java - 变量在方法中定义了 2 次

Question

当我想到这个方法时，我正在审查 com.google.android.material.tabs.Tablayout 中的一些方法:

private static ColorStateList createColorStateList(int defaultColor, int selectedColor) {
    int[][] states = new int[2][];
    int[] colors = new int[2];
    int i = 0;
    states[i] = SELECTED_STATE_SET;
    colors[i] = selectedColor;
    int i = i + 1;
    states[i] = EMPTY_STATE_SET;
    colors[i] = defaultColor;
    ++i;
    return new ColorStateList(states, colors);
}

How this method could be compiled with variable i being defined 2 times? It is part of the library everyone use.

Answer 1

其实不是这样的。

您正在 checkin 反编译的 TabLayout.class 文件

private static ColorStateList createColorStateList(int defaultColor, int selectedColor) {
        int[][] states = new int[2][];
        int[] colors = new int[2];
        int i = 0;
        states[i] = SELECTED_STATE_SET;
        colors[i] = selectedColor;
        int i = i + 1;
        states[i] = EMPTY_STATE_SET;
        colors[i] = defaultColor;
        ++i;
        return new ColorStateList(states, colors);
    }

但是，如果您 checkin 源文件 TabLayout.java，您将获得如下代码。

  private static ColorStateList createColorStateList(int defaultColor, int selectedColor) {
    final int[][] states = new int[2][];
    final int[] colors = new int[2];
    int i = 0;

    states[i] = SELECTED_STATE_SET;
    colors[i] = selectedColor;
    i++;

    // Default enabled state
    states[i] = EMPTY_STATE_SET;
    colors[i] = defaultColor;
    i++;

    return new ColorStateList(states, colors);
  }