For循环输出列表的内容:

List<String> myList = new ArrayList<String>();
myList.add("AA");
myList.add("BB");

for ( String elem : myList ) {
  System.out.println("Element : "+elem);
}

结果:

Element : AA
Element : BB

如果你想打印在单行(只是为了信息):

String strList = String.join(", ", myList);
System.out.println("Elements : "+strList);

结果:

Elements : AA, BB

我写了一个转储函数，它基本上打印出对象的公共成员，如果它没有覆盖toString()。可以很容易地将其扩展为调用getter。 Javadoc:

将给定对象转储到系统。Out，使用以下规则: 如果对象是Iterable，则它的所有组件都将被转储。 如果Object或它的一个超类覆盖了toString()，则“toString”将被转储 否则，该方法将为对象的所有公共成员递归调用

/**
 * Dumps an given Object to System.out, using the following rules:<br>
 * <ul>
 * <li> If the Object is {@link Iterable}, all of its components are dumped.</li>
 * <li> If the Object or one of its superclasses overrides {@link #toString()}, the "toString" is dumped</li>
 * <li> Else the method is called recursively for all public members of the Object </li>
 * </ul>
 * @param input
 * @throws Exception
 */
public static void dump(Object input) throws Exception{
    dump(input, 0);
}

private static void dump(Object input, int depth) throws Exception{
    if(input==null){
        System.out.print("null\n"+indent(depth));
        return;
    }

    Class<? extends Object> clazz = input.getClass();
    System.out.print(clazz.getSimpleName()+" ");
    if(input instanceof Iterable<?>){
        for(Object o: ((Iterable<?>)input)){
            System.out.print("\n"+indent(depth+1));
            dump(o, depth+1);
        }
    }else if(clazz.getMethod("toString").getDeclaringClass().equals(Object.class)){
        Field[] fields = clazz.getFields();
        if(fields.length == 0){
            System.out.print(input+"\n"+indent(depth));
        }
        System.out.print("\n"+indent(depth+1));
        for(Field field: fields){
            Object o = field.get(input);
            String s = "|- "+field.getName()+": ";
            System.out.print(s);
            dump(o, depth+1);
        }
    }else{

        System.out.print(input+"\n"+indent(depth));
    }
}

private static String indent(int depth) {
    StringBuilder sb = new StringBuilder();
    for(int i=0; i<depth; i++)
        sb.append("  ");
    return sb.toString();
}

java 11问题的解决方案是:

String separator = ", ";
String toPrint = list.stream().map(o -> String.valueOf(o)).collect(Collectors.joining(separator));

System.out.println(toPrint);

从Java 8开始，List继承了一个默认的“forEach”方法，你可以将它与方法引用“System”结合起来使用。输出::println”像这样:

list.forEach(System.out::println);

你可以试试:

2D(或以上) System.out.println (Arrays.deepToString (list.toArray ())); 1 d System.out.println (Arrays.toString (list.toArray ()))

我也遇到过类似的问题。我的代码:

List<Integer> leaveDatesList = new ArrayList<>();

.....inserted value in list.......

方法1:在for循环中打印一个列表

for(int i=0;i<leaveDatesList.size();i++){
    System.out.println(leaveDatesList.get(i));
}

方法2:在forEach中打印列表，for循环

for(Integer leave : leaveDatesList){
    System.out.println(leave);
}

方法3:在java 8中打印列表

leaveDatesList.forEach(System.out::println);