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在这里插入代码片

List> listMaps = new ArrayList>();
Map map1 = new HashMap();
map1.put(“aaa”, “111”);
map1.put(“bbb”, “222”);
map1.put(“ccc”, “333”);
listMaps.add(map1);

        for (Map map : Maps) {
            for (String s : map.keySet()) {
                System.out.print(map.get(s) + "  ");
            }
        }
        System.out.println();
        System.out.println("-----------------------------");


        for (int i = 0; i < Maps.size(); i++) {
            Map map = Maps.get(i);
            Iterator iterator = map.keySet().iterator();
            while (iterator.hasNext()) {
                String string = (String) iterator.next();
                System.out.println(map.get(string));
            }
        }
        System.out.println("-----------------------------");


        for (Map map : listMaps) {
            for (Map.Entry m : map.entrySet()) {
                System.out.print(m.getKey() + "    ");
                System.out.println(m.getValue());
            }
        }
        System.out.println("-----------------------------");

public static void main(String[] args) {
List list = new ArrayList<>();
for (int i = 1; i < 10; i++) {
list.add(i);
}

Collections.shuffle(list);
System.out.println(list);

Integer max = Collections.max(list);

System.out.println(max);

Integer min = Collections.min(list);

System.out.println(min);

Collections.sort(list);
System.out.println(list);

Collections.swap(list,0,1);
System.out.println(list);

List list1 = new ArrayList<>();

for (int i = 0; i < 9; i++) {
list1.add(1);
}

Collections.copy(list1,list);
System.out.println(list1);

}

public static void main(String[] args) {
int num = 5;// ArithmeticException 算数异常
int a= num / 0;
System.out.println(a);
int[] arr = new int[2];
arr[4] = 0; // ArrayIndexOutOfBoundsException 数组下标越界异常
arr = null;
int length = arr.length; // NullPointerException 空指针异常
A a1 = new B();
C c = ©a1; // ClassCastException 类型转换异常
//NumberFormatException 数字格式异常
int abc = Integer.parseInt(“abc”);
System.out.println();
String str = “a”;
for (int i = 0; i < 100000; i++) {// OutOfMemoryError 内存溢出错误
str = str + str;
}
System.out.println(str);
}
}
class A {}
class B extends A{}
class C extends B{}

mport java.util.Map.Entry;
import java.util.TreeMap;

public class zy04 {

    public static void main(String[] args) {
        String st="If you want to change your fate I think you must come to the ujiuye to learn java";
        String []sts=st.split(" ");
        TreeMapmap=new TreeMap<>();
        for(String string:sts){
            map.put(string, map.containsKey(string)?map.get(string)+1:1);
        }
        for(Entry entry:map.entrySet()){
            System.out.println(entry.getKey()+"="+entry.getValue());
        }
    }
}