我正在寻找一个实用程序,它将使用正确的列长将矩形String [] []打印到人类可读的表中。
最佳答案
如果您想要类似于MySQL命令行客户端输出的内容,则可以使用以下内容:
import java.io.PrintStream;
import static java.lang.String.format;
import static java.lang.System.out;
public final class PrettyPrinter {
private static final char BORDER_KNOT = '+';
private static final char HORIZONTAL_BORDER = '-';
private static final char VERTICAL_BORDER = '|';
private static final String DEFAULT_AS_NULL = "(NULL)";
private final PrintStream out;
private final String asNull;
public PrettyPrinter(PrintStream out) {
this(out, DEFAULT_AS_NULL);
}
public PrettyPrinter(PrintStream out, String asNull) {
if ( out == null ) {
throw new IllegalArgumentException("No print stream provided");
}
if ( asNull == null ) {
throw new IllegalArgumentException("No NULL-value placeholder provided");
}
this.out = out;
this.asNull = asNull;
}
public void print(String[][] table) {
if ( table == null ) {
throw new IllegalArgumentException("No tabular data provided");
}
if ( table.length == 0 ) {
return;
}
final int[] widths = new int[getMaxColumns(table)];
adjustColumnWidths(table, widths);
printPreparedTable(table, widths, getHorizontalBorder(widths));
}
private void printPreparedTable(String[][] table, int widths[], String horizontalBorder) {
final int lineLength = horizontalBorder.length();
out.println(horizontalBorder);
for ( final String[] row : table ) {
if ( row != null ) {
out.println(getRow(row, widths, lineLength));
out.println(horizontalBorder);
}
}
}
private String getRow(String[] row, int[] widths, int lineLength) {
final StringBuilder builder = new StringBuilder(lineLength).append(VERTICAL_BORDER);
final int maxWidths = widths.length;
for ( int i = 0; i < maxWidths; i++ ) {
builder.append(padRight(getCellValue(safeGet(row, i, null)), widths[i])).append(VERTICAL_BORDER);
}
return builder.toString();
}
private String getHorizontalBorder(int[] widths) {
final StringBuilder builder = new StringBuilder(256);
builder.append(BORDER_KNOT);
for ( final int w : widths ) {
for ( int i = 0; i < w; i++ ) {
builder.append(HORIZONTAL_BORDER);
}
builder.append(BORDER_KNOT);
}
return builder.toString();
}
private int getMaxColumns(String[][] rows) {
int max = 0;
for ( final String[] row : rows ) {
if ( row != null && row.length > max ) {
max = row.length;
}
}
return max;
}
private void adjustColumnWidths(String[][] rows, int[] widths) {
for ( final String[] row : rows ) {
if ( row != null ) {
for ( int c = 0; c < widths.length; c++ ) {
final String cv = getCellValue(safeGet(row, c, asNull));
final int l = cv.length();
if ( widths[c] < l ) {
widths[c] = l;
}
}
}
}
}
private static String padRight(String s, int n) {
return format("%1$-" + n + "s", s);
}
private static String safeGet(String[] array, int index, String defaultValue) {
return index < array.length ? array[index] : defaultValue;
}
private String getCellValue(Object value) {
return value == null ? asNull : value.toString();
}
}
并像这样使用它:
final PrettyPrinter printer = new PrettyPrinter(out);
printer.print(new String[][] {
new String[] {"FIRST NAME", "LAST NAME", "DATE OF BIRTH", "NOTES"},
new String[] {"Joe", "Smith", "November 2, 1972"},
null,
new String[] {"John", "Doe", "April 29, 1970", "Big Brother"},
new String[] {"Jack", null, null, "(yes, no last name)"},
});
上面的代码将产生以下输出:
+----------+---------+----------------+-------------------+
|FIRST NAME|LAST NAME|DATE OF BIRTH |NOTES |
+----------+---------+----------------+-------------------+
|Joe |Smith |November 2, 1972|(NULL) |
+----------+---------+----------------+-------------------+
|John |Doe |April 29, 1970 |Big Brother |
+----------+---------+----------------+-------------------+
|Jack |(NULL) |(NULL) |(yes, no last name)|
+----------+---------+----------------+-------------------+
关于java - 用Java pretty-print 2D数组,我们在Stack Overflow上找到一个类似的问题:https://stackoverflow.com/questions/11383070/