Cleanup: use .isEmpty() (except for CharSequence and StringBuilder as it requires SDK33).

src/androidTest/java/de/dennisguse/opentracks/settings/PreferencesUtilsTest.java

@@ -90,7 +90,7 @@ public class PreferencesUtilsTest {
 
         // then
         assertEquals(1, recordingLayouts.size());
-        assertTrue(recordingLayouts.get(0).getFields().size() > 0);
+        assertFalse(recordingLayouts.get(0).getFields().isEmpty());
         assertEquals(recordingLayouts.get(0).getName(), context.getString(R.string.stats_custom_layout_default_layout));
         assertTrue(recordingLayouts.get(0).getFields().stream().anyMatch(DataField::isVisible));
     }
@@ -107,7 +107,7 @@ public class PreferencesUtilsTest {
         RecordingLayout recordingLayout = PreferencesUtils.getCustomLayout();
 
         // then
-        assertTrue(recordingLayout.getFields().size() > 0);
+        assertFalse(recordingLayout.getFields().isEmpty());
         assertEquals(recordingLayout.getName(), context.getString(R.string.stats_custom_layout_default_layout));
         assertTrue(recordingLayout.getFields().stream().anyMatch(DataField::isVisible));
     }

src/main/java/de/dennisguse/opentracks/chart/ChartView.java

@@ -880,7 +880,7 @@ public class ChartView extends View {
                 break;
             }
         }
-        if (firstChartValueSeries != null && chartPoints.size() > 0) {
+        if (firstChartValueSeries != null && !chartPoints.isEmpty()) {
             int dx = getX(maxX) - pointer.getIntrinsicWidth() / 2;
             double value = firstChartValueSeries.extractDataFromChartPoint(last);
             int dy = getY(firstChartValueSeries, value) - pointer.getIntrinsicHeight();

src/main/java/de/dennisguse/opentracks/share/DescriptionGenerator.java

@@ -88,7 +88,7 @@ public class DescriptionGenerator {
      * @param lineBreak the line break
      */
     private void writeString(String text, StringBuilder builder, int resId, String lineBreak) {
-        if (text == null || text.length() == 0) {
+        if (text == null || text.isEmpty()) {
             text = context.getString(R.string.value_unknown);
         }
         builder.append(context.getString(resId, text));

src/main/java/de/dennisguse/opentracks/ui/util/ListItemUtils.java

@@ -49,13 +49,13 @@ public class ListItemUtils {
      */
     private static String getTimeDistance(String totalTime, String totalDistance) {
         StringBuilder builder = new StringBuilder();
-        if (totalTime != null && totalTime.length() != 0) {
+        if (totalTime != null && !totalTime.isEmpty()) {
             if (builder.length() != 0) {
                 builder.append(" ‧ ");
             }
             builder.append(totalTime);
         }
-        if (totalDistance != null && totalDistance.length() != 0) {
+        if (totalDistance != null && !totalDistance.isEmpty()) {
             if (builder.length() != 0) {
                 builder.append(" ");
             }