map.put("a", 100)
map.put("b", 90)
map.put("c", 80)
Set<String>set = map.keySet()
for (String s : set) {
System.out.println(s + "," + map.get(s))
}
public static void main(String[] args) {Integer[] A = {1,2,3,4}
Integer[] B = {1,3,7,9,11}
List<Integer> listA = Arrays.asList(A)
List<Integer> listB = Arrays.asList(B)
List<Integer> jiaoji = new ArrayList<Integer>()
for(Integer a:listA){
if(listB.contains(a)){
jiaoji.add(a)
}
}
System.out.println(jiaoji)
List<Integer> bingji = new ArrayList<Integer>()
for(Integer a:listA){
if(!bingji.contains(a)){
bingji.add(a)
}
}
for(Integer b:listB){
if(!bingji.contains(b)){
bingji.add(b)
}
}
System.out.println(bingji)
List<Integer> chaji = new ArrayList<Integer>()
for(Integer a:listA){
if(!listB.contains(a)){
chaji.add(a)
}
}
System.out.println(chaji)
}
package testimport java.io.BufferedWriter
import java.io.File
import java.io.FileWriter
import java.util.HashMap
import java.util.Iterator
import java.util.Map
import java.util.Map.Entry
public class Test {
public static void main(String[] args) throws Exception {
//创建一个map集合
Map<String, String> map = new HashMap<String, String>()
//香蕉=5.6; 樱桃=25; 桃子=5.6 苹果=2.3
map.put("香蕉", "5.6")
map.put("樱桃", "25")
map.put("桃子", "5.6")
map.put("苹果", "2.3")
System.out.println("map.size = " + map.size())
//遍历该map并且统计出有多少种水果Key用两种方法遍历
System.out.println("方法一:begin")
//遍历map中的键
for (String key : map.keySet()) {
System.out.println("key = " + key)
}
//遍历map中的值
for (String value : map.values()) {
System.out.println("value = " + value)
}
System.out.println("方法一:end")
System.out.println("------------")
System.out.println("方法二:begin")
Iterator<Entry<String, String>> it = map.entrySet().iterator()
while (it.hasNext()) {
Map.Entry<String, String> entry = (Map.Entry<String, String>) it.next()
System.out.println("key="+entry.getKey()+"value="+entry.getValue())
}
System.out.println("方法二:end")
//将香蕉的价格改为10.9
map.put("香蕉", "10.9")
//删除桃子这组数据
map.remove("桃子")
//写入文件
String filePath = Test.class.getClass().getResource("/").getPath()+ "map.txt"
System.out.println(filePath)
File f = new File(filePath)
FileWriter fw = new FileWriter(f)
BufferedWriter bw = new BufferedWriter(fw)
Iterator<Entry<String, String>> it2 = map.entrySet().iterator()
while (it2.hasNext()) {
Map.Entry<String, String> entry = (Map.Entry<String, String>) it2.next()
bw.write(entry.getKey()+"="+entry.getValue()+"元" )
bw.newLine()
}
bw.flush()
bw.close()
fw.close()
}
}
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