diff --git a/teavm-classlib/pom.xml b/teavm-classlib/pom.xml
index 2624f6ff9..2b09f1141 100644
--- a/teavm-classlib/pom.xml
+++ b/teavm-classlib/pom.xml
@@ -106,6 +106,7 @@
             <argument>java.math</argument>
             <argument>java.net</argument>
             <argument>java.nio</argument>
+            <argument>java.nio.charset</argument>
             <argument>java.text</argument>
             <argument>java.util</argument>
             <argument>java.util.logging</argument>
diff --git a/teavm-classlib/src/main/java/org/teavm/classlib/java/nio/charset/TCharset.java b/teavm-classlib/src/main/java/org/teavm/classlib/java/nio/charset/TCharset.java
index 26bc0c1ef..22ae9cad8 100644
--- a/teavm-classlib/src/main/java/org/teavm/classlib/java/nio/charset/TCharset.java
+++ b/teavm-classlib/src/main/java/org/teavm/classlib/java/nio/charset/TCharset.java
@@ -18,6 +18,9 @@ package org.teavm.classlib.java.nio.charset;
 import java.util.Collections;
 import java.util.HashSet;
 import java.util.Set;
+import org.teavm.classlib.java.nio.TByteBuffer;
+import org.teavm.classlib.java.nio.TCharBuffer;
+import org.teavm.classlib.java.nio.charset.impl.UTF8Charset;
 
 /**
  *
@@ -29,12 +32,54 @@ public abstract class TCharset implements Comparable<TCharset> {
     private Set<String> aliasSet;
 
     protected TCharset(String canonicalName, String[] aliases) {
+        checkCanonicalName(canonicalName);
+        for (String alias : aliases) {
+            checkCanonicalName(alias);
+        }
         this.canonicalName = canonicalName;
         this.aliases = aliases.clone();
     }
 
+    private static void checkCanonicalName(String name) {
+        if (name.isEmpty()) {
+            throw new TIllegalCharsetNameException(name);
+        }
+        if (!isValidCharsetStart(name.charAt(0))) {
+            throw new TIllegalCharsetNameException(name);
+        }
+        for (int i = 1; i < name.length(); ++i) {
+            char c = name.charAt(i);
+            switch (c) {
+                case '-':
+                case '+':
+                case '.':
+                case ':':
+                case '_':
+                    break;
+                default:
+                    if (!isValidCharsetStart(c)) {
+                        throw new TIllegalCharsetNameException(name);
+                    }
+                    break;
+            }
+        }
+    }
+
+    private static boolean isValidCharsetStart(char c) {
+        return c >= '0' && c <= '9' || c >= 'a' && c <= 'z' || c >= 'A' || c <= 'Z';
+    }
+
     public static TCharset forName(String charsetName) {
-        return null;
+        if (charsetName == null) {
+            throw new IllegalArgumentException("charsetName is null");
+        }
+        checkCanonicalName(charsetName);
+        switch (charsetName.toUpperCase()) {
+            case "UTF-8":
+                return new UTF8Charset();
+            default:
+                throw new TUnsupportedCharsetException(charsetName);
+        }
     }
 
     public final String name() {
@@ -56,6 +101,8 @@ public abstract class TCharset implements Comparable<TCharset> {
         return canonicalName;
     }
 
+    public abstract boolean contains(TCharset cs);
+
     public abstract TCharsetDecoder newDecoder();
 
     public abstract TCharsetEncoder newEncoder();
@@ -63,4 +110,35 @@ public abstract class TCharset implements Comparable<TCharset> {
     public boolean canEncode() {
         return true;
     }
+
+    public final TCharBuffer decode(TByteBuffer bb) {
+        try {
+            return newDecoder()
+                    .onMalformedInput(TCodingErrorAction.REPLACE)
+                    .onUnmappableCharacter(TCodingErrorAction.REPLACE)
+                    .decode(bb);
+        } catch (TCharacterCodingException e) {
+            throw new AssertionError("Should never been thrown", e);
+        }
+    }
+
+    public final TByteBuffer encode(TCharBuffer cb) {
+        try {
+            return newEncoder()
+                    .onMalformedInput(TCodingErrorAction.REPLACE)
+                    .onUnmappableCharacter(TCodingErrorAction.REPLACE)
+                    .encode(cb);
+        } catch (TCharacterCodingException e) {
+            throw new AssertionError("Should never been thrown", e);
+        }
+    }
+
+    public final TByteBuffer encode(String str) {
+        return encode(TCharBuffer.wrap(str));
+    }
+
+    @Override
+    public final int compareTo(TCharset that) {
+        return canonicalName.compareToIgnoreCase(that.canonicalName);
+    }
 }
diff --git a/teavm-classlib/src/main/java/org/teavm/classlib/java/nio/charset/TCharsetDecoder.java b/teavm-classlib/src/main/java/org/teavm/classlib/java/nio/charset/TCharsetDecoder.java
index e3587a204..3447037ca 100644
--- a/teavm-classlib/src/main/java/org/teavm/classlib/java/nio/charset/TCharsetDecoder.java
+++ b/teavm-classlib/src/main/java/org/teavm/classlib/java/nio/charset/TCharsetDecoder.java
@@ -15,10 +15,230 @@
  */
 package org.teavm.classlib.java.nio.charset;
 
