Google Guava封裝類好多好用方法 中文官網：http://ifeve.com/google-guava/

以下舉幾個處理字串與LIST之見，字串與map之見的轉換

import static org.junit.Assert.*;

import java.util.List;
import java.util.Map;

import org.junit.Test;

import com.google.common.base.Joiner;
import com.google.common.base.Splitter;
import com.google.common.collect.Lists;
import com.google.common.collect.Maps;


public class Guava {

        /**
         * list轉換為字串
         */
        @Test
        public void joinTest(){
            List<String> names = Lists.newArrayList("John", "Jane", "Adam", "Tom");
            String result = Joiner.on(",").join(names);
         
            assertEquals(result, "John,Jane,Adam,Tom");
        }


        /**
         * map轉換為字串
         */
        @Test
        public void whenConvertMapToString_thenConverted() {
            Map<String, Integer> salary = Maps.newHashMap();
            salary.put("John", 1000);
            salary.put("Jane", 1500);
            String result = Joiner.on(" , ").withKeyValueSeparator(" = ")
                                            .join(salary);
            System.out.println(result);
        }
        
        /**
         * list轉String，跳過null
         */
        @Test
        public void whenConvertListToStringAndSkipNull_thenConverted() {
            List<String> names = Lists.newArrayList("John", null, "Jane", "Adam", "Tom");
            String result = Joiner.on(",").skipNulls().join(names);
            System.out.println(result);
            assertEquals(result, "John,Jane,Adam,Tom");
        }

        /**
         * list轉String，將null變成其他值
         */
        @Test
        public void whenUseForNull_thenUsed() {
            List<String> names = Lists.newArrayList("John", null, "Jane", "Adam", "Tom");
            String result = Joiner.on(",").useForNull("nameless").join(names);
            System.out.println(result);
            assertEquals(result, "John,nameless,Jane,Adam,Tom");
        }
        
        /**
         * String to List
         */
        @Test
        public void whenCreateListFromString_thenCreated() {
            String input = "apple - banana - orange";
            List<String> result = Splitter.on("-").trimResults().splitToList(input);
            System.out.println(result);
            //assertThat(result, contains("apple", "banana", "orange"));
        }

        /**
         * String to Map
         */
        @Test
        public void whenCreateMapFromString_thenCreated() {
            String input = "John=first,Adam=second";
            Map<String, String> result = Splitter.on(",")
                                                 .withKeyValueSeparator("=")
                                                 .split(input);
         
            assertEquals("first", result.get("John"));
            assertEquals("second", result.get("Adam"));
        }

        /**
         * 多個字元進行分割
         */
        @Test
        public void whenSplitStringOnMultipleSeparator_thenSplit() {
            String input = "apple.banana,,orange,,.";
            List<String> result = Splitter.onPattern("[.|,]")
                                          .omitEmptyStrings()
                                          .splitToList(input);
            System.out.println(result);
        }
        
        /**
         * 每隔多少字元進行分割
         */
        @Test
        public void whenSplitStringOnSpecificLength_thenSplit() {
            String input = "Hello world";
            List<String> result = Splitter.fixedLength(3).splitToList(input);
            System.out.println(result);
        }

        /**
         * 限制分割多少字後停止
         */
        @Test
        public void whenLimitSplitting_thenLimited() {
            String input = "a,b,c,d,e";
            List<String> result = Splitter.on(",")
                                          .limit(4)
                                          .splitToList(input);
         
            assertEquals(4, result.size());
            System.out.println(result);
        }
 



}
 

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