specify utf8 encoding

this should fix the following known bugs:
 - putting a U+2019 in the config causes it to become corrupted and
   ~double in size every launch
 - scripts become assembled incorrectly and the nbsp after your name in
   the chatbox becomes incorrect
 - the feed panel doesn't show emoji

cache/src/main/java/net/runelite/cache/fs/flat/FlatStorage.java

@@ -33,6 +33,7 @@ import java.io.InputStream;
 import java.io.InputStreamReader;
 import java.io.OutputStream;
 import java.io.PrintStream;
+import java.nio.charset.StandardCharsets;
 import java.util.ArrayList;
 import java.util.Base64;
 import java.util.Comparator;
@@ -103,7 +104,7 @@ public class FlatStorage implements Storage
 		for (Index idx : store.getIndexes())
 		{
 			String file = idx.getId() + EXTENSION;
-			try (BufferedReader br = new BufferedReader(new InputStreamReader(openReader(file))))
+			try (BufferedReader br = new BufferedReader(new InputStreamReader(openReader(file), StandardCharsets.UTF_8)))
 			{
 				int lineNo = 0;
 				Archive archive = null;
@@ -213,7 +214,7 @@ public class FlatStorage implements Storage
 		for (Index idx : store.getIndexes())
 		{
 			String file = idx.getId() + EXTENSION;
-			try (PrintStream br = new PrintStream(openWriter(file)))
+			try (PrintStream br = new PrintStream(openWriter(file), false, StandardCharsets.UTF_8.name()))
 			{
 				br.printf("protocol=%d\n", idx.getProtocol());
 				br.printf("revision=%d\n", idx.getRevision());

cache/src/main/java/net/runelite/cache/io/OutputStream.java

@@ -26,8 +26,8 @@ package net.runelite.cache.io;
 
 import com.google.common.base.Preconditions;
 import java.io.IOException;
-import java.io.UnsupportedEncodingException;
 import java.nio.ByteBuffer;
+import java.nio.charset.StandardCharsets;
 
 public final class OutputStream extends java.io.OutputStream
 {
@@ -181,16 +181,7 @@ public final class OutputStream extends java.io.OutputStream
 
 	public void writeString(String str)
 	{
-		byte[] b;
-		try
-		{
-			b = str.getBytes("ISO-8859-1");
-		}
-		catch (UnsupportedEncodingException ex)
-		{
-			throw new RuntimeException(ex);
-		}
-		writeBytes(b);
+		writeBytes(str.getBytes(StandardCharsets.ISO_8859_1));
 		writeByte(0);
 	}
 

cache/src/main/java/net/runelite/cache/script/assembler/Assembler.java

@@ -26,6 +26,8 @@ package net.runelite.cache.script.assembler;
 
 import java.io.IOException;
 import java.io.InputStream;
+import java.io.InputStreamReader;
+import java.nio.charset.StandardCharsets;
 import net.runelite.cache.definitions.ScriptDefinition;
 import net.runelite.cache.script.Instructions;
 import net.runelite.cache.script.assembler.rs2asmParser.ProgContext;
@@ -45,7 +47,7 @@ public class Assembler
 	public ScriptDefinition assemble(InputStream in) throws IOException
 	{
 		// Get our lexer
-		rs2asmLexer lexer = new rs2asmLexer(new ANTLRInputStream(in));
+		rs2asmLexer lexer = new rs2asmLexer(new ANTLRInputStream(new InputStreamReader(in, StandardCharsets.UTF_8)));
 
 		LexerErrorListener errorListener = new LexerErrorListener();
 		lexer.addErrorListener(errorListener);

cache/src/test/java/net/runelite/cache/script/assembler/AssemblerTest.java

@@ -25,6 +25,7 @@
 package net.runelite.cache.script.assembler;
 
 import java.io.InputStream;
+import java.nio.charset.StandardCharsets;
 import net.runelite.cache.definitions.ScriptDefinition;
 import net.runelite.cache.script.Instructions;
 import net.runelite.cache.script.disassembler.Disassembler;
@@ -76,7 +77,7 @@ public class AssemblerTest
 		in = AssemblerTest.class.getResourceAsStream(this.script);
 		Assert.assertNotNull(in);
 
