add ToStringHelper.omitEmptyValues(). Fixes #7415

RELNOTES=Add `ToStringHelper.omitEmptyValues()`.
PiperOrigin-RevId: 684168908

Author: kluever

android/guava-tests/test/com/google/common/base/ToStringHelperTest.java

@@ -20,8 +20,12 @@
 
 import com.google.common.annotations.GwtCompatible;
 import com.google.common.annotations.GwtIncompatible;
+import com.google.common.annotations.J2ktIncompatible;
 import com.google.common.collect.ImmutableMap;
+import java.nio.CharBuffer;
+import java.util.ArrayList;
 import java.util.Arrays;
+import java.util.HashMap;
 import java.util.Map;
 import junit.framework.TestCase;
 
@@ -316,6 +320,13 @@ public void testToStringOmitNullValues_oneField() {
     assertEquals("TestClass{}", toTest);
   }
 
+  @GwtIncompatible // Class names are obfuscated in GWT
+  public void testToStringOmitEmptyValues_oneField() {
+    String toTest =
+        MoreObjects.toStringHelper(new TestClass()).omitEmptyValues().add("field1", "").toString();
+    assertEquals("TestClass{}", toTest);
+  }
+
   @GwtIncompatible // Class names are obfuscated in GWT
   public void testToStringOmitNullValues_manyFieldsFirstNull() {
     String toTest =
@@ -328,6 +339,18 @@ public void testToStringOmitNullValues_manyFieldsFirstNull() {
     assertEquals("TestClass{field2=Googley, field3=World}", toTest);
   }
 
+  @GwtIncompatible // Class names are obfuscated in GWT
+  public void testToStringOmitEmptyValues_manyFieldsFirstEmpty() {
+    String toTest =
+        MoreObjects.toStringHelper(new TestClass())
+            .omitEmptyValues()
+            .add("field1", "")
+            .add("field2", "Googley")
+            .add("field3", "World")
+            .toString();
+    assertEquals("TestClass{field2=Googley, field3=World}", toTest);
+  }
+
   @GwtIncompatible // Class names are obfuscated in GWT
   public void testToStringOmitNullValues_manyFieldsOmitAfterNull() {
     String toTest =
@@ -340,6 +363,18 @@ public void testToStringOmitNullValues_manyFieldsOmitAfterNull() {
     assertEquals("TestClass{field2=Googley, field3=World}", toTest);
   }
 
+  @GwtIncompatible // Class names are obfuscated in GWT
+  public void testToStringOmitEmptyValues_manyFieldsOmitAfterEmpty() {
+    String toTest =
+        MoreObjects.toStringHelper(new TestClass())
+            .add("field1", "")
+            .add("field2", "Googley")
+            .add("field3", "World")
+            .omitEmptyValues()
+            .toString();
+    assertEquals("TestClass{field2=Googley, field3=World}", toTest);
+  }
+
   @GwtIncompatible // Class names are obfuscated in GWT
   public void testToStringOmitNullValues_manyFieldsLastNull() {
     String toTest =
@@ -352,6 +387,25 @@ public void testToStringOmitNullValues_manyFieldsLastNull() {
     assertEquals("TestClass{field1=Hello, field2=Googley}", toTest);
   }
 
+  @GwtIncompatible // Class names are obfuscated in GWT
+  public void testToStringOmitEmptyValues_manyFieldsLastEmpty() {
+    String toTest =
+        MoreObjects.toStringHelper(new TestClass())
+            .omitEmptyValues()
+            .add("field1", "Hello")
+            .add("field2", "Googley")
+            .add("field3", "")
+            .toString();
+    assertEquals("TestClass{field1=Hello, field2=Googley}", toTest);
+  }
+
+  @GwtIncompatible // Class names are obfuscated in GWT
+  public void testToStringOmitNullValues_oneValue() {
+    String toTest =
+        MoreObjects.toStringHelper(new TestClass()).omitEmptyValues().addValue("").toString();
+    assertEquals("TestClass{}", toTest);
+  }
+
   @GwtIncompatible // Class names are obfuscated in GWT
   public void testToStringOmitEmptyValues_oneValue() {
     String toTest =
@@ -371,6 +425,18 @@ public void testToStringOmitNullValues_manyValuesFirstNull() {
     assertEquals("TestClass{Googley, World}", toTest);
   }
 
+  @GwtIncompatible // Class names are obfuscated in GWT
+  public void testToStringOmitEmptyValues_manyValuesFirstEmpty() {
+    String toTest =
+        MoreObjects.toStringHelper(new TestClass())
+            .omitEmptyValues()
+            .addValue("")
+            .addValue("Googley")
+            .addValue("World")
+            .toString();
+    assertEquals("TestClass{Googley, World}", toTest);
+  }
+
   @GwtIncompatible // Class names are obfuscated in GWT
   public void testToStringOmitNullValues_manyValuesLastNull() {
     String toTest =
@@ -383,6 +449,18 @@ public void testToStringOmitNullValues_manyValuesLastNull() {
     assertEquals("TestClass{Hello, Googley}", toTest);
   }
 
+  @GwtIncompatible // Class names are obfuscated in GWT
+  public void testToStringOmitEmptyValues_manyValuesLastEmpty() {
+    String toTest =
+        MoreObjects.toStringHelper(new TestClass())
+            .omitEmptyValues()
+            .addValue("Hello")
+            .addValue("Googley")
+            .addValue("")
+            .toString();
+    assertEquals("TestClass{Hello, Googley}", toTest);
+  }
+
   @GwtIncompatible // Class names are obfuscated in GWT
   public void testToStringOmitNullValues_differentOrder() {
     String expected = "TestClass{field1=Hello, field2=Googley, field3=World}";
@@ -404,6 +482,27 @@ public void testToStringOmitNullValues_differentOrder() {
     assertEquals(expected, toTest2);
   }
 
+  @GwtIncompatible // Class names are obfuscated in GWT
+  public void testToStringOmitEmptyValues_differentOrder() {
+    String expected = "TestClass{field1=Hello, field2=Googley, field3=World}";
+    String toTest1 =
+        MoreObjects.toStringHelper(new TestClass())
+            .omitEmptyValues()
+            .add("field1", "Hello")
+            .add("field2", "Googley")
+            .add("field3", "World")
+            .toString();
+    String toTest2 =
+        MoreObjects.toStringHelper(new TestClass())
+            .add("field1", "Hello")
+            .add("field2", "Googley")
+            .omitEmptyValues()
+            .add("field3", "World")
+            .toString();
+    assertEquals(expected, toTest1);
+    assertEquals(expected, toTest2);
+  }
+
   @GwtIncompatible // Class names are obfuscated in GWT
   public void testToStringOmitNullValues_canBeCalledManyTimes() {
     String toTest =
@@ -419,6 +518,64 @@ public void testToStringOmitNullValues_canBeCalledManyTimes() {
     assertEquals("TestClass{field1=Hello, field2=Googley, field3=World}", toTest);
   }
 
+  @GwtIncompatible // Class names are obfuscated in GWT
+  public void testToStringOmitEmptyValues_canBeCalledManyTimes() {
+    String toTest =
+        MoreObjects.toStringHelper(new TestClass())
+            .omitEmptyValues()
+            .omitEmptyValues()
+            .add("field1", "Hello")
+            .omitEmptyValues()
+            .add("field2", "Googley")
+            .omitEmptyValues()
+            .add("field3", "World")
+            .toString();
+    assertEquals("TestClass{field1=Hello, field2=Googley, field3=World}", toTest);
+  }
+
+  @GwtIncompatible // Class names are obfuscated in GWT
+  public void testToStringOmitEmptyValues_allEmptyTypes() {
+    String toTest =
+        MoreObjects.toStringHelper(new TestClass())
+            .omitEmptyValues()
+            // CharSequences
+            .add("field1", "")
+            .add("field2", new StringBuilder())
+            // nio CharBuffer (implements CharSequence) is tested separately below
+            // Collections and Maps
+            .add("field11", Arrays.asList("Hello"))
+            .add("field12", new ArrayList<>())
+            .add("field13", new HashMap<>())
+            // Optionals
+            .add("field26", Optional.of("World"))
+            .add("field27", Optional.absent())
+            // Arrays
+            .add("field31", new Object[] {"!!!"})
+            .add("field32", new boolean[0])
+            .add("field33", new byte[0])
+            .add("field34", new char[0])
+            .add("field35", new short[0])
+            .add("field36", new int[0])
+            .add("field37", new long[0])
+            .add("field38", new float[0])
+            .add("field39", new double[0])
+            .add("field40", new Object[0])
+            .toString();
+    assertEquals("TestClass{field11=[Hello], field26=Optional.of(World), field31=[!!!]}", toTest);
+  }
+
+  @J2ktIncompatible // J2kt CharBuffer does not implement CharSequence so not recognized as empty
+  @GwtIncompatible // CharBuffer not available
+  public void testToStringOmitEmptyValues_charBuffer() {
+    String toTest =
+        MoreObjects.toStringHelper(new TestClass())
+            .omitEmptyValues()
+            .add("field1", "Hello")
+            .add("field2", CharBuffer.allocate(0))
+            .toString();
+    assertEquals("TestClass{field1=Hello}", toTest);
+  }
+
   public void testToStringHelperWithArrays() {
     String[] strings = {"hello", "world"};
     int[] ints = {2, 42};

android/guava/src/com/google/common/base/MoreObjects.java

@@ -169,6 +169,24 @@ public ToStringHelper omitNullValues() {
       return this;
     }
 
+    /**
+     * Configures the {@link ToStringHelper} so {@link #toString()} will ignore properties with
+     * empty values. The order of calling this method, relative to the {@code add()}/{@code
+     * addValue()} methods, is not significant.
+     *
+     * <p><b>Note:</b> in general, code should assume that the string form returned by
+     * `ToStringHelper` for a given object may change. In particular, the list of types which are
+     * checked for emptiness is subject to change. We currently check {@code CharSequence}s, {@code
+     * Collection}s, {@code Map}s, optionals (including Guava's), and arrays.
+     *
+     * @since NEXT
+     */
+    @CanIgnoreReturnValue
+    public ToStringHelper omitEmptyValues() {
+      omitEmptyValues = true;
+      return this;
+    }
+
     /**
      * Adds a name/value pair to the formatted output in {@code name=value} format. If {@code value}
      * is {@code null}, the string {@code "null"} is used, unless {@link #omitNullValues()} is