Question

我用数组填充数组列表。每行都是具有属性的项目。现在我想通过一个属性对项目进行排序，并将它们“打印”到textview。

ArrayList<String[]> arrayList = new ArrayList<String[]>();
final String[] rowToArray = new String[7];
rowToArray[0] = itemName;
rowToArray[1] = itemProperties1;
rowToArray[2] = itemProperties2;
rowToArray[3] = itemProperties3;
rowToArray[4] = itemProperties4;
rowToArray[5] = itemProperties5;
rowToArray[6] = itemProperties6;
arrayList.add(rowToArray);

你能帮我按属性对它进行排序，然后告诉我如何用属性逐个打印项目。

提前谢谢。

修改

已解决ppeterka66

我只需要添加他的代码并调用 Collections.sort（arrayList，new StringArrayComparator（column））; 其中列是必需列的排序。

int i=0;
final int column=2;
Collections.sort(arrayList,new StringArrayComparator(column));
for(String[] line :arrayList) 
    {
    Log.d(Integer.toString(i),line[column].toString());
    }

Answer 1

Collections.sort

例如

class User {

    String name;
    String age;

    public User(String name, String age) {
        this.name = name;
        this.age = age;
    }

    public String getAge() {
        return age;
    }

    public void setAge(String age) {
        this.age = age;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }
}
import java.util.Comparator;

public class ComparatorUser implements Comparator {

    public int compare(Object arg0, Object arg1) {
        User user0 = (User) arg0;
        User user1 = (User) arg1;

        int flag = user0.getAge().compareTo(user1.getAge());
        if (flag == 0) {
            return user0.getName().compareTo(user1.getName());
        } else {
            return flag;
        }
    }

}
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;

public class SortTest {

    public static void main(String[] args) {
        List userlist = new ArrayList();
        userlist.add(new User("dd", "4"));
        userlist.add(new User("aa", "1"));
        userlist.add(new User("ee", "5"));
        userlist.add(new User("bb", "2"));
        userlist.add(new User("ff", "5"));
        userlist.add(new User("cc", "3"));
        userlist.add(new User("gg", "6"));

        ComparatorUser comparator = new ComparatorUser();
        Collections.sort(userlist, comparator);

        for (int i = 0; i < userlist.size(); i++) {
            User user_temp = (User) userlist.get(i);
            System.out.println(user_temp.getAge() + "," + user_temp.getName());
        }

    }
}

Answer 2

您可以创建一个可重用的String [] Comparator，您可以指定要比较数组的索引：

public class StringArrayComparator implements Comparator<String[]> {
  //we store the index to compare the arrays by in this instance variable
  private final int stringIndexToCompare;

  //constructor accepting the value for the index to check
  public StringArrayComparator(int whichString) {
    stringIndexToCompare=whichString;
  }

  @Override
  public int compare(String[] o1, String[] o2) {
    //checking if any of the arrays is null
    if(o1==null)      { return o2==null?0:1; } //if o1 is null, o2 determines the resuult
    else if(o2==null) { return -1; } //this only gets evaluated if o1 is not null

    //get the strings, by checking if the arrays are long enough
    String first = o1.length>stringIndexToCompare?o1[stringIndexToCompare]:null;
    String second= o2.length>stringIndexToCompare?o2[stringIndexToCompare]:null;

    //null checking the strings themselves -- basically same as above
    if(first==null)          { return second==null?0:1; }
    else if(second==null)    { return -1; }

    //if both non-null, compare them.
    return first.compareTo(second);
  }
}

要在您的列表中使用：

Collections.sort(myList,new StringArrayComparator(3));

注意：3指定要比较的数组的索引。

您没有指定打印字符串外观的预期输出，但只是打印列表，您可以使用此oneliner：

  System.out.println(Arrays.deepToString(a.toArray()));

修改

我希望看到类似Log.d（“行号”，列[0] +“，”+列1 +“，”+列[2] + ...）; < / p>

嘿，看起来几乎没问题......基本上你只需要把它放到一个循环中：这会逐行打印出来：

int lineNo=0; for(String[] line :myList) { StringBuilder sb = new StringBuilder(); sb.append(++i); //line number, incrementing too //iterating through the elements of the array for(int col=0;col<line.lenght;col++) { sb.append(","); if(line[col]!=null) { //check for null.... sb.append(line[col]); } } Log.d(sb.toString()); //append the value from the builder to the log. }

将它放在一个大字符串中：

int lineNo=0; StringBuilder sb = new StringBuilder(); //create it here for(String[] line :myList) { sb.append(++i); //line number, incrementing too //iterating through the elements of the array for(int col=0;col<line.lenght;col++) { sb.append(","); if(line[col]!=null) { //check for null.... sb.append(line[col]); } } sb.append("\n"); //append line break } Log.d(sb.toString()); //append the value from the builder to the log.

或者，为此目的使用String.format（）可能会更好（虽然更慢），这样可以提供更好的格式：

//assembly format string //if no line number was needed: String format = ""; String format = "%d"; //line number, %d means integer for(int i=0;i<7;i++) { format+=",%20s"; //%20s means left aligned, 20 wide string } format += "\n"; //line break; int lineNumber=0; for(String[] line:myArray) { //if you didn't need the line number, it would be so easy here //String.format(format,line); //one line, but this doesn't have the line number yet... //with line numbers: int iamLazyNow = 0; String formatted = String.format(format,++lineNumber, line[iamLazyNow++], line[iamLazyNow++], line[iamLazyNow++], line[iamLazyNow++], line[iamLazyNow++], line[iamLazyNow++], line[iamLazyNow++]); //practically one line, but ugly //you can append formatted to a StringBuilder, or print it here... }

按任何列排序ArrayList <string []>并“打印”结果</string []>

2 个答案: