arraylist | 易学教程

Print out ArrayList content in Android TableLayout

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问题 I have this ArrayList: ArrayList<Double> debtList = datasource.debtList; ArrayList<Double> feeList = datasource.feeList; How would I print out these two Lists side by side (formatting doesn't matter) in a TableLayout in a loop? Here is layout: TableLayout table = (TableLayout) findViewById(R.id.myTableLayout); 回答1: Ok, you have two arraylists debtList and feeList, I assume both the arraylist contains equal number of elements, now iterate through this list, Create Table Row add two textViews

Adding comma separated strings to an ArrayList and vice versa

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问题 How to add a comma separated string to an ArrayList? My string "returnedItems" could hold 1 or 20 items which I'd like to add to my ArrayList "selItemArrayList". After the ArrayList has been populated, I'd like to later iterate through it and format the items into a comma separated string with no spaces between the items. 回答1: String returnedItems = "a,b,c"; List<String> sellItems = Arrays.asList(returnedItems.split(",")); Now iterate over the list and append each item to a StringBuilder:

C# objects in arrayLists

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问题 I'm working with ArrayList in C# and I am wondering how I can add objects to an ArrayList and then retrieve the values from it? In short, how can I add, delete, edit and read from an ArrayList containing objects of classes? Thankful for all help! 回答1: Unless you are in a situation where you must use .NET 1.0/1.1, or need to interact with legacy code that uses ArrayList - you should really avoid using ArrayLists in new code. Use the generic collection type List<> instead. The operations to add

Dynamic initialization of ArrayList<anyClassObject>

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问题 Normally if we want to initialize a generic non-primitive ArrayList we do this ArrayList<?> arrayList = new ArrayList<MyClass.class>(); But I want to do something similar to this no matter which class object I pass, i.e private void getModel(Class responseType){ //Something similar, because this does not work.. ArrayList<?> arrayList = new ArrayList<responseType>(); } Any Help would be greatly appreciated. 回答1: Try something like this private <T> void setModel(Class<T> type) { ArrayList<T>

Circular ArrayList (extending ArrayList)

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问题 So my program has a need of a type of circular ArrayList. Only circular thing about it has to be the get(int index) method, this is the original: /** * Returns the element at the specified position in this list. * * @param index index of the element to return * @return the element at the specified position in this list * @throws IndexOutOfBoundsException {@inheritDoc} */ public E get(int index) { rangeCheck(index); return elementData(index); } If index is -1 it should get the element with

Circular ArrayList (extending ArrayList)

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How can I retrieve a JDBC ResultSet as an ArrayList?

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问题 I'm doing a query to retrieve a large amount of IDs (integers). Instead of iterating millions of times through the ResultSet and copying everything one-by-one to an ArrayList, is there some way to simply retrieve everything as an ArrayList? I understand that ResultSet is supposed to be iterated because the underlying implementation may be caching stuff, but in my situation I just need all the IDs straight away. I know I can set the FetchSize to a large number, but then I still have to

ArrayList<String> to CharSequence[]

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问题 What would be the easiest way to make a CharSequence[] out of ArrayList<String> ? Sure I could iterate through every ArrayList item and copy to CharSequence array, but maybe there is better/faster way? 回答1: You can use List#toArray(T[]) for this. CharSequence[] cs = list.toArray(new CharSequence[list.size()]); Here's a little demo: List<String> list = Arrays.asList("foo", "bar", "waa"); CharSequence[] cs = list.toArray(new CharSequence[list.size()]); System.out.println(Arrays.toString(cs)); /

why HashMap Values are not cast in List?

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问题 I'm putting values into the hashmap which is of the form, Map<Long, Double> highLowValueMap=new HashMap<Long, Double>(); highLowValueMap.put(1l, 10.0); highLowValueMap.put(2l, 20.0); I want to create a list by using values() method of map. List<Double> valuesToMatch=new ArrayList<>(); valuesToMatch=(List<Double>) highLowValueMap.values(); or List<Double> valuesToMatch=(List<Double>) highLowValueMap.values(); However, it throws an exception: Exception in thread "main" java.lang

java基础小练习,1-打印一百次(1~10)的随机数,2-固定一个随机数(1~100)，然后猜出他,3-定义以指定格式打印集合(ArrayList类型作为参数)，使用{}括起来，使用@代替,分隔每个元素

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推荐自己码一下，可以使用别的方法，面向对象，不需要注重过程 /* 题目:我需要打印一百次(1~10)的随机数 */ import java.util.Random; public class demo02Scannersum { public static void main(String[] args) { Random r = new Random(); for (int i = 0; i < 100; i++) { int num = r.nextInt(10)+1; System.out.println(num+" "); } } } /* 题目:固定一个随机数(1~100)，然后猜出他 */ import java.util.Random; import java.util.Scanner; public class demo02Scannersum { public static void main(String[] args) { Random r = new Random(); int rr = r.nextInt(100) + 1; Scanner s = new Scanner(System.in); System.out.println("这是一个测试欧气的游戏，我会随机选取1~100的一个数，猜中它，次数用的越少的代表越欧"); int result=1;