Java 如何从ArrayList中获取最大值并显示信息
我需要从ArrayList中找到最高的价值(销售额),并显示每个季度哪个商店的销售额最高Java 如何从ArrayList中获取最大值并显示信息,java,Java,我需要从ArrayList中找到最高的价值(销售额),并显示每个季度哪个商店的销售额最高 BufferedReader inputFile = null; PrintWriter outputFile = null; BookStore bs; ArrayList <BookStore> data = new ArrayList(); try { inputFi
BufferedReader inputFile = null;
PrintWriter outputFile = null;
BookStore bs;
ArrayList <BookStore> data = new ArrayList();
try
{
inputFile = new BufferedReader (new FileReader ("bookstoresales.txt"));
outputFile = new PrintWriter (new FileWriter ("bookstoreoutput.txt"));
String indata = null;
while ((indata = inputFile.readLine()) != null)
{
System.out.println (indata);
StringTokenizer st = new StringTokenizer (indata, ",");
String storeBranch = st.nextToken();
String storeAddress = st.nextToken();
double jan = Double.parseDouble (st.nextToken());
double feb = Double.parseDouble (st.nextToken());
double mac = Double.parseDouble (st.nextToken());
double apr = Double.parseDouble (st.nextToken());
double may = Double.parseDouble (st.nextToken());
double jun = Double.parseDouble (st.nextToken());
double jul = Double.parseDouble (st.nextToken());
double aug = Double.parseDouble (st.nextToken());
double sep = Double.parseDouble (st.nextToken());
double oct = Double.parseDouble (st.nextToken());
double nov = Double.parseDouble (st.nextToken());
double dec = Double.parseDouble (st.nextToken());
bs = new BookStore (storeBranch, storeAddress, jan, feb, mac, apr, may, jun, jul, aug, sep, oct, nov, dec);
data.add(bs);
}
outputFile.println ("\n\n=================================== The Highest Bookstore Sales Per Quarter ===================================");
for (int i=0; i<data.size(); i++)
{
//This is where I got stucked.
}
outputFile.println ("\nQuarter 1 : The Highest sales is Bookstores : " + //getbranch name from the highest sales + " with value of + //the highest value");
inputFile.close();
outputFile.close();
}
catch (FileNotFoundException fnf)
{
System.out.println ("File not found!");
}
catch (IOException ioe)
{
System.out.println (ioe.getMessage());
}
}
}
BufferedReader输入文件=null;
PrintWriter outputFile=null;
书店学士;
ArrayList数据=新的ArrayList();
尝试
{
inputFile=new BufferedReader(新文件阅读器(“bookstoresales.txt”);
outputFile=新的PrintWriter(新的FileWriter(“bookstoreautput.txt”);
字符串indata=null;
而((indata=inputFile.readLine())!=null)
{
System.out.println(indata);
StringTokenizer st=新的StringTokenizer(indata,“,”);
字符串storeBranch=st.nextToken();
字符串storeAddress=st.nextToken();
double jan=double.parseDouble(st.nextToken());
double feb=double.parseDouble(st.nextToken());
double mac=double.parseDouble(st.nextToken());
double apr=double.parseDouble(st.nextToken());
double may=double.parseDouble(st.nextToken());
double jun=double.parseDouble(st.nextToken());
double jul=double.parseDouble(st.nextToken());
double-aug=double.parseDouble(st.nextToken());
double sep=double.parseDouble(st.nextToken());
double oct=double.parseDouble(st.nextToken());
double nov=double.parseDouble(st.nextToken());
double dec=double.parseDouble(st.nextToken());
bs=新书店(storeBranch,storeAddress,一月、二月、mac、四月、五月、六月、七月、八月、九月、十月、十一月、十二月);
数据。添加(bs);
}
outputFile.println(“\n\n==========================================================================================================================================================================================================”;
对于(int i=0;i创建一个名为max
的变量。在循环中,如果列表项高于max
,则将max
设置为该项
BookStore max = data.get(0);
for (BookStore bs : data) {
if (bs.sales > max.sales) {
max = bs;
}
}
另一种方法是使用:
使用Java 8:
BookStore max =
data.stream()
.max(Comparator.comparingDouble(bs -> bs.getJan() + ... + bs.getDec()))
.get();
如果你手工做这个,你会怎么做?你会从顶部开始,向下看列表,记住你所见过的最大值。考虑使用数组<代码>双[ ]月=新的双[ 12 ]。
而不是让所有这些双变量都通过了解如何循环数组列表来启动。建议尝试使用资源,而不是手动关闭inputFile和outputFile。此外,bs
可能应该在while循环中声明。BookStore.sales
不是每个季度的总数。这将给出每月最多。
Collections.max(data);
BookStore max =
data.stream()
.max(Comparator.comparingDouble(bs -> bs.getJan() + ... + bs.getDec()))
.get();