diff --git a/build.xml b/build.xml
index 9f4c208..33000ff 100644
--- a/build.xml
+++ b/build.xml
@@ -26,7 +26,7 @@
 
   <target name="compile" depends="init,clean">
     <mkdir dir="${out}"/>
-    <javac srcdir="${src}" destdir="${out}" source="1.6" target="1.6" encoding="UTF-8" debug="true" includeantruntime="false"/>
+    <javac srcdir="${src}" destdir="${out}" source="1.7" target="1.7" encoding="UTF-8" debug="true" includeantruntime="false"/>
   </target>
 
   <target name="dist" depends="init,compile">
@@ -39,7 +39,7 @@
 
   <target name="test-compile" depends="init,compile">
     <mkdir dir="${test-out}"/>
-    <javac srcdir="${test-src}" destdir="${test-out}" source="1.6" target="1.6" encoding="UTF-8" debug="true" includeantruntime="false">
+    <javac srcdir="${test-src}" destdir="${test-out}" source="1.7" target="1.7" encoding="UTF-8" debug="true" includeantruntime="false">
       <classpath path="${out}"/>
       <classpath refid="junit"/>
     </javac>
diff --git a/src/org/jetbrains/java/decompiler/modules/decompiler/exps/ConstExprent.java b/src/org/jetbrains/java/decompiler/modules/decompiler/exps/ConstExprent.java
index 179b2ba..2a91a65 100644
--- a/src/org/jetbrains/java/decompiler/modules/decompiler/exps/ConstExprent.java
+++ b/src/org/jetbrains/java/decompiler/modules/decompiler/exps/ConstExprent.java
@@ -28,12 +28,13 @@ import org.jetbrains.java.decompiler.struct.match.MatchNode;
 import org.jetbrains.java.decompiler.struct.match.IMatchable.MatchProperties;
 import org.jetbrains.java.decompiler.struct.match.MatchNode.RuleValue;
 import org.jetbrains.java.decompiler.util.InterpreterUtil;
+import org.jetbrains.java.decompiler.util.TextUtil;
 
 import java.util.*;
 import java.util.Map.Entry;
 
 public class ConstExprent extends Exprent {
-  private static final Map<Integer, String> ESCAPES = new HashMap<Integer, String>() {{
+  private static final Map<Integer, String> CHAR_ESCAPES = new HashMap<Integer, String>() {{
     put(new Integer(0x8), "\\b");   /* \u0008: backspace BS */
     put(new Integer(0x9), "\\t");   /* \u0009: horizontal tab HT */
     put(new Integer(0xA), "\\n");   /* \u000a: linefeed LF */
@@ -127,17 +128,17 @@ public class ConstExprent extends Exprent {
           return new TextBuffer(Boolean.toString(((Integer)value).intValue() != 0));
         case CodeConstants.TYPE_CHAR:
           Integer val = (Integer)value;
-          String ret = ESCAPES.get(val);
+          String ret = CHAR_ESCAPES.get(val);
           if (ret == null) {
             char c = (char)val.intValue();
-            if (c >= 32 && c < 127 || !ascii && InterpreterUtil.isPrintableUnicode(c)) {
+            if (isPrintableAscii(c) || !ascii && TextUtil.isPrintableUnicode(c)) {
               ret = String.valueOf(c);
             }
             else {
-              ret = InterpreterUtil.charToUnicodeLiteral(c);
+              ret = TextUtil.charToUnicodeLiteral(c);
             }
           }
-          return new TextBuffer(ret).enclose("\'", "\'");
+          return new TextBuffer(ret).enclose("'", "'");
         case CodeConstants.TYPE_BYTE:
         case CodeConstants.TYPE_BYTECHAR:
         case CodeConstants.TYPE_SHORT:
@@ -306,7 +307,7 @@ public class ConstExprent extends Exprent {
           buffer.append("\\\'");
           break;
         default:
-          if (c >= 32 && c < 127 || !ascii && InterpreterUtil.isPrintableUnicode(c)) {
+          if (c >= 32 && c < 127 || !ascii && TextUtil.isPrintableUnicode(c)) {
             buffer.append(c);
           }
           else {
@@ -393,7 +394,7 @@ public class ConstExprent extends Exprent {
     // BYTECHAR and SHORTCHAR => CHAR in the CHAR context
     if (expectedType.equals(VarType.VARTYPE_CHAR) &&
             (constType.equals(VarType.VARTYPE_BYTECHAR) || constType.equals(VarType.VARTYPE_SHORTCHAR))) {
-      if (getIntValue() != 0) {
+      if (isPrintableAscii(getIntValue())) {
         setConstType(VarType.VARTYPE_CHAR);
       }
     }
@@ -404,6 +405,11 @@ public class ConstExprent extends Exprent {
     }
   }
 
+  private static boolean isPrintableAscii(int c) {
+    return c >= 32 && c < 127;
+  }
+
+
   public Object getValue() {
     return value;
   }
diff --git a/src/org/jetbrains/java/decompiler/util/TextUtil.java b/src/org/jetbrains/java/decompiler/util/TextUtil.java
index 14e24f9..21f10e4 100644
--- a/src/org/jetbrains/java/decompiler/util/TextUtil.java
+++ b/src/org/jetbrains/java/decompiler/util/TextUtil.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2000-2014 JetBrains s.r.o.
+ * Copyright 2000-2016 JetBrains s.r.o.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -15,12 +15,23 @@
  */
 package org.jetbrains.java.decompiler.util;
 
+import org.jetbrains.java.decompiler.code.CodeConstants;
 import org.jetbrains.java.decompiler.main.ClassesProcessor;
 import org.jetbrains.java.decompiler.main.DecompilerContext;
 import org.jetbrains.java.decompiler.main.TextBuffer;
+import org.jetbrains.java.decompiler.main.extern.IFernflowerPreferences;
 import org.jetbrains.java.decompiler.modules.decompiler.ExprProcessor;
 
+import java.util.Arrays;
+import java.util.HashSet;
+
 public class TextUtil {
+  private static final HashSet<String> KEYWORDS = new HashSet<>(Arrays.asList(
+    "abstract", "default", "if", "private", "this", "boolean", "do", "implements", "protected", "throw", "break", "double", "import",
+    "public", "throws", "byte", "else", "instanceof", "return", "transient", "case", "extends", "int", "short", "try", "catch", "final",
+    "interface", "static", "void", "char", "finally", "long", "strictfp", "volatile", "class", "float", "native", "super", "while",
+    "const", "for", "new", "switch", "continue", "goto", "package", "synchronized", "true", "false", "null", "assert"));
+
   public static void writeQualifiedSuper(TextBuffer buf, String qualifier) {
     ClassesProcessor.ClassNode classNode = (ClassesProcessor.ClassNode)DecompilerContext.getProperty(DecompilerContext.CURRENT_CLASS_NODE);
     if (!qualifier.equals(classNode.classStruct.qualifiedName)) {
@@ -28,4 +39,48 @@ public class TextUtil {
     }
     buf.append("super");
   }
-}
+
+  public static String getIndentString(int length) {
+    if (length == 0) return "";
+    StringBuilder buf = new StringBuilder();
+    String indent = (String)DecompilerContext.getProperty(IFernflowerPreferences.INDENT_STRING);
+    while (length-- > 0) {
+      buf.append(indent);
+    }
+    return buf.toString();
+  }
+
+  public static boolean isPrintableUnicode(char c) {
+    int t = Character.getType(c);
+    return t != Character.UNASSIGNED && t != Character.LINE_SEPARATOR && t != Character.PARAGRAPH_SEPARATOR &&
+           t != Character.CONTROL && t != Character.FORMAT && t != Character.PRIVATE_USE && t != Character.SURROGATE;
+  }
+
+  public static String charToUnicodeLiteral(int value) {
+    String sTemp = Integer.toHexString(value);
+    sTemp = ("0000" + sTemp).substring(sTemp.length());
+    return "\\u" + sTemp;
+  }
+
+  public static boolean isValidIdentifier(String id, int version) {
+    return isJavaIdentifier(id) && !isKeyword(id, version);
+  }
+
+  private static boolean isJavaIdentifier(String id) {
+    if (id.isEmpty() || !Character.isJavaIdentifierStart(id.charAt(0))) {
+      return false;
+    }
+
+    for (int i = 1; i < id.length(); i++) {
+      if (!Character.isJavaIdentifierPart(id.charAt(i))) {
+        return false;
+      }
+    }
+
+    return true;
+  }
+
+  private static boolean isKeyword(String id, int version) {
+    return KEYWORDS.contains(id) || version > CodeConstants.BYTECODE_JAVA_5 && "enum".equals(id);
+  }
+}
\ No newline at end of file