boolean checked = Settings.System.getInt(context.getApplicationContext().getContentResolver(), "auto_call_record", 0) == 1;这个报空指针异常了，如何判空

可以使用以下方式进行判空：

if(context != null && context.getApplicationContext() != null){
    boolean checked = Settings.System.getInt(context.getApplicationContext().getContentResolver(), "auto_call_record", 0) == 1;
    // 进行后续操作
} else {
    // 执行异常处理
}

这里使用了两个判空条件，保证了 context 和 context.getApplicationContext() 不为 null 才会执行后续操作，避免了空指针异常的出现。

相关问题

fun subscribeWidgetMenuState(){ context.contentResolver.registerContentObserver( Settings.Secure.getUriFor("widget_menu_state"), true, object : ContentObserver(Handler()) { override fun onChange(selfChange: Boolean) { val widgetMenuState = Settings.Secure.getInt(contentResolver, "widget_menu_state") val widgetMenuXPosition = Settings.Secure.getInt(contentResolver, "widget_menu_x_position") Log.i(TAG, "onChange: widget_menu_state=$widgetMenuState, widget_menu_x_position=$widgetMenuXPosition") } }) } 将这段代码转换成java

以下是将 Kotlin 代码转换成 Java 代码后的实现：

public void subscribeWidgetMenuState() {
    getContentResolver().registerContentObserver(
            Settings.Secure.getUriFor("widget_menu_state"), 
            true, 
            new ContentObserver(new Handler()) {
                @Override
                public void onChange(boolean selfChange) {
                    int widgetMenuState = Settings.Secure.getInt(getContentResolver(), 
                            "widget_menu_state");
                    int widgetMenuXPosition = Settings.Secure.getInt(getContentResolver(), 
                            "widget_menu_x_position");
                    Log.i(TAG, "onChange: widget_menu_state=" + widgetMenuState 
                            + ", widget_menu_x_position=" + widgetMenuXPosition);
                }
            });
}

这段 Java 代码与 Kotlin 代码的功能是完全相同的，只是语法略有不同。

fun subscribeWidgetMenuPosition(){ contentResolver.registerContentObserver( Settings.Secure.getUriFor("wallpaper_menu_x_position"), true, object : ContentObserver(Handler()) { override fun onChange(selfChange: Boolean) { val widgetMenuState = Settings.Secure.getInt(contentResolver, "widget_menu_state") val widgetMenuXPosition = Settings.Secure.getInt(contentResolver, "widget_menu_x_position") Log.i(TAG, "onChange: widget_menu_state=$widgetMenuState, widget_menu_x_position=$widgetMenuXPosition") } }) } 转换为java代码

Here's the Java code equivalent to the given Kotlin code:

private void subscribeWidgetMenuPosition() {
    getContentResolver().registerContentObserver(
            Settings.Secure.getUriFor("wallpaper_menu_x_position"),
            true,
            new ContentObserver(new Handler()) {
                @Override
                public void onChange(boolean selfChange) {
                    int widgetMenuState = Settings.Secure.getInt(
                            getContentResolver(),
                            "widget_menu_state"
                    );
                    int widgetMenuXPosition = Settings.Secure.getInt(
                            getContentResolver(),
                            "widget_menu_x_position"
                    );
                    Log.i(TAG, "onChange: widget_menu_state=" + widgetMenuState +
                            ", widget_menu_x_position=" + widgetMenuXPosition);
                }
            }
    );
}