+import java.util.Arrays;
+import org.teavm.classlib.java.nio.TByteBuffer;
+import org.teavm.classlib.java.nio.TCharBuffer;
+
 /**
  *
  * @author Alexey Andreev
  */
-public class TCharsetDecoder {
+public abstract class TCharsetDecoder {
+    private static final int INIT = 0;
+    private static final int IN_PROGRESS = 1;
+    private static final int END = 2;
+    private static final int FLUSH = 2;
+    private TCharset charset;
+    private float averageCharsPerByte;
+    private float maxCharsPerByte;
+    private String replacement = "?";
+    private TCodingErrorAction malformedAction = TCodingErrorAction.REPORT;
+    private TCodingErrorAction unmappableAction = TCodingErrorAction.REPORT;
+    private int state;
 
+    protected TCharsetDecoder(TCharset cs, float averageCharsPerByte, float maxCharsPerByte) {
+        if (averageCharsPerByte <= 0) {
+            throw new IllegalArgumentException("averageCharsPerByte must be positive. Actual value is " +
+                    averageCharsPerByte);
+        }
+        if (maxCharsPerByte <= 0) {
+            throw new IllegalArgumentException("maxCharsPerByte must be positive. Actual value is " +
+                    maxCharsPerByte);
+        }
+        this.charset = cs;
+        this.averageCharsPerByte = averageCharsPerByte;
+        this.maxCharsPerByte = maxCharsPerByte;
+    }
+
+    public final TCharset charset() {
+        return charset;
+    }
+
+    public final String replacement() {
+        return replacement;
+    }
+
+    public final TCharsetDecoder replaceWith(String newReplacement) {
+        if (newReplacement == null || newReplacement.isEmpty()) {
+            throw new IllegalArgumentException("New replacement is null or empty");
+        }
+        this.replacement = newReplacement;
+        implReplaceWith(newReplacement);
+        return this;
+    }
+
+    protected void implReplaceWith(@SuppressWarnings("unused") String newReplacement) {
+    }
+
+    public TCodingErrorAction malformedInputAction() {
+        return malformedAction;
+    }
+
+    public final TCharsetDecoder onMalformedInput(TCodingErrorAction newAction) {
+        if (newAction == null) {
+            throw new IllegalArgumentException("newAction must be non-null");
+        }
+        this.malformedAction = newAction;
+        implOnMalformedInput(newAction);
+        return this;
+    }
+
+    protected void implOnMalformedInput(@SuppressWarnings("unused") TCodingErrorAction newAction) {
+    }
+
+    public TCodingErrorAction unmappableCharacterAction() {
+        return unmappableAction;
+    }
+
+    public final TCharsetDecoder onUnmappableCharacter(TCodingErrorAction newAction) {
+        if (newAction == null) {
+            throw new IllegalArgumentException("newAction must be non-null");
+        }
+        this.unmappableAction = newAction;
+        implOnUnmappableCharacter(newAction);
+        return this;
+    }
+
+    protected void implOnUnmappableCharacter(@SuppressWarnings("unused") TCodingErrorAction newAction) {
+    }
+
+    public final float averageCharsPerByte() {
+        return averageCharsPerByte;
+    }
+
+    public final float maxCharsPerByte() {
+        return maxCharsPerByte;
+    }
+
+    public final TCoderResult decode(TByteBuffer in, TCharBuffer out, boolean endOfInput) {
+        if (state == END && !endOfInput || state == FLUSH) {
+            throw new IllegalStateException();
+        }
+        state = !endOfInput ? IN_PROGRESS : END;
+        while (true) {
+            TCoderResult result;
+            try {
+                result = decodeLoop(in, out);
+            } catch (RuntimeException e) {
+                throw new TCoderMalfunctionError(e);
+            }
+            if (result.isOverflow()) {
+                return result;
+            } else if (result.isUnderflow()) {
+                if (endOfInput) {
+                    state = END;
+                    return TCoderResult.malformedForLength(in.remaining());