-		String original = new String(IOUtils.toByteArray(in)).replaceAll("\r\n", "\n");
+		String original = new String(IOUtils.toByteArray(in), StandardCharsets.UTF_8).replaceAll("\r\n", "\n");
 
 		logger.info(original);
 		logger.info("-----------------------");

cache/src/test/java/net/runelite/cache/script/disassembler/DisassemblerTest.java

@@ -27,6 +27,7 @@ package net.runelite.cache.script.disassembler;
 import com.google.common.io.Files;
 import java.io.File;
 import java.io.IOException;
+import java.nio.charset.StandardCharsets;
 import net.runelite.cache.IndexType;
 import net.runelite.cache.StoreLocation;
 import net.runelite.cache.definitions.ScriptDefinition;
@@ -78,7 +79,7 @@ public class DisassemblerTest
 				Disassembler disassembler = new Disassembler();
 				String out = disassembler.disassemble(script);
 
-				Files.write(out.getBytes(), outFile);
+				Files.write(out.getBytes(StandardCharsets.UTF_8), outFile);
 
 				++count;
 			}

cache/src/test/java/net/runelite/cache/util/XteaTest.java

@@ -24,6 +24,7 @@
  */
 package net.runelite.cache.util;
 
+import java.nio.charset.StandardCharsets;
 import static org.junit.Assert.assertArrayEquals;
 import org.junit.Test;
 
@@ -32,7 +33,7 @@ public class XteaTest
 	@Test
 	public void test()
 	{
-		byte[] data = "testtesttest1".getBytes();
+		byte[] data = "testtesttest1".getBytes(StandardCharsets.UTF_8);
 
 		int[] key = new int[]
 		{

http-api/src/main/java/net/runelite/http/api/account/AccountClient.java

@@ -28,6 +28,7 @@ import com.google.gson.JsonParseException;
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.InputStreamReader;
+import java.nio.charset.StandardCharsets;
 import java.util.UUID;
 import lombok.RequiredArgsConstructor;
 import lombok.extern.slf4j.Slf4j;
@@ -66,7 +67,7 @@ public class AccountClient
 		try (Response response = client.newCall(request).execute())
 		{
 			InputStream in = response.body().byteStream();
-			return RuneLiteAPI.GSON.fromJson(new InputStreamReader(in), OAuthResponse.class);
+			return RuneLiteAPI.GSON.fromJson(new InputStreamReader(in, StandardCharsets.UTF_8), OAuthResponse.class);
 		}
 		catch (JsonParseException ex)
 		{

http-api/src/main/java/net/runelite/http/api/chat/ChatClient.java

@@ -28,6 +28,7 @@ import com.google.gson.JsonParseException;
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.InputStreamReader;
+import java.nio.charset.StandardCharsets;
 import lombok.AllArgsConstructor;
 import net.runelite.http.api.RuneLiteAPI;
 import okhttp3.HttpUrl;
@@ -170,7 +171,7 @@ public class ChatClient
 			}
 
 			InputStream in = response.body().byteStream();
-			return RuneLiteAPI.GSON.fromJson(new InputStreamReader(in), Task.class);
+			return RuneLiteAPI.GSON.fromJson(new InputStreamReader(in, StandardCharsets.UTF_8), Task.class);
 		}
 		catch (JsonParseException ex)
 		{
@@ -307,7 +308,7 @@ public class ChatClient
 			}
 
 			InputStream in = response.body().byteStream();
-			return RuneLiteAPI.GSON.fromJson(new InputStreamReader(in), Duels.class);
+			return RuneLiteAPI.GSON.fromJson(new InputStreamReader(in, StandardCharsets.UTF_8), Duels.class);
 		}
 		catch (JsonParseException ex)
 		{
@@ -354,7 +355,7 @@ public class ChatClient
 			}
 
 			InputStream in = response.body().byteStream();
-			return RuneLiteAPI.GSON.fromJson(new InputStreamReader(in), LayoutRoom[].class);
+			return RuneLiteAPI.GSON.fromJson(new InputStreamReader(in, StandardCharsets.UTF_8), LayoutRoom[].class);
 		}
 		catch (JsonParseException ex)
 		{

http-api/src/main/java/net/runelite/http/api/config/ConfigClient.java

@@ -28,6 +28,7 @@ import com.google.gson.JsonParseException;
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.InputStreamReader;
+import java.nio.charset.StandardCharsets;
 import java.util.UUID;
 import java.util.concurrent.CompletableFuture;
 import lombok.AllArgsConstructor;
@@ -67,7 +68,7 @@ public class ConfigClient
 		try (Response response = client.newCall(request).execute())
 		{
 			InputStream in = response.body().byteStream();
-			return RuneLiteAPI.GSON.fromJson(new InputStreamReader(in), Configuration.class);
+			return RuneLiteAPI.GSON.fromJson(new InputStreamReader(in, StandardCharsets.UTF_8), Configuration.class);
 		}
 		catch (JsonParseException ex)
 		{

http-api/src/main/java/net/runelite/http/api/feed/FeedClient.java

@@ -28,6 +28,7 @@ import com.google.gson.JsonParseException;
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.InputStreamReader;
+import java.nio.charset.StandardCharsets;
 import lombok.RequiredArgsConstructor;
 import lombok.extern.slf4j.Slf4j;
 import net.runelite.http.api.RuneLiteAPI;
@@ -63,7 +64,7 @@ public class FeedClient
 			}
 
 			InputStream in = response.body().byteStream();
-			return RuneLiteAPI.GSON.fromJson(new InputStreamReader(in), FeedResult.class);
+			return RuneLiteAPI.GSON.fromJson(new InputStreamReader(in, StandardCharsets.UTF_8), FeedResult.class);
 		}
 		catch (JsonParseException ex)
 		{

http-api/src/main/java/net/runelite/http/api/item/ItemClient.java

@@ -30,6 +30,7 @@ import java.io.IOException;
 import java.io.InputStream;
 import java.io.InputStreamReader;
 import java.lang.reflect.Type;
+import java.nio.charset.StandardCharsets;
 import java.util.Map;
 import lombok.AllArgsConstructor;
 import lombok.extern.slf4j.Slf4j;
@@ -68,7 +69,7 @@ public class ItemClient
 			}
 
 			InputStream in = response.body().byteStream();
-			return RuneLiteAPI.GSON.fromJson(new InputStreamReader(in), ItemPrice[].class);
+			return RuneLiteAPI.GSON.fromJson(new InputStreamReader(in, StandardCharsets.UTF_8), ItemPrice[].class);
 		}
 		catch (JsonParseException ex)
 		{
@@ -103,7 +104,7 @@ public class ItemClient
 			final Type typeToken = new TypeToken<Map<Integer, ItemStats>>()
 			{
 			}.getType();
-			return RuneLiteAPI.GSON.fromJson(new InputStreamReader(in), typeToken);
+			return RuneLiteAPI.GSON.fromJson(new InputStreamReader(in, StandardCharsets.UTF_8), typeToken);
 		}
 		catch (JsonParseException ex)
 		{

http-api/src/main/java/net/runelite/http/api/loottracker/LootTrackerClient.java

@@ -30,6 +30,7 @@ import com.google.gson.reflect.TypeToken;
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.InputStreamReader;
+import java.nio.charset.StandardCharsets;
 import java.util.Collection;
 import java.util.List;
 import java.util.UUID;
@@ -117,7 +118,7 @@ public class LootTrackerClient
 			}
 
 			InputStream in = response.body().byteStream();
-			return RuneLiteAPI.GSON.fromJson(new InputStreamReader(in), new TypeToken<List<LootAggregate>>()
+			return RuneLiteAPI.GSON.fromJson(new InputStreamReader(in, StandardCharsets.UTF_8), new TypeToken<List<LootAggregate>>()
 			{
 			}.getType());
 		}

http-api/src/main/java/net/runelite/http/api/npc/NpcInfoClient.java

@@ -30,6 +30,7 @@ import java.io.IOException;
 import java.io.InputStream;
 import java.io.InputStreamReader;
 import java.lang.reflect.Type;
+import java.nio.charset.StandardCharsets;
 import java.util.Map;
 import lombok.Value;
 import lombok.extern.slf4j.Slf4j;
@@ -71,7 +72,7 @@ public class NpcInfoClient
 			final Type typeToken = new TypeToken<Map<Integer, NpcInfo>>()
 			{
 			}.getType();
-			return RuneLiteAPI.GSON.fromJson(new InputStreamReader(in), typeToken);
+			return RuneLiteAPI.GSON.fromJson(new InputStreamReader(in, StandardCharsets.UTF_8), typeToken);
 		}
 		catch (JsonParseException ex)
 		{

http-api/src/main/java/net/runelite/http/api/osbuddy/OSBGrandExchangeClient.java

@@ -28,6 +28,7 @@ import com.google.gson.JsonParseException;
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.InputStreamReader;
+import java.nio.charset.StandardCharsets;
 import lombok.AllArgsConstructor;
 import lombok.extern.slf4j.Slf4j;
 import net.runelite.http.api.RuneLiteAPI;
@@ -64,7 +65,7 @@ public class OSBGrandExchangeClient
 			}
 
 			final InputStream in = response.body().byteStream();
-			return RuneLiteAPI.GSON.fromJson(new InputStreamReader(in), OSBGrandExchangeResult.class);
+			return RuneLiteAPI.GSON.fromJson(new InputStreamReader(in, StandardCharsets.UTF_8), OSBGrandExchangeResult.class);
 		}
 		catch (JsonParseException ex)
 		{

http-api/src/main/java/net/runelite/http/api/worlds/WorldClient.java

@@ -29,6 +29,7 @@ import com.google.gson.JsonParseException;
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.InputStreamReader;
+import java.nio.charset.StandardCharsets;
 import lombok.RequiredArgsConstructor;
 import lombok.extern.slf4j.Slf4j;
 import net.runelite.http.api.RuneLiteAPI;
@@ -64,7 +65,7 @@ public class WorldClient
 			}
 
 			InputStream in = response.body().byteStream();
-			return RuneLiteAPI.GSON.fromJson(new InputStreamReader(in), WorldResult.class);
+			return RuneLiteAPI.GSON.fromJson(new InputStreamReader(in, StandardCharsets.UTF_8), WorldResult.class);
 		}
 		catch (JsonParseException ex)
 		{

http-api/src/main/java/net/runelite/http/api/xtea/XteaClient.java

@@ -29,6 +29,7 @@ import com.google.gson.reflect.TypeToken;
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.InputStreamReader;
+import java.nio.charset.StandardCharsets;
 import java.util.List;
 import lombok.AllArgsConstructor;
 import lombok.extern.slf4j.Slf4j;
@@ -103,7 +104,7 @@ public class XteaClient
 		{
 			InputStream in = response.body().byteStream();
 			// CHECKSTYLE:OFF
-			return RuneLiteAPI.GSON.fromJson(new InputStreamReader(in), new TypeToken<List<XteaKey>>() { }.getType());
+			return RuneLiteAPI.GSON.fromJson(new InputStreamReader(in, StandardCharsets.UTF_8), new TypeToken<List<XteaKey>>() { }.getType());
 			// CHECKSTYLE:ON
 		}
 		catch (JsonParseException ex)
@@ -126,7 +127,7 @@ public class XteaClient
 		try (Response response = client.newCall(request).execute())
 		{
 			InputStream in = response.body().byteStream();
-			return RuneLiteAPI.GSON.fromJson(new InputStreamReader(in), XteaKey.class);
+			return RuneLiteAPI.GSON.fromJson(new InputStreamReader(in, StandardCharsets.UTF_8), XteaKey.class);
 		}
 		catch (JsonParseException ex)
 		{

http-service/src/main/java/net/runelite/http/service/feed/FeedController.java

@@ -27,6 +27,7 @@ package net.runelite.http.service.feed;
 import com.google.common.hash.HashCode;
 import com.google.common.hash.Hasher;
 import com.google.common.hash.Hashing;
+import java.nio.charset.StandardCharsets;
 import java.util.ArrayList;
 import java.util.List;
 import java.util.concurrent.TimeUnit;
@@ -66,7 +67,7 @@ public class FeedController
 			Hasher hasher = Hashing.sha256().newHasher();
 			for (FeedItem itemPrice : feedResult.getItems())
 			{
-				hasher.putBytes(itemPrice.getTitle().getBytes()).putBytes(itemPrice.getContent().getBytes());
+				hasher.putBytes(itemPrice.getTitle().getBytes(StandardCharsets.UTF_8)).putBytes(itemPrice.getContent().getBytes(StandardCharsets.UTF_8));
 			}
 			HashCode code = hasher.hash();
 			hash = code.toString();

http-service/src/main/java/net/runelite/http/service/feed/twitter/TwitterService.java

