}
private void savePreferences(){
SharedPreferences pref = getSharedPreferences("settings", AppCompatActivity.MODE_PRIVATE);
SharedPreferences.Editor editor = pref.edit();
editor.putBoolean("square_state", squareState);
editor.apply();
}
@Override
public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
int id = buttonView.getId();
switch(id){
case R.id.square_switch:
squareState = isChecked;
break;
}
}
}
public class SettingsActivity extends AppCompatActivity implements CompoundButton.OnCheckedChangeListener {
boolean squareState;
SwitchCompat squareSwitch;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_settings);
squareSwitch = (SwitchCompat)findViewById(R.id.square_switch); //add this line
squareSwitch.setOnCheckedChangeListener(this); //Also add this
}
@Override
public void onResume(){
super.onResume();
loadPreferences();
displaySettings();
}
public void loadPreferences(){
SharedPreferences pref = getSharedPreferences("settings", AppCompatActivity.MODE_PRIVATE);
squareState = pref.getBoolean("square_state", true);
}
public void displaySettings(){
squareSwitch.setChecked(squareState);
}
@Override
public void onPause(){
super.onPause();
savePreferences();
}
private void savePreferences(){
SharedPreferences pref = getSharedPreferences("settings", AppCompatActivity.MODE_PRIVATE);
SharedPreferences.Editor editor = pref.edit();
editor.putBoolean("square_state", squareState);
editor.apply();
}
@Override
public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
int id = buttonView.getId();
switch(id){
case R.id.square_switch:
squareState = isChecked;
break;
}
}