Task: Align columns




Go: package main

import (
    "fmt"
    "strings"
)

const text = `Given$a$text$file$of$many$lines,$where$fields$within$a$line$
are$delineated$by$a$single$'dollar'$character,$write$a$program
that$aligns$each$column$of$fields$by$ensuring$that$words$in$each$
column$are$separated$by$at$least$one$space.
Further,$allow$for$each$word$in$a$column$to$be$either$left$
justified,$right$justified,$or$center$justified$within$its$column.`

type formatter struct {
    text  [][]string
    width []int
}

func newFormatter(text string) *formatter {
    var f formatter
    for _, line := range strings.Split(text, "\n") {
        words := strings.Split(line, "$")
        for words[len(words)-1] == "" {
            words = words[:len(words)-1]
        }
        f.text = append(f.text, words)
        for i, word := range words {
            if i == len(f.width) {
                f.width = append(f.width, len(word))
            } else if len(word) > f.width[i] {
                f.width[i] = len(word)
            }
        }
    }
    return &f
}

const (
    left = iota
    middle
    right
)

func (f formatter) print(j int) {
    for _, line := range f.text {
        for i, word := range line {
            fmt.Printf("%-*s ", f.width[i], fmt.Sprintf("%*s",
                len(word)+(f.width[i]-len(word))*j/2, word))
        }
        fmt.Println("")
    }
    fmt.Println("")
}

func main() {
    f := newFormatter(text)
    f.print(left)
    f.print(middle)
    f.print(right)
}


Java: import java.io.IOException;
import java.nio.charset.StandardCharsets;
import java.nio.file.Files;
import java.nio.file.Paths;
import java.util.ArrayList;
import java.util.List;

import org.apache.commons.lang3.StringUtils;


public class ColumnAligner {
    private List<String[]> words = new ArrayList<>();
    private int columns = 0;
    private List<Integer> columnWidths = new ArrayList<>();

    
    public ColumnAligner(String s) {
        String[] lines = s.split("\\n");
        for (String line : lines) {
            processInputLine(line);
        }
    }

    
    public ColumnAligner(List<String> lines) {
        for (String line : lines) {
            processInputLine(line);
        }
    }

    private void processInputLine(String line) {
        String[] lineWords = line.split("\\$");
        words.add(lineWords);
        columns = Math.max(columns, lineWords.length);
        for (int i = 0; i < lineWords.length; i++) {
            String word = lineWords[i];
            if (i >= columnWidths.size()) {
                columnWidths.add(word.length());
            } else {
                columnWidths.set(i, Math.max(columnWidths.get(i), word.length()));
            }
        }
    }

    interface AlignFunction {
        String align(String s, int length);
    }

    
    public String alignLeft() {
        return align(new AlignFunction() {
            @Override
            public String align(String s, int length) {
                return StringUtils.rightPad(s, length);
            }
        });
    }

    
    public String alignRight() {
        return align(new AlignFunction() {
            @Override
            public String align(String s, int length) {
                return StringUtils.leftPad(s, length);
            }
        });
    }

    
    public String alignCenter() {
        return align(new AlignFunction() {
            @Override
            public String align(String s, int length) {
                return StringUtils.center(s, length);
            }
        });
    }

    private String align(AlignFunction a) {
        StringBuilder result = new StringBuilder();
        for (String[] lineWords : words) {
            for (int i = 0; i < lineWords.length; i++) {
                String word = lineWords[i];
                if (i == 0) {
                    result.append("|");
                }
                result.append(a.align(word, columnWidths.get(i)) + "|");
            }
            result.append("\n");
        }
        return result.toString();
    }

    public static void main(String args[]) throws IOException {
        if (args.length < 1) {
            System.out.println("Usage: ColumnAligner file [left|right|center]");
            return;
        }
        String filePath = args[0];
        String alignment = "left";
        if (args.length >= 2) {
            alignment = args[1];
        }
        ColumnAligner ca = new ColumnAligner(Files.readAllLines(Paths.get(filePath), StandardCharsets.UTF_8));
        switch (alignment) {
        case "left":
            System.out.print(ca.alignLeft());
            break;
        case "right":
            System.out.print(ca.alignRight());
            break;
        case "center":
            System.out.print(ca.alignCenter());
            break;
        default:
            System.err.println(String.format("Error! Unknown alignment: '%s'", alignment));
            break;
        }
    }
}