@@ -29,6 +29,7 @@ import java.io.IOException;
 import java.io.InputStream;
 import java.io.InputStreamReader;
 import java.lang.reflect.Type;
+import java.nio.charset.StandardCharsets;
 import java.util.ArrayList;
 import java.util.Base64;
 import java.util.List;
@@ -114,7 +115,7 @@ public class TwitterService
 			{
 			}.getType();
 			List<TwitterStatusesResponseItem> statusesResponse = RuneLiteAPI.GSON
-				.fromJson(new InputStreamReader(in), listType);
+				.fromJson(new InputStreamReader(in, StandardCharsets.UTF_8), listType);
 
 			List<FeedItem> items = new ArrayList<>();
 
@@ -134,7 +135,7 @@ public class TwitterService
 
 	private void updateToken() throws IOException
 	{
-		String encodedCredentials = Base64.getEncoder().encodeToString(credentials.getBytes());
+		String encodedCredentials = Base64.getEncoder().encodeToString(credentials.getBytes(StandardCharsets.UTF_8));
 
 		Request request = new Request.Builder()
 			.url(AUTH_URL)
@@ -151,7 +152,7 @@ public class TwitterService
 
 			InputStream in = response.body().byteStream();
 			TwitterOAuth2TokenResponse tokenResponse = RuneLiteAPI.GSON
-				.fromJson(new InputStreamReader(in), TwitterOAuth2TokenResponse.class);
+				.fromJson(new InputStreamReader(in, StandardCharsets.UTF_8), TwitterOAuth2TokenResponse.class);
 
 			if (!tokenResponse.getTokenType().equals("bearer"))
 			{

http-service/src/main/java/net/runelite/http/service/item/ItemService.java

@@ -28,6 +28,7 @@ import com.google.gson.JsonParseException;
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.InputStreamReader;
+import java.nio.charset.StandardCharsets;
 import java.time.Instant;
 import java.util.ArrayList;
 import java.util.HashSet;
@@ -297,7 +298,7 @@ public class ItemService
 			}
 
 			InputStream in = response.body().byteStream();
-			return RuneLiteAPI.GSON.fromJson(new InputStreamReader(in), clazz);
+			return RuneLiteAPI.GSON.fromJson(new InputStreamReader(in, StandardCharsets.UTF_8), clazz);
 		}
 		catch (JsonParseException ex)
 		{

runelite-client/src/main/java/net/runelite/client/SessionClient.java

@@ -28,6 +28,7 @@ import com.google.gson.JsonParseException;
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.InputStreamReader;
+import java.nio.charset.StandardCharsets;
 import java.util.UUID;
 import lombok.AllArgsConstructor;
 import net.runelite.http.api.RuneLiteAPI;
@@ -58,7 +59,7 @@ class SessionClient
 			ResponseBody body = response.body();
 			
 			InputStream in = body.byteStream();
-			return RuneLiteAPI.GSON.fromJson(new InputStreamReader(in), UUID.class);
+			return RuneLiteAPI.GSON.fromJson(new InputStreamReader(in, StandardCharsets.UTF_8), UUID.class);
 		}
 		catch (JsonParseException | IllegalArgumentException ex) // UUID.fromString can throw IllegalArgumentException
 		{

runelite-client/src/main/java/net/runelite/client/account/SessionManager.java

@@ -27,9 +27,12 @@ package net.runelite.client.account;
 import com.google.gson.Gson;
 import java.io.File;
 import java.io.FileInputStream;
-import java.io.FileWriter;
+import java.io.FileOutputStream;
 import java.io.IOException;
 import java.io.InputStreamReader;
+import java.io.OutputStreamWriter;
+import java.io.Writer;
+import java.nio.charset.StandardCharsets;
 import java.time.Instant;
 import java.util.UUID;
 import javax.inject.Inject;
@@ -91,7 +94,7 @@ public class SessionManager
 
 		try (FileInputStream in = new FileInputStream(sessionFile))
 		{
-			session = new Gson().fromJson(new InputStreamReader(in), AccountSession.class);
+			session = new Gson().fromJson(new InputStreamReader(in, StandardCharsets.UTF_8), AccountSession.class);
 
 			log.debug("Loaded session for {}", session.getUsername());
 		}
@@ -119,7 +122,7 @@ public class SessionManager
 			return;
 		}
 
-		try (FileWriter fw = new FileWriter(sessionFile))
+		try (Writer fw = new OutputStreamWriter(new FileOutputStream(sessionFile), StandardCharsets.UTF_8))
 		{
 			new Gson().toJson(accountSession, fw);
 

runelite-client/src/main/java/net/runelite/client/config/ConfigManager.java

@@ -41,7 +41,6 @@ import java.io.OutputStreamWriter;
 import java.lang.reflect.Method;
 import java.lang.reflect.Modifier;
 import java.lang.reflect.Proxy;
-import java.nio.charset.Charset;
 import java.nio.charset.StandardCharsets;
 import java.nio.file.AtomicMoveNotSupportedException;
 import java.nio.file.Files;
@@ -224,7 +223,7 @@ public class ConfigManager
 		final Properties properties = new Properties();
 		try (FileInputStream in = new FileInputStream(propertiesFile))
 		{
-			properties.load(new InputStreamReader(in, Charset.forName("UTF-8")));
+			properties.load(new InputStreamReader(in, StandardCharsets.UTF_8));
 		}
 		catch (Exception e)
 		{
@@ -295,7 +294,7 @@ public class ConfigManager
 
 		try (FileInputStream in = new FileInputStream(propertiesFile))
 		{
-			properties.load(new InputStreamReader(in, Charset.forName("UTF-8")));
+			properties.load(new InputStreamReader(in, StandardCharsets.UTF_8));
 		}
 		catch (FileNotFoundException ex)
 		{

runelite-client/src/main/java/net/runelite/client/game/ItemVariationMapping.java

@@ -32,6 +32,7 @@ import com.google.gson.Gson;
 import com.google.gson.reflect.TypeToken;
 import java.io.InputStream;
 import java.io.InputStreamReader;
+import java.nio.charset.StandardCharsets;
 import java.util.Collection;
 import java.util.Collections;
 import java.util.Iterator;
@@ -53,7 +54,7 @@ public class ItemVariationMapping
 		};
 
 		final InputStream geLimitData = ItemVariationMapping.class.getResourceAsStream("/item_variations.json");
-		final Map<String, Collection<Integer>> itemVariations = gson.fromJson(new InputStreamReader(geLimitData), typeToken.getType());
+		final Map<String, Collection<Integer>> itemVariations = gson.fromJson(new InputStreamReader(geLimitData, StandardCharsets.UTF_8), typeToken.getType());
 
 		ImmutableMap.Builder<Integer, Integer> builder = new ImmutableMap.Builder<>();
 		ImmutableMultimap.Builder<Integer, Integer> invertedBuilder = new ImmutableMultimap.Builder<>();

runelite-client/src/main/java/net/runelite/client/plugins/gpu/GLUtil.java

@@ -25,6 +25,7 @@
 package net.runelite.client.plugins.gpu;
 
 import com.jogamp.opengl.GL4;
+import java.nio.charset.StandardCharsets;
 
 class GLUtil
 {
@@ -63,14 +64,14 @@ class GLUtil
 	{
 		byte[] err = new byte[ERR_LEN];
 		gl.glGetShaderInfoLog(shader, ERR_LEN, buf, 0, err, 0);
-		return new String(err, 0, buf[0]);
+		return new String(err, 0, buf[0], StandardCharsets.UTF_8);
 	}
 
 	static String glGetProgramInfoLog(GL4 gl, int program)
 	{
 		byte[] err = new byte[ERR_LEN];
 		gl.glGetProgramInfoLog(program, ERR_LEN, buf, 0, err, 0);
-		return new String(err, 0, buf[0]);
+		return new String(err, 0, buf[0], StandardCharsets.UTF_8);
 	}
 
 	static int glGenVertexArrays(GL4 gl)

runelite-client/src/main/java/net/runelite/client/plugins/gpu/template/Template.java

@@ -24,10 +24,13 @@
  */
 package net.runelite.client.plugins.gpu.template;
 
+import com.google.common.io.CharStreams;
+import java.io.IOException;
 import java.io.InputStream;
+import java.io.InputStreamReader;
+import java.nio.charset.StandardCharsets;
 import java.util.ArrayList;
 import java.util.List;
-import java.util.Scanner;
 import java.util.function.Function;
 
 public class Template
@@ -92,7 +95,13 @@ public class Template
 
 	private static String inputStreamToString(InputStream in)
 	{
-		Scanner scanner = new Scanner(in).useDelimiter("\\A");
-		return scanner.next();
+		try
+		{
+			return CharStreams.toString(new InputStreamReader(in, StandardCharsets.UTF_8));
+		}
+		catch (IOException e)
+		{
+			throw new RuntimeException(e);
+		}
 	}
 }

runelite-client/src/main/java/net/runelite/client/plugins/skillcalculator/CacheSkillData.java

