GuavaJoiner、Splitter使用

Z时代
2024-01-10
分类：综合

1、List转String


public static List<String> strings = Arrays.asList("test1","test2","test3");
@Test
public void test3(){
    String str = Joiner.on(",").join(strings);
System.out.println(str);
}

结果：

test1,test2,test3

2、String转List


public static String str = "test1,test2,test3";
@Test
public void test4(){
    List<String> platforms = Splitter.on(",").trimResults().splitToList(str);
System.out.println(platforms);
}

结果：


[test1, test2, test3]

3、useForNull替换null值


public static List<String> stringList = Arrays.asList("test1",null,"test3");
@Test
public void test5(){
    String result = Joiner.on(",").useForNull("null").join(stringList);
System.out.println(result);
}

结果：

test1,null,test3

4、skipNulls跳过null值


public static List<String> stringList = Arrays.asList("test1",null,"test3");
@Test
public void test5(){
    String result = Joiner.on(",").skipNulls().join(stringList);
System.out.println(result);
}

结果：

test1,test3

5、appendTo

它的功能是可以把集合转成StringBuilder或者StringBuffer


public static List<String> stringList = Arrays.asList("test1","test2","test3");
@Test
public void test5(){
    StringBuilder result = Joiner.on(",").appendTo(new StringBuilder(), stringList);
System.out.println(result);
}

6、Splitter用途


@Test
public void test4(){
    String str = "test1,test2,, test4,";
// 只切割转换List
Splitter.on(",").split(str).forEach(System.out::println);
System.out.println("----");
// 切割字符串转List，去掉空值
Splitter.on(",").omitEmptyStrings().split(str).forEach(System.out::println);
System.out.println("----");
// 切割字符串转List，去掉空值，去掉空格
Splitter.on(",").omitEmptyStrings().trimResults().split(str).forEach(System.out::println);
// 固定长度分割 fixedLength
System.out.println("----");
Splitter.on(",").fixedLength(5).split(str).forEach(System.out::println);
// 指定长度分割
System.out.println("----");
Splitter.on(",").limit(2).split(str).forEach(System.out::println);
// 转Map
System.out.println("----");
String new_str = "1:haha,2:hehe";
Map<String,String> map = Splitter.on(",").withKeyValueSeparator(":").split(new_str);
System.out.println(map.get("1"));
}

7、差集、并集、交集


@Test
public void test3(){
    Set<String> set1 = new HashSet<>();
set1.add("set1");
Set<String> set2 = new HashSet<>();
set2.add("set2");
set2.add("uuu");
// 求差集，set2与set1之间的差集
Sets.SetView<String> difference = Sets.difference(set2,set1);
System.out.println(difference);
// intersection 交集
    // union 并集
}