org.apache.sqoop.shell.utils.TableDisplayer.java Source code

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Here is the source code for org.apache.sqoop.shell.utils.TableDisplayer.java

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/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.sqoop.shell.utils;

import org.apache.commons.lang.StringUtils;

import java.util.LinkedList;
import java.util.List;

import static org.apache.sqoop.shell.ShellEnvironment.*;

/**
 * Display table based data
 */
public class TableDisplayer {

    /**
     * Display given columns in nice table structure to given IO object.
     *
     * @param headers List of headers
     * @param columns Array of columns
     */
    public static void display(List<String> headers, List<String>... columns) {
        assert headers != null;
        assert columns != null;
        assert headers.size() == columns.length;

        // Count of columns
        int columnCount = headers.size();

        // List of all maximal widths of each column
        List<Integer> widths = new LinkedList<Integer>();
        for (int i = 0; i < columnCount; i++) {
            widths.add(getMaximalWidth(headers.get(i), columns[i]));
        }

        // First line is border
        drawLine(widths);

        // Print out header (text is centralised)
        print("| ");
        for (int i = 0; i < columnCount; i++) {
            print(StringUtils.center(headers.get(i), widths.get(i), ' '));
            print((i == columnCount - 1) ? " |" : " | ");
        }
        println();

        // End up header by border
        drawLine(widths);

        // Number of rows in the table
        int rows = getMaximalRows(columns);

        // Print out each row
        for (int row = 0; row < rows; row++) {
            print("| ");
            for (int i = 0; i < columnCount; i++) {
                print(StringUtils.rightPad(columns[i].get(row), widths.get(i), ' '));
                print((i == columnCount - 1) ? " |" : " | ");
            }
            println();
        }

        // End table by final border
        drawLine(widths);
    }

    /**
     * Draw border line
     *
     * @param widths List of widths of each column
     */
    private static void drawLine(List<Integer> widths) {
        int last = widths.size() - 1;
        print("+-");
        for (int i = 0; i < widths.size(); i++) {
            print(StringUtils.repeat("-", widths.get(i)));
            print((i == last) ? "-+" : "-+-");
        }
        println();
    }

    /**
     * Get maximal width for given column with it's associated header.
     *
     * @param header Associated header
     * @param column All column values
     * @return Maximal
     */
    private static int getMaximalWidth(String header, List<String> column) {
        assert header != null;
        assert column != null;

        int max = header.length();

        for (String value : column) {
            if (value != null && value.length() > max) {
                max = value.length();
            }
        }

        return max;
    }

    /**
     * Get maximal number of rows available in the column list
     *
     * @param columns Array with all column values
     * @return
     */
    private static int getMaximalRows(List<String>... columns) {
        int max = 0;

        for (List<String> column : columns) {
            if (column.size() > max) {
                max = column.size();
            }
        }

        return max;
    }

    private TableDisplayer() {
        // Instantiation is prohibited
    }
}