Java array list map between the introduction of the three
- 2020-04-01 02:22:17
- OfStack
The relationship between the three is transformed, and a picture is clearly presented.
< img SRC = "border = 0 / / files.jb51.net/file_images/article/201310/201310291116471.gif? 201392911179 ">
The code:
Maputils is an apache collection package.
< img SRC = "border = 0 / / files.jb51.net/file_images/article/201310/201310291116471.gif? 201392911179 ">
The code:
Maputils is an apache collection package.
package util;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import org.apache.commons.collections.MapUtils;
public class Convert {
public static void main(String[] args) {
//1. Convert the array to list and map
String[] arr = {"123","456","789","123"};
List<String> list = Arrays.asList(arr);
//The array is converted to map. When the array is one-dimensional, the odd number is key, the even number is value, the odd number of elements, and the last one is discarded
//. Two dimensional arrays as two one-dimensional arrays
Map map = MapUtils.putAll(new HashMap(), arr);
String[][] ss = {{"a","b","e"},{"c","d","f"}};
MapUtils.debugPrint(System.out,arr,map);
MapUtils.putAll(map, arr);
MapUtils.debugPrint(System.out,arr,map);
MapUtils.putAll(map, ss);
MapUtils.verbosePrint(System.out,arr,MapUtils.invertMap(map));
//List is converted to arr
List<String> ls = new ArrayList<String>();
ls.add("wch");
ls.add("name");
String[] as = (String[]) ls.toArray();
}
}