make use of autoclosable for stream writers/readers to simplify code

.gitignore

@@ -45,6 +45,8 @@ src/main/resources/META-INF/
 /.project
 /.classpath
 /.settings/
+/.apt_generated/
 
 # output directory
 /output-directory/
+

src/main/java/org/tron/common/utils/FileUtil.java

@@ -83,27 +83,23 @@ public static boolean recursiveDelete(String fileName) {
   }
 
   public static void saveData(String filePath, String data, boolean append) {
+    File priFile = new File(filePath);
     try {
-      File priFile = new File(filePath);
       priFile.createNewFile();
-      FileWriter fw = new FileWriter(priFile, append);
-      BufferedWriter bw = new BufferedWriter(fw);
-      bw.write(data);
-      bw.flush();
-      bw.close();
+      try (BufferedWriter bw = new BufferedWriter(new FileWriter(priFile, append))) {
+        bw.write(data);
+        bw.flush();
+      }
     } catch (IOException e) {
       e.printStackTrace();
     }
   }
 
   public static int readData(String filePath, char[] buf) {
     int len;
-    try {
-      File file = new File(filePath);
-      FileReader fileReader = new FileReader(file);
-      BufferedReader bufRead = new BufferedReader(fileReader);
+    File file = new File(filePath);
+    try (BufferedReader bufRead = new BufferedReader(new FileReader(file))) {
       len = bufRead.read(buf, 0, buf.length);
-      bufRead.close();
     } catch (FileNotFoundException ex) {
       ex.printStackTrace();
       return 0;

src/main/java/org/tron/core/Sha256Hash.java

@@ -18,10 +18,6 @@
  */
 
 import static com.google.common.base.Preconditions.checkArgument;
-
-import com.google.common.io.ByteStreams;
-import com.google.common.primitives.Ints;
-import com.google.protobuf.ByteString;
 import java.io.File;
 import java.io.FileInputStream;
 import java.io.IOException;
@@ -30,6 +26,9 @@
 import java.security.MessageDigest;
 import java.security.NoSuchAlgorithmException;
 import java.util.Arrays;
+import com.google.common.io.ByteStreams;
+import com.google.common.primitives.Ints;
+import com.google.protobuf.ByteString;
 
 /**
  * A Sha256Hash just wraps a byte[] so that equals and hashcode work correctly, allowing it to be
@@ -96,11 +95,9 @@ public static Sha256Hash of(byte[] contents) {
    * @throws IOException if an error occurs while reading the file
    */
   public static Sha256Hash of(File file) throws IOException {
-    FileInputStream in = new FileInputStream(file);
-    try {
+
+    try (FileInputStream in = new FileInputStream(file)) {
       return of(ByteStreams.toByteArray(in));
-    } finally {
-      in.close();
     }
   }
 

src/main/java/org/tron/core/TronBlockChainImpl.java

@@ -20,8 +20,6 @@
 
 
 import static org.tron.core.Constant.LAST_HASH;
-
-import com.google.protobuf.InvalidProtocolBufferException;
 import java.io.BufferedWriter;
 import java.io.File;
 import java.io.FileWriter;
@@ -36,6 +34,7 @@
 import org.tron.core.config.SystemProperties;
 import org.tron.core.db.BlockStoreInput;
 import org.tron.protos.Protocal.Block;
+import com.google.protobuf.InvalidProtocolBufferException;
 
 @Component
 public class TronBlockChainImpl implements TronBlockChain, org.tron.core.facade.TronBlockChain {
@@ -111,8 +110,6 @@ private void recordBlock(Block block) {
     String dumpDir = config.databaseDir() + "/" + config.dumpDir();
 
     File dumpFile = new File(dumpDir + "/blocks-rec.dmp");
-    FileWriter fw = null;
-    BufferedWriter bw = null;
 
     try {
 
@@ -121,24 +118,13 @@ private void recordBlock(Block block) {
         dumpFile.createNewFile();
       }
 
-      fw = new FileWriter(dumpFile.getAbsoluteFile(), true);
-      bw = new BufferedWriter(fw);
+      try (BufferedWriter bw =
+          new BufferedWriter(new FileWriter(dumpFile.getAbsoluteFile(), true))) {
       bw.write(Hex.toHexString(block.toByteArray()));
       bw.write("\n");
-
+      }
     } catch (IOException e) {
       logger.error(e.getMessage(), e);
-    } finally {
-      try {
-        if (bw != null) {
-          bw.close();
-        }
-        if (fw != null) {
-          fw.close();
-        }
-      } catch (IOException e) {
-        e.printStackTrace();
-      }
     }
   }
 }

src/test/java/org/tron/core/consensus/client/ReadIp.java

@@ -26,27 +26,15 @@ public class ReadIp {
    * readFile from path.
    */
   public String readFile(String path) {
-    BufferedReader reader = null;
     String laststr = "";
-    try {
-      FileInputStream fileInputStream = new FileInputStream(path);
-      InputStreamReader inputStreamReader = new InputStreamReader(fileInputStream, "UTF-8");
-      reader = new BufferedReader(inputStreamReader);
+    try (BufferedReader reader =
+        new BufferedReader(new InputStreamReader(new FileInputStream(path), "UTF-8"))) {
       String tempString = null;
       while ((tempString = reader.readLine()) != null) {
         laststr += tempString;
       }
-      reader.close();
     } catch (IOException e) {
       e.printStackTrace();
-    } finally {
-      if (reader != null) {
-        try {
-          reader.close();
-        } catch (IOException e) {
-          e.printStackTrace();
-        }
-      }
     }
     return laststr;
   }