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Commit43128ab

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Code samples
1 parent70a38ae commit43128ab

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3 files changed

+53
-34
lines changed

3 files changed

+53
-34
lines changed

‎src/com/winterbe/java8/samples/misc/Files1.java

Lines changed: 29 additions & 16 deletions
Original file line numberDiff line numberDiff line change
@@ -7,6 +7,7 @@
77
importjava.nio.file.Path;
88
importjava.nio.file.Paths;
99
importjava.util.List;
10+
importjava.util.stream.Collectors;
1011
importjava.util.stream.Stream;
1112

1213
/**
@@ -26,25 +27,26 @@ public static void main(String[] args) throws IOException {
2627
}
2728

2829
privatestaticvoidtestReaderLines()throwsIOException {
29-
try (BufferedReaderreader =
30-
Files.newBufferedReader(Paths.get("res","nashorn1.js"))) {
31-
longcountPrints =reader.lines()
30+
Pathpath =Paths.get("res/nashorn1.js");
31+
try (BufferedReaderreader =Files.newBufferedReader(path)) {
32+
longcountPrints =reader
33+
.lines()
3234
.filter(line ->line.contains("print"))
3335
.count();
3436
System.out.println(countPrints);
3537
}
3638
}
3739

3840
privatestaticvoidtestWriter()throwsIOException {
39-
try (BufferedWriterwriter =
40-
Files.newBufferedWriter(Paths.get("res","output.js"))) {
41+
Pathpath =Paths.get("res/output.js");
42+
try (BufferedWriterwriter =Files.newBufferedWriter(path)) {
4143
writer.write("print('Hello World');");
4244
}
4345
}
4446

4547
privatestaticvoidtestReader()throwsIOException {
46-
try (BufferedReaderreader =
47-
Files.newBufferedReader(Paths.get("res","nashorn1.js"))) {
48+
Pathpath =Paths.get("res/nashorn1.js");
49+
try (BufferedReaderreader =Files.newBufferedReader(path)) {
4850
System.out.println(reader.readLine());
4951
}
5052
}
@@ -53,10 +55,11 @@ private static void testWalk() throws IOException {
5355
Pathstart =Paths.get("");
5456
intmaxDepth =5;
5557
try (Stream<Path>stream =Files.walk(start,maxDepth)) {
56-
longfileCount =stream
57-
.filter(path ->String.valueOf(path).endsWith(".js"))
58-
.count();
59-
System.out.format("JS files found: %s",fileCount);
58+
Stringjoined =stream
59+
.map(String::valueOf)
60+
.filter(path ->path.endsWith(".js"))
61+
.collect(Collectors.joining("; "));
62+
System.out.println("walk(): " +joined);
6063
}
6164
}
6265

@@ -65,26 +68,36 @@ private static void testFind() throws IOException {
6568
intmaxDepth =5;
6669
try (Stream<Path>stream =Files.find(start,maxDepth, (path,attr) ->
6770
String.valueOf(path).endsWith(".js"))) {
68-
stream.sorted().forEach(System.out::println);
71+
Stringjoined =stream
72+
.sorted()
73+
.map(String::valueOf)
74+
.collect(Collectors.joining("; "));
75+
System.out.println("find(): " +joined);
6976
}
7077
}
7178

7279
privatestaticvoidtestList()throwsIOException {
73-
try (Stream<Path>stream =Files.list(Paths.get("/usr"))) {
74-
stream.sorted().forEach(System.out::println);
80+
try (Stream<Path>stream =Files.list(Paths.get(""))) {
81+
Stringjoined =stream
82+
.map(String::valueOf)
83+
.filter(path -> !path.startsWith("."))
84+
.sorted()
85+
.collect(Collectors.joining("; "));
86+
System.out.println("list(): " +joined);
7587
}
7688
}
7789

7890
privatestaticvoidtestLines()throwsIOException {
79-
try (Stream<String>stream =Files.lines(Paths.get("res","nashorn1.js"))) {
91+
try (Stream<String>stream =Files.lines(Paths.get("res/nashorn1.js"))) {
8092
stream
8193
.filter(line ->line.contains("print"))
94+
.map(String::trim)
8295
.forEach(System.out::println);
8396
}
8497
}
8598

