Fix some code syle issues.

Author: ikarus23

Mifare Classic Tool/app/src/main/java/de/syss/MifareClassicTool/Activities/DumpEditor.java

@@ -739,7 +739,7 @@ private void decodeValueBlocks() {
             }
         }
 
-        if (tmpVBs.size() > 0) {
+        if (!tmpVBs.isEmpty()) {
             String[] vb = tmpVBs.toArray(new String[0]);
             Intent intent = new Intent(this, ValueBlocksToInt.class);
             intent.putExtra(ValueBlocksToInt.EXTRA_VB, vb);

Mifare Classic Tool/app/src/main/java/de/syss/MifareClassicTool/Activities/KeyMapCreator.java

@@ -366,7 +366,7 @@ public void onCreateKeyMap(View view) {
                 fileNames.add(c.getText().toString());
             }
         }
-        if (fileNames.size() > 0) {
+        if (!fileNames.isEmpty()) {
             // Check if key files still exists.
             ArrayList<File> keyFiles = new ArrayList<>();
             for (String fileName : fileNames) {
@@ -384,7 +384,7 @@ public void onCreateKeyMap(View view) {
                             + "doesn't exists anymore.");
                 }
             }
-            if (keyFiles.size() > 0) {
+            if (!keyFiles.isEmpty()) {
                 // Save last selected key files as "/"-separated string
                 // (if corresponding setting is active).
                 if (saveLastUsedKeyFiles) {

Mifare Classic Tool/app/src/main/java/de/syss/MifareClassicTool/Activities/WriteTag.java

@@ -799,7 +799,7 @@ private void checkDumpAndShowSectorChooserDialog(final String[] dump) {
                             mDumpWithPos.remove(sector);
                         }
                     }
-                    if (mDumpWithPos.size() == 0) {
+                    if (mDumpWithPos.isEmpty()) {
                         // Error. There is nothing to write.
                         Toast.makeText(context, R.string.info_nothing_to_write,
                                 Toast.LENGTH_LONG).show();
@@ -1147,7 +1147,7 @@ private void checkDumpAgainstTag() {
         }
 
         // Show skip/cancel dialog (if needed).
-        if (list.size() != 0) {
+        if (!list.isEmpty()) {
             // If the user skips all sectors/blocks that are not writable,
             // the writeTag() method will be called.
             LinearLayout ll = new LinearLayout(this);
@@ -1222,7 +1222,7 @@ private void writeDump(
             final HashMap<Integer, HashMap<Integer, Integer>> writeOnPos,
             final SparseArray<byte[][]> keyMap) {
         // Check for write data.
-        if (writeOnPos.size() == 0) {
+        if (writeOnPos.isEmpty()) {
             // Nothing to write. Exit.
             Toast.makeText(this, R.string.info_nothing_to_write,
                     Toast.LENGTH_LONG).show();

Mifare Classic Tool/app/src/main/java/de/syss/MifareClassicTool/Common.java

@@ -425,7 +425,7 @@ private static String[] readLineByLine(BufferedReader reader,
             Log.e(LOG_TAG, "Error while reading from file.", ex);
             ret = null;
         }
-        if (linesArray.size() > 0) {
+        if (!linesArray.isEmpty()) {
             ret = linesArray.toArray(new String[0]);
         } else {
             ret = new String[]{""};

Mifare Classic Tool/app/src/main/java/de/syss/MifareClassicTool/MCDiffUtils.java

@@ -70,7 +70,7 @@ public static SparseArray<Integer[][]> diffIndices(
                         diffIndices.add(k);
                     }
                 }
-                if (diffIndices.size() == 0) {
+                if (diffIndices.isEmpty()) {
                     // Block was identical.
                     diffSector[j] = new Integer[0];
                 } else {

Mifare Classic Tool/app/src/main/java/de/syss/MifareClassicTool/MCReader.java

@@ -803,7 +803,7 @@ public HashMap<Integer, HashMap<Integer, Integer>> isWritableOnPositions(
                     }
 
                 }
-                if (blockWithWriteInfo.size() > 0) {
+                if (!blockWithWriteInfo.isEmpty()) {
                     ret.put(sector, blockWithWriteInfo);
                 }
             }
@@ -845,7 +845,7 @@ public int setKeyFile(File[] keyFiles, Context context) {
                 }
             }
         }
-        if (keys.size() > 0) {
+        if (!keys.isEmpty()) {
             mHasAllZeroKey = keys.contains("000000000000");
             mKeysWithOrder = new ArrayList<>(keys);
             if (mHasAllZeroKey) {