我有两个arrayLists。其中一位列出了在一个州出生的所有总统（列表A）。第二个列表列出了曾经的所有总裁（列表B）。我必须将两者进行比较，并打印出在我们当前任何州都未出生的总统名单。基本上，它们不会出现在列表A中。因此，我必须在列表之间找到所有相同的名称，并将它们从列表B中删除。我该怎么做？
import java.util.*;
import java.io.*;
// NO CMD ARGS - ALL FILENAMES MUST BE HARDOCDED AS I HAVE DONE FOR YOU HERE
public class Potus
{
public static void main( String[] args ) throws Exception
{
BufferedReader infile1 = new BufferedReader( new FileReader("state2Presidents.txt") );
BufferedReader infile2 = new BufferedReader( new FileReader("allPresidents.txt") );
//BufferedReader infile3 = new BufferedReader( new FileReader("allStates.txt") );
HashMap<String,ArrayList<String>> Map = new HashMap<String,ArrayList<String>>();
HashMap<String,String> Maping = new HashMap<String,String>();
ArrayList<String> inverting = new ArrayList<String>();
ArrayList<String> presState = new ArrayList<String>();
String state;
while ((infile1.ready()))
{
ArrayList<String> president = new ArrayList<String>();
state = infile1.readLine();
String [] states = state.split(" ");
for(int i=1; i<states.length; i++)
{
president.add(states[i]);
inverting.add(states[i]);
Maping.put(states[i],states[0]);
}
Map.put(states[0], president);
presState.add(states[0]);
}
Collections.sort(presState);
Collections.sort(inverting);
System.out.println( "The following states had these presidents born in them:\n"); // DO NOT REMOVE OR MODIFY
for(int i=0; i<presState.size(); i++)
{
System.out.print(presState.get(i));
ArrayList<String> value = Map.get(presState.get(i));
for (int j=0; j< value.size() ; j++)
{
System.out.print(" "+value.get(j));
}
System.out.println();
}
System.out.println( "\nList of presidents and the state each was born in:\n"); // DO NOT REMOVE OR MODIFY
for(int i=0; i<inverting.size(); i++)
{
System.out.print(inverting.get(i));
String val = Maping.get(inverting.get(i));
System.out.println(" "+val);
}
System.out.println( "\nThese presidents were born before the states were formed:\n"); // DO NOT REMOVE OR MODIFY
ArrayList<String> america = new ArrayList<String>();
ArrayList<String> am = new ArrayList<String>();
String l;
String line;
while((line = infile2.readLine()) != null)
{
america.add(line);
}
while((l = infile1.readLine()) != null)
{
for(int i=1; i<l.length();i++)
{
am.add(l);
}
}
Collections.sort(america);
Collections.sort(am);
america.removeAll(am);
}
最佳答案
您可以尝试listB.removeAll(listA)