+                }
+                return result;
+            } else if (result.isMalformed()) {
+                if (malformedAction == TCodingErrorAction.REPORT) {
+                    return result;
+                }
+                if (malformedAction == TCodingErrorAction.REPLACE) {
+                    if (out.remaining() < replacement.length()) {
+                        return TCoderResult.OVERFLOW;
+                    }
+                    out.put(replacement);
+                }
+                in.position(in.position() + result.length());
+            } else if (result.isUnmappable()) {
+                if (unmappableAction == TCodingErrorAction.REPORT) {
+                    return result;
+                }
+                if (unmappableAction == TCodingErrorAction.REPLACE) {
+                    if (out.remaining() < replacement.length()) {
+                        return TCoderResult.OVERFLOW;
+                    }
+                    out.put(replacement);
+                }
+                in.position(in.position() + result.length());
+            }
+        }
+    }
+
+    public final TCoderResult flush(TCharBuffer out) {
+        if (state != FLUSH && state != END) {
+            throw new IllegalStateException();
+        }
+        state = FLUSH;
+        return implFlush(out);
+    }
+
+    public final TCharsetDecoder reset() {
+        state = INIT;
+        implReset();
+        return this;
+    }
+
+    public final TCharBuffer decode(TByteBuffer in) throws TCharacterCodingException {
+        if (state != INIT && state != FLUSH) {
+            throw new IllegalStateException();
+        }
+        if (in.remaining() == 0) {
+            return TCharBuffer.allocate(0);
+        }
+        if (state != INIT) {
+            reset();
+        }
+
+        TCharBuffer out = TCharBuffer.allocate((int)(averageCharsPerByte * in.remaining()));
+        TCoderResult result;
+        while (true) {
+            result = decode(in, out, false);
+            if (result.isUnderflow()) {
+                break;
+            } else if (result.isOverflow()) {
+                out = expand(out);
+            }
+            if (result.isError()) {
+                result.throwException();
+            }
+        }
+
+        result = decode(in, out, true);
+        if (result.isError()) {
+            result.throwException();
+        }
+
+        while (true) {
+            result = flush(out);
+            if (result.isUnderflow()) {
+                break;
+            } else {
+                out = expand(out);
+            }
+        }
+
+        out.flip();
+        return out;
+    }
+
+    public boolean isAutoDetecting() {
+        return false;
+    }
+
+    public boolean isCharsetDetected() {
+        throw new UnsupportedOperationException();
+    }
+
+    public TCharset detectedCharset() {
+        throw new UnsupportedOperationException();
+    }
+
+    private TCharBuffer expand(TCharBuffer buffer) {
+        char[] array = buffer.array();
+        array = Arrays.copyOf(array, array.length * 2);
+        TCharBuffer result = TCharBuffer.wrap(array);
+        result.position(buffer.position());
+        return result;
+    }
+
+    protected abstract TCoderResult decodeLoop(TByteBuffer in, TCharBuffer out);
+
+    protected TCoderResult implFlush(@SuppressWarnings("unused") TCharBuffer out) {
+        return TCoderResult.UNDERFLOW;
+    }
+
+    protected void implReset() {
+    }
 }
diff --git a/teavm-classlib/src/main/java/org/teavm/classlib/java/nio/charset/TCharsetEncoder.java b/teavm-classlib/src/main/java/org/teavm/classlib/java/nio/charset/TCharsetEncoder.java
index f09f10d8f..65282e5eb 100644
--- a/teavm-classlib/src/main/java/org/teavm/classlib/java/nio/charset/TCharsetEncoder.java
+++ b/teavm-classlib/src/main/java/org/teavm/classlib/java/nio/charset/TCharsetEncoder.java
@@ -15,6 +15,7 @@
  */
 package org.teavm.classlib.java.nio.charset;
 
