[hotfix][test] Move some auto-closable variables into try-block to manage the closing of objects for MassiveStringSorting.java and MassiveStringValueSorting.java

Co-authored-by: spuru9 <sinhapurushottam911@gmail.com>

Author: RocMarshal

flink-tests/src/test/java/org/apache/flink/test/manual/MassiveStringSorting.java

@@ -363,9 +363,7 @@ private File generateFileWithStrings(int numStrings, String prefix) throws IOExc
         bld.append(prefix);
 
         File f = File.createTempFile("strings", "txt");
-        BufferedWriter wrt = null;
-        try {
-            wrt = new BufferedWriter(new FileWriter(f));
+        try (BufferedWriter wrt = new BufferedWriter(new FileWriter(f))) {
 
             for (int i = 0; i < numStrings; i++) {
                 bld.setLength(resetValue);
@@ -380,8 +378,6 @@ private File generateFileWithStrings(int numStrings, String prefix) throws IOExc
                 wrt.write(str);
                 wrt.newLine();
             }
-        } finally {
-            wrt.close();
         }
 
         return f;
@@ -393,9 +389,7 @@ private File generateFileWithStringTuples(int numStrings, String prefix) throws
         final StringBuilder bld = new StringBuilder();
 
         File f = File.createTempFile("strings", "txt");
-        BufferedWriter wrt = null;
-        try {
-            wrt = new BufferedWriter(new FileWriter(f));
+        try (BufferedWriter wrt = new BufferedWriter(new FileWriter(f))) {
 
             for (int i = 0; i < numStrings; i++) {
                 bld.setLength(0);
@@ -420,8 +414,6 @@ private File generateFileWithStringTuples(int numStrings, String prefix) throws
                 wrt.write(str);
                 wrt.newLine();
             }
-        } finally {
-            wrt.close();
         }
 
         return f;

flink-tests/src/test/java/org/apache/flink/test/manual/MassiveStringValueSorting.java

@@ -389,9 +389,7 @@ private File generateFileWithStrings(int numStrings, String prefix) throws IOExc
         bld.append(prefix);
 
         File f = File.createTempFile("strings", "txt");
-        BufferedWriter wrt = null;
-        try {
-            wrt = new BufferedWriter(new FileWriter(f));
+        try (BufferedWriter wrt = new BufferedWriter(new FileWriter(f))) {
 
             for (int i = 0; i < numStrings; i++) {
                 bld.setLength(resetValue);
@@ -406,10 +404,6 @@ private File generateFileWithStrings(int numStrings, String prefix) throws IOExc
                 wrt.write(str);
                 wrt.newLine();
             }
-        } finally {
-            if (wrt != null) {
-                wrt.close();
-            }
         }
 
         return f;
@@ -421,9 +415,7 @@ private File generateFileWithStringTuples(int numStrings, String prefix) throws
         final StringBuilder bld = new StringBuilder();
 
         File f = File.createTempFile("strings", "txt");
-        BufferedWriter wrt = null;
-        try {
-            wrt = new BufferedWriter(new FileWriter(f));
+        try (BufferedWriter wrt = new BufferedWriter(new FileWriter(f))) {
 
             for (int i = 0; i < numStrings; i++) {
                 bld.setLength(0);
@@ -448,10 +440,6 @@ private File generateFileWithStringTuples(int numStrings, String prefix) throws
                 wrt.write(str);
                 wrt.newLine();
             }
-        } finally {
-            if (wrt != null) {
-                wrt.close();
-            }
         }
 
         return f;