我需要从 for 中实例化和修改视图。是否可以基于 i 获取其中的 ID？

Question

我有以下线性布局：

<?xml version="1.0" encoding="utf-8"?>

<View
    android:id="@+id/white1"
    android:layout_width="8dp"
    android:layout_height="30dp"
    android:layout_marginRight="5dp"
    android:background="@drawable/white_mic_value"/>
<View
    android:id="@+id/white2"
    android:layout_width="8dp"
    android:layout_height="30dp"
    android:layout_marginRight="5dp"
    android:background="@drawable/white_mic_value"/>
<View
    android:id="@+id/white3"
    android:layout_width="8dp"
    android:layout_height="30dp"
    android:layout_marginRight="5dp"
    android:background="@drawable/white_mic_value"/>
<View
    android:id="@+id/white4"
    android:layout_width="8dp"
    android:layout_height="30dp"
    android:layout_marginRight="5dp"
    android:background="@drawable/white_mic_value"/>
<View
    android:id="@+id/white5"
    android:layout_width="8dp"
    android:layout_height="30dp"
    android:layout_marginRight="5dp"
    android:background="@drawable/white_mic_value"/>
<View
    android:id="@+id/white6"
    android:layout_width="8dp"
    android:layout_height="30dp"
    android:layout_marginRight="5dp"
    android:background="@drawable/white_mic_value"/>
<View
    android:id="@+id/white7"
    android:layout_width="8dp"
    android:layout_height="30dp"
    android:layout_marginRight="5dp"
    android:background="@drawable/white_mic_value"/>
<View
    android:id="@+id/white8"
    android:layout_width="8dp"
    android:layout_height="30dp"
    android:layout_marginRight="5dp"
    android:background="@drawable/white_mic_value"/>
<View
    android:id="@+id/white9"
    android:layout_width="8dp"
    android:layout_height="30dp"
    android:layout_marginRight="5dp"
    android:background="@drawable/white_mic_value"/>
<View
    android:id="@+id/white10"
    android:layout_width="8dp"
    android:layout_height="30dp"
    android:layout_marginRight="5dp"
    android:background="@drawable/white_mic_value"/>
<View
    android:id="@+id/white11"
    android:layout_width="8dp"
    android:layout_height="30dp"
    android:layout_marginRight="5dp"
    android:background="@drawable/half_white_mic_value"/>
<View
    android:id="@+id/white12"
    android:layout_width="8dp"
    android:layout_height="30dp"
    android:layout_marginRight="5dp"
    android:background="@drawable/half_white_mic_value"/>
<View
    android:id="@+id/white13"
    android:layout_width="8dp"
    android:layout_height="30dp"
    android:layout_marginRight="5dp"
    android:background="@drawable/half_white_mic_value"/>
<View
    android:id="@+id/white14"
    android:layout_width="8dp"
    android:layout_height="30dp"
    android:layout_marginRight="5dp"
    android:background="@drawable/half_white_mic_value"/>
<View
    android:id="@+id/white15"
    android:layout_width="8dp"
    android:layout_height="30dp"
    android:layout_marginRight="5dp"
    android:background="@drawable/half_white_mic_value"/>
<View
    android:id="@+id/white16"
    android:layout_width="8dp"
    android:layout_height="30dp"
    android:layout_marginRight="5dp"
    android:background="@drawable/half_white_mic_value"/>

我想在 for 中使用它们，例如：

 for(int i= 1 ; i < 17; i++){
     if(soundMeter.getAmplitude() > i*viewThreshold) {
        rootView.findViewById(R.id.white+).setBackgroundResource(R.drawable.white_mic_value);
     }else{
        rootView.findViewById(R.id.white+i).setBackgroundResource(R.drawable.half_white_mic_value);
     }
 }

我试过：int id = getResources().getIdentifier("white" + i, "view", getActivity().getPackageName()); 但它因以下错误而崩溃：

06-20 09:12:45.011: E/InputEventSender(28432): Exception dispatching finished signal.
06-20 09:12:45.011: E/MessageQueue-JNI(28432): Exception in MessageQueue callback: handleReceiveCallback
06-20 09:12:45.031: E/MessageQueue-JNI(28432): java.lang.NullPointerException

Answer 1

经典的Android问题，至少对我来说是这样。据我所知，您想要实现的目标在语法上是不可能的，但还有其他方法。您至少有 2 个选项。

在代码中动态创建视图。这看起来像下面这样：

LinearLayout layout = new LinearLayout(ArmedResponseDetailsActivity.this);
TableLayout.LayoutParams layoutParams = new TableLayout.LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.MATCH_PARENT);
layout.setLayoutParams(layoutParams);
for (int i = 0; i < 10; i++) {
    View v = new View(ArmedResponseDetailsActivity.this);
    TableLayout.LayoutParams viewParams = new TableLayout.LayoutParams(8, 30);
layoutParams.rightMargin = 5;
    v.setLayoutParams(viewParams);
    v.setBackground(R.drawable.white_mic_value);
    layout.addView(v);
}

使用 ListView along with an ArrayAdapter.

更专业和首选的方法是#2。再一次，看来您可能正在使用图像。如果是这样，您可以查看 Glide.

这样的库

Answer 2

我是这样做的：

 int[] micIDS = new int[] {R.id.white1, R.id.white2, R.id.white3, R.id.white4, R.id.white5, R.id.white6, R.id.white7, R.id.white8, R.id.white9, R.id.white10, R.id.white11, R.id.white12, R.id.white13, R.id.white14, R.id.white15, R.id.white16 };
                                for(int i= 1 ; i < 17; i++){
                                    View view = rootView.findViewById(micIDS[i-1]);
                                    Log.i("","view background: " + view.getBackground().toString());
                                    if(amplitude > i*viewThreshold) {
                                        view.setBackgroundResource(R.drawable.white_mic_value);
                                    }else{
                                        view.setBackgroundResource(R.drawable.half_white_mic_value);
                                    }
                                }

我需要从 for 中实例化和修改视图。是否可以基于 i 获取其中的 ID？

I need to instantiate and modify views from a for. Is it possible to get the ids in that for base on the i?

android

for-loop

views

findviewbyid

programmatically