如何按条件从数组中获取对象？

Question

这是我的实际代码：

public TerminalGui[] getTerminalGuis() {
    Components comps[] = this.getComponents();
    int i, j = 0;

    for( i = 0; i < comps.length ; i++ ) {
        if( comps[i] instanceof TerminalGui ) {
            j++;
        }
    }

    TerminalGui terminalGuis[j];
    int k = 0;
    for( Component c : comps ) {
        if( c instanceof TerminalGui ) {
            terminalGuis[k] = c;
            k++;
        }
    }
    return terminalGuis;
}

如何做得更好？我想从this.getComponents() 获取所有对象，它们是TerminalGui（接口）的实例。

Answer 1

我会这样做：

public TerminalGui[] getTerminalGuis() {
    Components comps[] = getComponents();
    List<TerminalGui> list = new ArrayList<TerminalGui>();

    if (comps == null) return null;

    for( Component c : comps ) {
        if( c instanceof TerminalGui ) {
            list.add(c);
        }
    }

    return list.toArray(new TerminalGui[list.size()]);
}

Answer 2

@NikolayKuznetsov 的答案最好是最少的代码。但在这里你的版本更正了。所以你认识到了可能性。

public TerminalGui[] getTerminalGuis() {
    Component[] comps = this.getComponents();
    int j = 0;
    for (int i = 0; i < comps.length; i++) {
        if (comps[i] instanceof TerminalGui) {
            j++;
        }
    }

    TerminalGui[] terminalGuis = new TerminalGui[j];
    int k = 0;
    for (Component c : comps) {
        if (c instanceof TerminalGui) {
            terminalGuis[k] = c;
            k++;
        }
    }
    return terminalGuis;
}

Answer 3

您可以使用List

public TerminalGui[] getTerminalGuis() {
   Components comps[] = this.getComponents();
   List<TerminalGui> terminals = new ArrayList<TerminalGui>();
   int i;

      for( i = 0; i < comps.length ; ++i ) {
         if( comps[i] instanceof TerminalGui ) {
             terminals.add(comps[i]);
         }
      }
   return terminals.toArray(new TerminalGui[terminals.size()])

}