Guava中的Joiner使用

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Joiner拼接List中的字符串

List<String> strList = Arrays.asList("java", "go", "c++", "c#");
String str = Joiner.on("$").join(strList);

拼接字符串过滤null值

List<String> strListContainNull = Arrays.asList("java", "go", "c++", null, "c#");
String strContainNull = Joiner.on("$").skipNulls().join(strListContainNull);

拼接的时候替换null值

List<String> strListReplaceNull = Arrays.asList("java", "go", "c++", null, "c#");
String strReplaceNull = Joiner.on("$").useForNull("default_null").join(strListReplaceNull);

直接拼接到StringBuilder或者StringBuild中

StringBuilder sb = new StringBuilder("hello,hello,hello");
StringBuilder newSb = Joiner.on("$").appendTo(sb, strList);
System.out.println(sb.toString());
System.out.println(newSb);
System.out.println(sb == newSb);

直接写入文件中

try (FileWriter writer = new FileWriter(new File("D:\test.txt"))) {
    Joiner.on("$").appendTo(writer, strList);
} catch (IOException e) {
    e.printStackTrace();
}

Joiner拼接map

Map<String,String> map = new HashMap<>();
map.put("hello","java");
map.put("hi","c++");
String strMap = Joiner.on("#").withKeyValueSeparator("-").join(map);