+import java.util.Arrays;
 import org.teavm.classlib.java.nio.TByteBuffer;
 import org.teavm.classlib.java.nio.TCharBuffer;
 
@@ -23,11 +24,11 @@ import org.teavm.classlib.java.nio.TCharBuffer;
  * @author Alexey Andreev
  */
 public abstract class TCharsetEncoder {
-    private static final int READY = 0;
+    private static final int READY = 4;
     private static final int ONGOING = 1;
     private static final int END = 2;
     private static final int FLUSH = 3;
-    private static final int INIT = 4;
+    private static final int INIT = 0;
     private TCharset charset;
     private byte[] replacement;
     private float averageBytesPerChar;
@@ -35,7 +36,6 @@ public abstract class TCharsetEncoder {
     private TCodingErrorAction malformedAction = TCodingErrorAction.REPORT;
     private TCodingErrorAction unmappableAction = TCodingErrorAction.REPORT;
     private int status;
-    private boolean finished;
 
     protected TCharsetEncoder(TCharset cs, float averageBytesPerChar, float maxBytesPerChar, byte[] replacement) {
         checkReplacement(replacement);
@@ -43,7 +43,6 @@ public abstract class TCharsetEncoder {
         this.replacement = replacement.clone();
         this.averageBytesPerChar = averageBytesPerChar;
         this.maxBytesPerChar = maxBytesPerChar;
-        status = INIT;
     }
 
     protected TCharsetEncoder(TCharset cs, float averageBytesPerChar, float maxBytesPerChar) {
@@ -115,25 +114,19 @@ public abstract class TCharsetEncoder {
     }
 
     public final TCoderResult encode(TCharBuffer in, TByteBuffer out, boolean endOfInput) {
-        if (status == READY && finished && !endOfInput) {
-            throw new IllegalStateException();
-        }
-
         if (status == FLUSH || !endOfInput && status == END) {
             throw new IllegalStateException();
         }
 
+        status = endOfInput ? END : ONGOING;
         TCoderResult result;
         while (true) {
             try {
                 result = encodeLoop(in, out);
-            } catch (TBufferOverflowException e) {
-                throw new TCoderMalfunctionError(e);
-            } catch (TBufferUnderflowException e) {
+            } catch (RuntimeException e) {
                 throw new TCoderMalfunctionError(e);
             }
-            if (result == TCoderResult.UNDERFLOW) {
-                status = endOfInput ? END : ONGOING;
+            if (result.isUnderflow()) {
                 if (endOfInput) {
                     int remaining = in.remaining();
                     if (remaining > 0) {
@@ -144,14 +137,10 @@ public abstract class TCharsetEncoder {
                 } else {
                     return result;
                 }
-            } else if (result == TCoderResult.OVERFLOW) {
-                status = endOfInput ? END : ONGOING;
+            } else if (result.isOverflow()) {
                 return result;
             }
-            TCodingErrorAction action = malformedAction;
-            if (result.isUnmappable()) {
-                action = unmappableAction;
-            }
+            TCodingErrorAction action = result.isUnmappable() ? unmappableAction : malformedAction;
             if (action == TCodingErrorAction.REPLACE) {
                 if (out.remaining() < replacement.length) {
                     return TCoderResult.OVERFLOW;
@@ -171,9 +160,9 @@ public abstract class TCharsetEncoder {
             return TByteBuffer.allocate(0);
         }
         reset();
-        int length = (int)(in.remaining() * averageBytesPerChar);
-        TByteBuffer output = TByteBuffer.allocate(length);
-        TCoderResult result = null;
+        TByteBuffer output = TByteBuffer.allocate((int)(in.remaining() * averageBytesPerChar));
+
+        TCoderResult result;
         while (true) {
             result = encode(in, output, false);
             if (result == TCoderResult.UNDERFLOW) {
@@ -182,31 +171,25 @@ public abstract class TCharsetEncoder {
                 output = allocateMore(output);
                 continue;
             }
-            checkCoderResult(result);
+            if (result.isError()) {
+                result.throwException();
+            }
         }
+
         result = encode(in, output, true);
-        checkCoderResult(result);
+        if (result.isError()) {
+            result.throwException();
+        }
 
         while (true) {
             result = flush(output);
-            if (result == TCoderResult.UNDERFLOW) {
-                output.flip();
+            if (result.isUnderflow()) {
                 break;
-            } else if (result == TCoderResult.OVERFLOW) {
+            } else if (result.isOverflow()) {
                 output = allocateMore(output);
-                continue;
             }
-            checkCoderResult(result);
-            output.flip();
-            if (result.isMalformed()) {
-                throw new TMalformedInputException(result.length());
-            } else if (result.isUnmappable()) {
-                throw new TUnmappableCharacterException(result.length());
-            }
-            break;
         }
-        status = READY;
-        finished = true;
+        output.flip();
         return output;
     }
 
