例で考えるJavaプログラミング (4)

progJ.pdf 記事一覧

List のサブクラス Que のメソッド

progJ.pdf に [#30] ～ [#37] を追加しました．

補足：(1) P34.java
public class P34{
  public static void main(String[] args) {
    String s = "-123"; int k;
    k = Integer.parseInt(s);
    s = Double.toString(k + 4.5);
    System.out.println(k + ", " + s);
    //
    //k = Integer.parseInt(" " + s);
    //k = Integer.parseInt(s + ".6");
    System.out.println(s + ", " + k);
    //
    Object obj = k;
    System.out.println(s=Integer.toHexString(k));
    Integer i = new Integer(k);
    System.out.println(i.intValue());
    //System.out.println(k.intValue());
  }
}
(2) P35.java
import java.util.*;
public class P35{
  public static void main(String[ ] args) {
    String s = "123 ＋ 4 ＋ 56 ＋ ＝";
    //
    Que q = new Que( );
    StringTokenizer st = new StringTokenizer(s);
    while(st.hasMoreTokens( )){
      q.insert(st.nextToken( ));
    }
    //
    int x = 0, y = 0; String sq = q.delete( );
    while(sq.charAt(0) != '＝'){
      if(sq.charAt(0) == '＋'){y += x;}
      else{x = Integer.parseInt(sq);}
      sq = q.delete( );
    }
    System.out.println(y);
  }
}
//List.java （デフォルトパッケージ，別ファイル可）
class Cell{
  String d; Cell n;
  Cell(String s){d = s; n = null;}
}
class List{
  Cell top; int sz;
  List(){top = new Cell(" "); sz = 0;}
  void insert(String s, int k){
    if(ksz+1){return;}
    Cell c1 = top, c2 = new Cell(s);
    while(k > 1){c1 = c1.n; k--;}
    if(c1.n != null){c2.n = c1.n;}
    c1.n = c2; sz++;
  }
  void delete(int k){
    if(ksz){return;}
    Cell c1 = top;
    while(k > 1){c1 = c1.n; k--;}
    c1.n = c1.n.n; sz--;
  }
  String show(int k){
    if(ksz){return "?";}
    Cell c1 = top.n; int i = k;
    while(k > 1){c1 = c1.n; k--;}
    System.out.println(i + ": " + c1.d);
    return c1.d;
  }
  void show(){
    Cell c1 = top.n; int i;
    if(sz < 1){System.out.print("empty");}
    for(i = 1; i < sz + 1; i++){     
      System.out.print(c1.d + " ");
      if(i < sz ){c1 = c1.n;}
    }
    System.out.println();
  }
}
class Que extends List{
  Cell last;
  Que( ){ super( ); last = top; }
  void insert(String s){
    last.n = new Cell(s);
    last = last.n; sz++;
  }
  String delete( ){
    Cell c = top.n;
    delete(1); if(sz == 0){last = top;}
    return c.d;
  }
}
(3) P36.java
class Node{
  String d; int ix; Node ln, rn;
  Node(String s, int k){
     d = s; ix = k; ln = rn = null;
  }
}
/* abstract */ class Tree{
  Node root;
  Tree( ){root = new Node("", 0);}
  //abstract void insert(String s, int k);
  //abstract void delete( );
  void show(String s, Node n){
    if(n == null) return;
    show(s+"L", n.ln);
    System.out.println(s + ": " + n.ix + " " + n.d);
    show(s+"R", n.rn);
  }
}
public class P36{
  public static void main(String[ ] args) {
    Tree t = new Tree(); Node rootR = t.root.rn;
    Node tmp; String s = "a";
    tmp = new Node(s, 7); rootR = tmp;
    tmp = new Node(s, 5); rootR.ln = tmp;
    tmp = new Node(s, 9); rootR.rn = tmp;
    tmp = new Node(s, 2); rootR.ln.ln = tmp;
    t.show("", rootR);
  }
}