org.glassfish.admin.amx.util.LineReaderImpl Maven / Gradle / Ivy

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//Portions Copyright [2018-2019] [Payara Foundation and/or affiliates]

package org.glassfish.admin.amx.util;

import java.io.InputStream;
import java.io.InputStreamReader;

/**
Reads a line from the specified input stream, outputs
the prompt to System.out.
 */
public class LineReaderImpl implements LineReader
{
    private final InputStreamReader mInputStreamReader;

    public LineReaderImpl(InputStream inputStream)
    {
        mInputStreamReader = new InputStreamReader(inputStream);
    }

    @Override
    public String readLine(String prompt) throws java.io.IOException {
        final StringBuilder line = new StringBuilder();

        if (prompt != null)
        {
            System.out.print(prompt);
        }

        while (true)
        {
            final int value = mInputStreamReader.read();
            if (value < 0)
            {
                if (line.length() != 0)
                {
                    // read a line but saw EOF before a newline
                    break;
                }
                return (null);
            }

            final char theChar = (char) value;
            if (theChar == '\n')
            {
                break;
            }

            line.append(theChar);
        }

        return (line.toString().trim());
    }

}