@@ -249,21 +232,11 @@ public abstract class TCharsetEncoder {
         return implCanEncode(cb);
     }
 
-    private void checkCoderResult(TCoderResult result) throws TCharacterCodingException {
-        if (malformedAction == TCodingErrorAction.REPORT && result.isMalformed()) {
-            throw new TMalformedInputException(result.length());
-        } else if (unmappableAction == TCodingErrorAction.REPORT && result.isUnmappable()) {
-            throw new TUnmappableCharacterException(result.length());
-        }
-    }
-
-    private TByteBuffer allocateMore(TByteBuffer output) {
-        if (output.capacity() == 0) {
-            return TByteBuffer.allocate(1);
-        }
-        TByteBuffer result = TByteBuffer.allocate(output.capacity() * 2);
-        output.flip();
-        result.put(output);
+    private TByteBuffer allocateMore(TByteBuffer buffer) {
+        byte[] array = buffer.array();
+        array = Arrays.copyOf(array, array.length * 2);
+        TByteBuffer result = TByteBuffer.wrap(array);
+        result.position(buffer.position());
         return result;
     }
 
diff --git a/teavm-classlib/src/main/java/org/teavm/classlib/java/nio/charset/TIllegalCharsetNameException.java b/teavm-classlib/src/main/java/org/teavm/classlib/java/nio/charset/TIllegalCharsetNameException.java
new file mode 100644
index 000000000..8915fbcda
--- /dev/null
+++ b/teavm-classlib/src/main/java/org/teavm/classlib/java/nio/charset/TIllegalCharsetNameException.java
@@ -0,0 +1,33 @@
+/*
+ *  Copyright 2015 Alexey Andreev.
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License");
+ *  you may not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *
+ *       http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS,
+ *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ */
+package org.teavm.classlib.java.nio.charset;
+
+/**
+ *
+ * @author Alexey Andreev
+ */
+public class TIllegalCharsetNameException extends IllegalArgumentException {
+    private static final long serialVersionUID = -6848948447254188722L;
+    private String charsetName;
+
+    public TIllegalCharsetNameException(String charsetName) {
+        this.charsetName = charsetName;
+    }
+
+    public String getCharsetName() {
+        return charsetName;
+    }
+}
diff --git a/teavm-classlib/src/main/java/org/teavm/classlib/java/nio/charset/TUnsupportedCharsetException.java b/teavm-classlib/src/main/java/org/teavm/classlib/java/nio/charset/TUnsupportedCharsetException.java
new file mode 100644
index 000000000..a97fdeea8
--- /dev/null
+++ b/teavm-classlib/src/main/java/org/teavm/classlib/java/nio/charset/TUnsupportedCharsetException.java
@@ -0,0 +1,33 @@
+/*
+ *  Copyright 2015 Alexey Andreev.
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License");
+ *  you may not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *
+ *       http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS,
+ *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ */
+package org.teavm.classlib.java.nio.charset;
+
+/**
+ *
+ * @author Alexey Andreev
+ */
+public class TUnsupportedCharsetException extends IllegalArgumentException {
+    private static final long serialVersionUID = 2668607022458967777L;
+    private String charsetName;
+
+    public TUnsupportedCharsetException(String charsetName) {
+        this.charsetName = charsetName;
+    }
+
+    public String getCharsetName() {
+        return charsetName;
+    }
+}
diff --git a/teavm-classlib/src/main/java/org/teavm/classlib/java/nio/charset/impl/UTF8Charset.java b/teavm-classlib/src/main/java/org/teavm/classlib/java/nio/charset/impl/UTF8Charset.java
new file mode 100644
index 000000000..d9d8449d0
--- /dev/null
+++ b/teavm-classlib/src/main/java/org/teavm/classlib/java/nio/charset/impl/UTF8Charset.java
@@ -0,0 +1,45 @@
+/*
+ *  Copyright 2015 Alexey Andreev.
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License");
+ *  you may not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *
+ *       http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS,
