classlib: add methods to java.util.Objects

classlib/src/main/java/org/teavm/classlib/java/util/TObjects.java

@@ -15,6 +15,7 @@
  */
 package org.teavm.classlib.java.util;
 
+import java.util.function.Supplier;
 import org.teavm.classlib.java.lang.TObject;
 
 public final class TObjects extends TObject {
@@ -52,6 +53,25 @@ public final class TObjects extends TObject {
         return obj;
     }
 
+    public static <T> T requireNonNull(T obj, Supplier<String> messageSupplier) {
+        if (obj == null) {
+            throw new NullPointerException(messageSupplier.get());
+        }
+        return obj;
+    }
+
+    public static <T> T requireNonNullElse(T obj, T defaultObj) {
+        return obj != null ? obj : requireNonNull(defaultObj);
+    }
+
+    public static <T> T requireNonNullElseGet(T obj, Supplier<? extends T> supplier) {
+        return obj != null ? obj : requireNonNull(supplier.get());
+    }
+
+    public static boolean isNull(Object obj) {
+        return obj == null;
+    }
+
     public static boolean nonNull(Object obj) {
         return obj != null;
     }
@@ -103,4 +123,25 @@ public final class TObjects extends TObject {
     public static int hash(Object... values) {
         return TArrays.hashCode(values);
     }
+
+    public static int checkIndex(int index, int length) {
+        if (index < 0 || index >= length) {
+            throw new IndexOutOfBoundsException();
+        }
+        return index;
+    }
+
+    public static int checkFromToIndex(int fromIndex, int toIndex, int length) {
+        if (fromIndex < 0 || fromIndex > toIndex || toIndex > length) {
+            throw new IndexOutOfBoundsException();
+        }
+        return fromIndex;
+    }
+
+    public static int checkFromIndexSize(int fromIndex, int size, int length) {
+        if (fromIndex < 0 || size < 0 || fromIndex + size > length) {
+            throw new IndexOutOfBoundsException();
+        }
+        return fromIndex;
+    }
 }