https://github.com/google/guava/guava: Guava is a suite of core and expanded libraries that include utility classes, google's collections, io classes, and much much more. 
public final class com.google.common.io.LineReader
  minor version: 0
  major version: 59
  flags: flags: (0x0031) ACC_PUBLIC, ACC_FINAL, ACC_SUPER
  this_class: com.google.common.io.LineReader
  super_class: java.lang.Object
{
  private final java.lang.Readable readable;
    descriptor: Ljava/lang/Readable;
    flags: (0x0012) ACC_PRIVATE, ACC_FINAL

  private final java.io.Reader reader;
    descriptor: Ljava/io/Reader;
    flags: (0x0012) ACC_PRIVATE, ACC_FINAL
    RuntimeVisibleTypeAnnotations: 
      FIELD
        org.checkerframework.checker.nullness.qual.Nullable()

  private final java.nio.CharBuffer cbuf;
    descriptor: Ljava/nio/CharBuffer;
    flags: (0x0012) ACC_PRIVATE, ACC_FINAL

  private final char[] buf;
    descriptor: [C
    flags: (0x0012) ACC_PRIVATE, ACC_FINAL

  private final java.util.Queue<java.lang.String> lines;
    descriptor: Ljava/util/Queue;
    flags: (0x0012) ACC_PRIVATE, ACC_FINAL
    Signature: Ljava/util/Queue<Ljava/lang/String;>;

  private final com.google.common.io.LineBuffer lineBuf;
    descriptor: Lcom/google/common/io/LineBuffer;
    flags: (0x0012) ACC_PRIVATE, ACC_FINAL

  public void <init>(java.lang.Readable);
    descriptor: (Ljava/lang/Readable;)V
    flags: (0x0001) ACC_PUBLIC
    Code:
      stack=4, locals=2, args_size=2
        start local 0 // com.google.common.io.LineReader this
        start local 1 // java.lang.Readable readable
         0: .line 56
            aload 0 /* this */
            invokespecial java.lang.Object.<init>:()V
         1: .line 43
            aload 0 /* this */
            invokestatic com.google.common.io.CharStreams.createBuffer:()Ljava/nio/CharBuffer;
            putfield com.google.common.io.LineReader.cbuf:Ljava/nio/CharBuffer;
         2: .line 44
            aload 0 /* this */
            aload 0 /* this */
            getfield com.google.common.io.LineReader.cbuf:Ljava/nio/CharBuffer;
            invokevirtual java.nio.CharBuffer.array:()[C
            putfield com.google.common.io.LineReader.buf:[C
         3: .line 46
            aload 0 /* this */
            new java.util.LinkedList
            dup
            invokespecial java.util.LinkedList.<init>:()V
            putfield com.google.common.io.LineReader.lines:Ljava/util/Queue;
         4: .line 47
            aload 0 /* this */
         5: .line 48
            new com.google.common.io.LineReader$1
            dup
            aload 0 /* this */
            invokespecial com.google.common.io.LineReader$1.<init>:(Lcom/google/common/io/LineReader;)V
            putfield com.google.common.io.LineReader.lineBuf:Lcom/google/common/io/LineBuffer;
         6: .line 57
            aload 0 /* this */
            aload 1 /* readable */
            invokestatic com.google.common.base.Preconditions.checkNotNull:(Ljava/lang/Object;)Ljava/lang/Object;
            checkcast java.lang.Readable
            putfield com.google.common.io.LineReader.readable:Ljava/lang/Readable;
         7: .line 58
            aload 0 /* this */
            aload 1 /* readable */
            instanceof java.io.Reader
            ifeq 8
            aload 1 /* readable */
            checkcast java.io.Reader
            goto 9
      StackMap locals: com.google.common.io.LineReader java.lang.Readable
      StackMap stack: com.google.common.io.LineReader
         8: aconst_null
      StackMap locals: com.google.common.io.LineReader java.lang.Readable
      StackMap stack: com.google.common.io.LineReader java.io.Reader
         9: putfield com.google.common.io.LineReader.reader:Ljava/io/Reader;
        10: .line 59
            return
        end local 1 // java.lang.Readable readable
        end local 0 // com.google.common.io.LineReader this
      LocalVariableTable:
        Start  End  Slot      Name  Signature
            0   11     0      this  Lcom/google/common/io/LineReader;
            0   11     1  readable  Ljava/lang/Readable;
    MethodParameters:
          Name  Flags
      readable  