8699
privatestaticvoidtestReadWriteLines()throwsIOException {
87-
List<String>lines =Files.readAllLines(Paths.get("res","nashorn1.js"));
100+
List<String>lines =Files.readAllLines(Paths.get("res/nashorn1.js"));
88101
lines.add("print('foobar');");
89102
Files.write(Paths.get("res","nashorn1-modified.js"),lines);
90103
}

‎src/com/winterbe/java8/samples/misc/Math1.java

Lines changed: 6 additions & 5 deletions
Original file line numberDiff line numberDiff line change
@@ -30,28 +30,29 @@ private static void testUnsignedInt() {
3030
System.out.println(string2);
3131

3232
try {
33-
System.out.println(Integer.parseInt(string,10));
33+
Integer.parseInt(string,10);
3434
}
3535
catch (NumberFormatExceptione) {
36-
System.out.println("could not parse signed int of " +maxUnsignedInt);
36+
System.err.println("could not parse signed int of " +maxUnsignedInt);
3737
}
3838
}
3939

4040
privatestaticvoidtestMathExact() {
41+
System.out.println(Integer.MAX_VALUE);
4142
System.out.println(Integer.MAX_VALUE +1);
4243

4344
try {
4445
Math.addExact(Integer.MAX_VALUE,1);
4546
}
4647
catch (ArithmeticExceptione) {
47-
System.out.println(e.getMessage());
48+
System.err.println(e.getMessage());
4849
}
4950

5051
try {
5152
Math.toIntExact(Long.MAX_VALUE);
5253
}
53-
catch (Exceptione) {
54-
System.out.println(e.getMessage());
54+
catch (ArithmeticExceptione) {
55+
System.err.println(e.getMessage());
5556
}
5657
}
5758
}
Lines changed: 18 additions & 13 deletions
Original file line numberDiff line numberDiff line change
@@ -1,7 +1,8 @@
11
packagecom.winterbe.java8.samples.misc;
22

3-
importjava.util.function.Predicate;
43
importjava.util.regex.Pattern;
4+
importjava.util.stream.Collectors;
5+
importjava.util.stream.Stream;
56

67
/**
78
* @author Benjamin Winterberg
@@ -16,29 +17,33 @@ public static void main(String[] args) {
1617
}
1718

1819
privatestaticvoidtestChars() {
19-
Stringstring ="foobar";
20-
string.chars()
21-
.filter(c ->c >100)
22-
.mapToObj(c -> (char)c)
23-
.forEach(System.out::println);
20+
Stringstring ="foobar:foo:bar"
21+
.chars()
22+
.distinct()
23+
.mapToObj(c ->String.valueOf((char)c))
24+
.sorted()
25+
.collect(Collectors.joining());
26+
System.out.println(string);
2427
}
2528

2629
privatestaticvoidtestPatternSplit() {
27-
Pattern.compile(":")
30+
Stringstring =Pattern.compile(":")
2831
.splitAsStream("foobar:foo:bar")
32+
.filter(s ->s.contains("bar"))
2933
.sorted()
30-
.forEach(System.out::println);
34+
.collect(Collectors.joining(":"));
35+
System.out.println(string);
3136
}
3237

3338
privatestaticvoidtestPatternPredicate() {
34-
Patternpattern =Pattern.compile(".*123.*");
35-
Predicate<String>predicate =pattern.asPredicate();
36-
System.out.println(predicate.test("a123b"));
37-
System.out.println(predicate.test("boom"));
39+
longcount =Stream.of("bob@gmail.com","alice@hotmail.com")
40+
.filter(Pattern.compile(".*@gmail\\.com").asPredicate())
41+
.count();
42+
System.out.println(count);
3843
}
3944

4045
privatestaticvoidtestJoin() {
41-
Stringstring =String.join(";","a","b","c","d");
46+
Stringstring =String.join(":","foobar","foo","bar");
4247
System.out.println(string);
4348
}
4449
}

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