From 7e992ec284cc7b138ac9d2929de17173b3b43dc7 Mon Sep 17 00:00:00 2001
From: Nathan Harold <nharold@google.com>
Date: Tue, 12 Feb 2019 13:25:47 -0800
Subject: [PATCH] Add Class-Filtered getCellSignalStrengths

Add a version of getCellSignalStrengths that allows
the caller to pass in a particular class version of
interest, which returns only valid matching signal
strengths of that type. A caller may now do:

for(CellSignalStrengthLte lte : ss.getCellSignalStrengths(
        CellSignalStrengthLte.class)) {
    return lte.getRssnr();
}

Bug: 123939399
Test: (cts) atest SignalStrengthTest
Change-Id: Ia64d25df4e782f76e6474b92ca7cd60c2f7d2f5e
---
 api/current.txt                               |  1 +
 .../android/telephony/SignalStrength.java     | 53 ++++++++++++++++---
 2 files changed, 47 insertions(+), 7 deletions(-)

diff --git a/api/current.txt b/api/current.txt
index 95350955f163b..d311e41f3e124 100755
--- a/api/current.txt
+++ b/api/current.txt
@@ -42760,6 +42760,7 @@ package android.telephony {
     method @Deprecated public int getCdmaDbm();
     method @Deprecated public int getCdmaEcio();
     method @NonNull public java.util.List<android.telephony.CellSignalStrength> getCellSignalStrengths();
+    method public <T extends android.telephony.CellSignalStrength> java.util.List<T> getCellSignalStrengths(@NonNull Class<T>);
     method @Deprecated public int getEvdoDbm();
     method @Deprecated public int getEvdoEcio();
     method @Deprecated public int getEvdoSnr();
diff --git a/telephony/java/android/telephony/SignalStrength.java b/telephony/java/android/telephony/SignalStrength.java
index d2ae106b55456..d461bd0fee8a2 100644
--- a/telephony/java/android/telephony/SignalStrength.java
+++ b/telephony/java/android/telephony/SignalStrength.java
@@ -215,13 +215,52 @@ public class SignalStrength implements Parcelable {
      * @see android.telephony#CellSignalStrengthGsm
      */
     public @NonNull List<CellSignalStrength> getCellSignalStrengths() {
-        List<CellSignalStrength> cssList = new ArrayList<>(2); // Usually have 2 or fewer elems
-        if (mLte.isValid()) cssList.add(mLte);
-        if (mCdma.isValid()) cssList.add(mCdma);
-        if (mTdscdma.isValid()) cssList.add(mTdscdma);
-        if (mWcdma.isValid()) cssList.add(mWcdma);
-        if (mGsm.isValid()) cssList.add(mGsm);
-        if (mNr.isValid()) cssList.add(mNr);
+        return getCellSignalStrengths(CellSignalStrength.class);
+    }
+
+    /**
+     * Returns a List of CellSignalStrength Components of this SignalStrength Report.
+     *
+     * Use this API to access underlying
+     * {@link android.telephony#CellSignalStrength CellSignalStrength} objects that provide more
+     * granular information about the SignalStrength report. Only valid (non-empty)
+     * CellSignalStrengths will be returned. The order of any returned elements is not guaranteed,
+     * and the list may contain more than one instance of a CellSignalStrength type.
+     *
+     * @param clazz a class type that extends
+     *        {@link android.telephony.CellSignalStrength CellSignalStrength} to filter possible
+     *        return values.
+     * @return a List of CellSignalStrength or an empty List if there are no valid measurements.
+     *
+     * @see android.telephony#CellSignalStrength
+     * @see android.telephony#CellSignalStrengthNr
+     * @see android.telephony#CellSignalStrengthLte
+     * @see android.telephony#CellSignalStrengthTdscdma
+     * @see android.telephony#CellSignalStrengthWcdma
+     * @see android.telephony#CellSignalStrengthCdma
+     * @see android.telephony#CellSignalStrengthGsm
+     */
+    public <T extends CellSignalStrength> @NonNull List<T> getCellSignalStrengths(
+            @NonNull Class<T> clazz) {
+        List<T> cssList = new ArrayList<>(2); // Usually have 2 or fewer elems
+        if (mLte.isValid() && clazz.isAssignableFrom(CellSignalStrengthLte.class)) {
+            cssList.add((T) mLte);
+        }
+        if (mCdma.isValid() && clazz.isAssignableFrom(CellSignalStrengthCdma.class)) {
+            cssList.add((T) mCdma);
+        }
+        if (mTdscdma.isValid() && clazz.isAssignableFrom(CellSignalStrengthTdscdma.class)) {
+            cssList.add((T) mTdscdma);
+        }
+        if (mWcdma.isValid() && clazz.isAssignableFrom(CellSignalStrengthWcdma.class)) {
+            cssList.add((T) mWcdma);
+        }
+        if (mGsm.isValid() && clazz.isAssignableFrom(CellSignalStrengthGsm.class)) {
+            cssList.add((T) mGsm);
+        }
+        if (mNr.isValid() && clazz.isAssignableFrom(CellSignalStrengthNr.class)) {
+            cssList.add((T) mNr);
+        }
         return cssList;
     }