+ *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ */
+package org.teavm.classlib.java.nio.charset.impl;
+
+import org.teavm.classlib.java.nio.charset.TCharset;
+import org.teavm.classlib.java.nio.charset.TCharsetDecoder;
+import org.teavm.classlib.java.nio.charset.TCharsetEncoder;
+
+/**
+ *
+ * @author Alexey Andreev
+ */
+public class UTF8Charset extends TCharset {
+    public UTF8Charset() {
+        super("UTF-8", new String[0]);
+    }
+
+    @Override
+    public boolean contains(TCharset cs) {
+        return cs == this;
+    }
+
+    @Override
+    public TCharsetDecoder newDecoder() {
+        return new UTF8Decoder(this);
+    }
+
+    @Override
+    public TCharsetEncoder newEncoder() {
+        return null;
+    }
+}
diff --git a/teavm-classlib/src/main/java/org/teavm/classlib/java/nio/charset/impl/UTF8Decoder.java b/teavm-classlib/src/main/java/org/teavm/classlib/java/nio/charset/impl/UTF8Decoder.java
new file mode 100644
index 000000000..b7c93bb17
--- /dev/null
+++ b/teavm-classlib/src/main/java/org/teavm/classlib/java/nio/charset/impl/UTF8Decoder.java
@@ -0,0 +1,83 @@
+/*
+ *  Copyright 2015 Alexey Andreev.
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License");
+ *  you may not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *
+ *       http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS,
+ *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ */
+package org.teavm.classlib.java.nio.charset.impl;
+
+import org.teavm.classlib.impl.charset.UTF16Helper;
+import org.teavm.classlib.java.nio.TByteBuffer;
+import org.teavm.classlib.java.nio.TCharBuffer;
+import org.teavm.classlib.java.nio.charset.TCharset;
+import org.teavm.classlib.java.nio.charset.TCharsetDecoder;
+import org.teavm.classlib.java.nio.charset.TCoderResult;
+
+/**
+ *
+ * @author Alexey Andreev
+ */
+public class UTF8Decoder extends TCharsetDecoder {
+    public UTF8Decoder(TCharset cs) {
+        super(cs, 1f / 3, 0.5f);
+    }
+
+    @Override
+    protected TCoderResult decodeLoop(TByteBuffer in, TCharBuffer out) {
+        while (true) {
+            if (in.remaining() < 4) {
+                return TCoderResult.UNDERFLOW;
+            }
+            if (!out.hasRemaining()) {
+                return TCoderResult.OVERFLOW;
+            }
+            int b = in.get() & 0xFF;
+            if ((b & 0x80) == 0) {
+                out.put((char)b);
+            } else if ((b & 0xE0) == 0xC0) {
+                if (!in.hasRemaining()) {
+                    in.position(in.position() - 1);
+                    return TCoderResult.UNDERFLOW;
+                }
+                out.put((char)(((b & 0x1F) << 6) | (in.get() & 0x3F)));
+            } else if ((b & 0xF0) == 0xE0) {
+                if (in.remaining() < 2) {
+                    in.position(in.position() - 1);
+                    return TCoderResult.UNDERFLOW;
+                }
+                byte b2 = in.get();
+                byte b3 = in.get();
+                char c = (char)(((b & 0x0F) << 12) | ((b2 & 0x3f) << 6) | (b3 & 0x3F));
+                if (Character.isSurrogate(c)) {
+                    in.position(in.position() - 2);
+                    return TCoderResult.malformedForLength(3);
+                }
+                out.put(c);
+            } else if ((b & 0xF8) == 0xF0) {
+                if (in.remaining() < 3) {
+                    in.position(in.position() - 1);
+                    return TCoderResult.UNDERFLOW;
+                }
+                if (out.remaining() < 3) {
+                    in.position(in.position() - 1);
+                    return TCoderResult.OVERFLOW;
+                }
+                byte b2 = in.get();
+                byte b3 = in.get();
+                byte b4 = in.get();
+                int code = ((b & 0x07) << 18) | ((b2 & 0x3f) << 12) | ((b3 & 0x3F) << 6) | (b4 & 0x3F);
+                out.put(UTF16Helper.highSurrogate(code));
+                out.put(UTF16Helper.lowSurrogate(code));
+            }
+        }
+    }
+}