  public java.lang.String readLine();
    descriptor: ()Ljava/lang/String;
    flags: (0x0001) ACC_PUBLIC
    Code:
      stack=4, locals=2, args_size=1
        start local 0 // com.google.common.io.LineReader this
         0: .line 72
            goto 9
         1: .line 73
      StackMap locals:
      StackMap stack:
            aload 0 /* this */
            getfield com.google.common.io.LineReader.cbuf:Ljava/nio/CharBuffer;
            invokevirtual java.nio.CharBuffer.clear:()Ljava/nio/Buffer;
            pop
         2: .line 76
            aload 0 /* this */
            getfield com.google.common.io.LineReader.reader:Ljava/io/Reader;
            ifnull 3
            aload 0 /* this */
            getfield com.google.common.io.LineReader.reader:Ljava/io/Reader;
            aload 0 /* this */
            getfield com.google.common.io.LineReader.buf:[C
            iconst_0
            aload 0 /* this */
            getfield com.google.common.io.LineReader.buf:[C
            arraylength
            invokevirtual java.io.Reader.read:([CII)I
            goto 4
      StackMap locals:
      StackMap stack:
         3: aload 0 /* this */
            getfield com.google.common.io.LineReader.readable:Ljava/lang/Readable;
            aload 0 /* this */
            getfield com.google.common.io.LineReader.cbuf:Ljava/nio/CharBuffer;
            invokeinterface java.lang.Readable.read:(Ljava/nio/CharBuffer;)I
      StackMap locals:
      StackMap stack: int
         4: istore 1 /* read */
        start local 1 // int read
         5: .line 77
            iload 1 /* read */
            iconst_m1
            if_icmpne 8
         6: .line 78
            aload 0 /* this */
            getfield com.google.common.io.LineReader.lineBuf:Lcom/google/common/io/LineBuffer;
            invokevirtual com.google.common.io.LineBuffer.finish:()V
         7: .line 79
            goto 10
         8: .line 81
      StackMap locals: int
      StackMap stack:
            aload 0 /* this */
            getfield com.google.common.io.LineReader.lineBuf:Lcom/google/common/io/LineBuffer;
            aload 0 /* this */
            getfield com.google.common.io.LineReader.buf:[C
            iconst_0
            iload 1 /* read */
            invokevirtual com.google.common.io.LineBuffer.add:([CII)V
        end local 1 // int read
         9: .line 72
      StackMap locals:
      StackMap stack:
            aload 0 /* this */
            getfield com.google.common.io.LineReader.lines:Ljava/util/Queue;
            invokeinterface java.util.Queue.peek:()Ljava/lang/Object;
            ifnull 1
        10: .line 83
      StackMap locals:
      StackMap stack:
            aload 0 /* this */
            getfield com.google.common.io.LineReader.lines:Ljava/util/Queue;
            invokeinterface java.util.Queue.poll:()Ljava/lang/Object;
            checkcast java.lang.String
            areturn
        end local 0 // com.google.common.io.LineReader this
      LocalVariableTable:
        Start  End  Slot  Name  Signature
            0   11     0  this  Lcom/google/common/io/LineReader;
            5    9     1  read  I
    Exceptions:
      throws java.io.IOException
    RuntimeInvisibleAnnotations: 
      com.google.errorprone.annotations.CanIgnoreReturnValue()
}
SourceFile: "LineReader.java"
NestMembers:
  com.google.common.io.LineReader$1
InnerClasses:
  com.google.common.io.LineReader$1
    RuntimeInvisibleAnnotations: 
      com.google.common.annotations.Beta()
      com.google.common.annotations.GwtIncompatible()