@@ -27,6 +27,7 @@ package net.runelite.client.plugins.skillcalculator;
 import com.google.gson.Gson;
 import java.io.InputStream;
 import java.io.InputStreamReader;
+import java.nio.charset.StandardCharsets;
 import java.util.HashMap;
 import java.util.Map;
 import net.runelite.client.plugins.skillcalculator.beans.SkillData;
@@ -43,7 +44,7 @@ class CacheSkillData
 		}
 
 		InputStream skillDataFile = SkillCalculatorPlugin.class.getResourceAsStream(dataFile);
-		SkillData skillData = new Gson().fromJson(new InputStreamReader(skillDataFile), SkillData.class);
+		SkillData skillData = new Gson().fromJson(new InputStreamReader(skillDataFile, StandardCharsets.UTF_8), SkillData.class);
 
 		cache.put(dataFile, skillData);
 		return skillData;

runelite-client/src/main/java/net/runelite/client/plugins/skybox/Skybox.java

@@ -31,6 +31,7 @@ import java.io.IOException;
 import java.io.InputStream;
 import java.io.InputStreamReader;
 import java.io.Reader;
+import java.nio.charset.StandardCharsets;
 import java.util.Arrays;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
@@ -88,7 +89,7 @@ class Skybox
 
 	public Skybox(InputStream is, String filename) throws IOException
 	{
-		this(new InputStreamReader(is), filename);
+		this(new InputStreamReader(is, StandardCharsets.UTF_8), filename);
 	}
 
 	public Skybox(Reader reader, String filename) throws IOException

runelite-client/src/main/java/net/runelite/client/plugins/twitch/TwitchPlugin.java

@@ -26,6 +26,7 @@ package net.runelite.client.plugins.twitch;
 
 import com.google.common.base.Strings;
 import com.google.inject.Provides;
+import java.io.IOException;
 import java.time.temporal.ChronoUnit;
 import java.util.Map;
 import javax.inject.Inject;
@@ -218,8 +219,15 @@ public class TwitchPlugin extends Plugin implements TwitchListener, ChatboxInput
 				return true;
 			}
 
+			try
+			{
 				twitchIRCClient.privmsg(message);
 				addChatMessage(twitchConfig.username(), message);
+			}
+			catch (IOException e)
+			{
+				log.warn("failed to send message", e);
+			}
 
 			return true;
 		}

runelite-client/src/main/java/net/runelite/client/plugins/twitch/irc/TwitchIRCClient.java

@@ -27,8 +27,10 @@ package net.runelite.client.plugins.twitch.irc;
 import java.io.BufferedReader;
 import java.io.IOException;
 import java.io.InputStreamReader;
-import java.io.PrintWriter;
+import java.io.OutputStreamWriter;
+import java.io.Writer;
 import java.net.Socket;
+import java.nio.charset.StandardCharsets;
 import javax.net.SocketFactory;
 import javax.net.ssl.SSLSocketFactory;
 import lombok.extern.slf4j.Slf4j;
@@ -48,7 +50,7 @@ public class TwitchIRCClient extends Thread implements AutoCloseable
 
 	private Socket socket;
 	private BufferedReader in;
-	private PrintWriter out;
+	private Writer out;
 	private long last;
 	private boolean pingSent;
 
@@ -86,8 +88,8 @@ public class TwitchIRCClient extends Thread implements AutoCloseable
 			socket = socketFactory.createSocket(HOST, PORT);
 			socket.setSoTimeout(READ_TIMEOUT);
 
-			in = new BufferedReader(new InputStreamReader(socket.getInputStream()));
-			out = new PrintWriter(socket.getOutputStream());
+			in = new BufferedReader(new InputStreamReader(socket.getInputStream(), StandardCharsets.UTF_8));
+			out = new OutputStreamWriter(socket.getOutputStream(), StandardCharsets.UTF_8);
 		}
 		catch (IOException ex)
 		{
@@ -95,11 +97,11 @@ public class TwitchIRCClient extends Thread implements AutoCloseable
 			return;
 		}
 
+		try
+		{
 			register(username, password);
 			join(channel);
 
-		try
-		{
 			String line;
 
 			while ((line = read()) != null)
@@ -161,10 +163,18 @@ public class TwitchIRCClient extends Thread implements AutoCloseable
 		}
 
 		if (!pingSent && System.currentTimeMillis() - last >= PING_TIMEOUT)
+		{
+			try
 			{
 				ping("twitch");
 				pingSent = true;
 			}
+			catch (IOException e)
+			{
+				log.debug("Ping failure, disconnecting.", e);
+				close();
+			}
+		}
 		else if (pingSent)
 		{
 			log.debug("Ping timeout, disconnecting.");
@@ -172,29 +182,29 @@ public class TwitchIRCClient extends Thread implements AutoCloseable
 		}
 	}
 
-	private void register(String username, String oauth)
+	private void register(String username, String oauth) throws IOException
 	{
 		send("CAP", "REQ", "twitch.tv/commands twitch.tv/tags");
 		send("PASS", oauth);
 		send("NICK", username);
 	}
 
-	private void join(String channel)
+	private void join(String channel) throws IOException
 	{
 		send("JOIN", channel);
 	}
 
-	private void ping(String destination)
+	private void ping(String destination) throws IOException
 	{
 		send("PING", destination);
 	}
 
-	public void privmsg(String message)
+	public void privmsg(String message) throws IOException
 	{
 		send("PRIVMSG", channel, message);
 	}
 
-	private void send(String command, String... args)
+	private void send(String command, String... args) throws IOException
 	{
 		StringBuilder stringBuilder = new StringBuilder();
 		stringBuilder.append(command);

runelite-client/src/main/java/net/runelite/client/rs/ClientConfigLoader.java

@@ -28,6 +28,7 @@ package net.runelite.client.rs;
 import java.io.BufferedReader;
 import java.io.IOException;
 import java.io.InputStreamReader;
+import java.nio.charset.StandardCharsets;
 import lombok.AllArgsConstructor;
 import okhttp3.HttpUrl;
 import okhttp3.OkHttpClient;
@@ -55,7 +56,7 @@ class ClientConfigLoader
 			}
 
 			String str;
-			final BufferedReader in = new BufferedReader(new InputStreamReader(response.body().byteStream()));
+			final BufferedReader in = new BufferedReader(new InputStreamReader(response.body().byteStream(), StandardCharsets.UTF_8));
 			while ((str = in.readLine()) != null)
 			{
 				int idx = str.indexOf('=');

runelite-client/src/main/java/net/runelite/client/util/ImageCapture.java

@@ -35,6 +35,7 @@ import java.io.File;
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.InputStreamReader;
+import java.nio.charset.StandardCharsets;
 import java.nio.file.Files;
 import java.text.DateFormat;
 import java.text.SimpleDateFormat;
@@ -215,7 +216,7 @@ public class ImageCapture
 				try (InputStream in = response.body().byteStream())
 				{
 					ImageUploadResponse imageUploadResponse = RuneLiteAPI.GSON
-						.fromJson(new InputStreamReader(in), ImageUploadResponse.class);
+						.fromJson(new InputStreamReader(in, StandardCharsets.UTF_8), ImageUploadResponse.class);
 
 					if (imageUploadResponse.isSuccess())
 					{

runelite-client/src/test/java/net/runelite/client/plugins/discord/DiscordStateTest.java

@@ -27,6 +27,7 @@ package net.runelite.client.plugins.discord;
 import com.google.inject.Guice;
 import com.google.inject.testing.fieldbinder.Bind;
 import com.google.inject.testing.fieldbinder.BoundFieldModule;
+import java.nio.charset.StandardCharsets;
 import java.util.List;
 import java.util.UUID;
 import javax.inject.Inject;
@@ -72,7 +73,7 @@ public class DiscordStateTest
 	public void before()
 	{
 		Guice.createInjector(BoundFieldModule.of(this)).injectMembers(this);
-		when(partyService.getLocalPartyId()).thenReturn(UUID.nameUUIDFromBytes("test".getBytes()));
+		when(partyService.getLocalPartyId()).thenReturn(UUID.nameUUIDFromBytes("test".getBytes(StandardCharsets.UTF_8)));
 	}
 
 	@Test