質問編集履歴

viewModelを使った方法に変更

2021/12/13 13:36

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luckyclock

スコア74

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@@ -5,70 +5,294 @@
 と戻ってくるとタブ3に移動するとタブ1のフラグメントのインスタンスが消える関係で
 タブ1フラグメントでもってるmChartのインスタンスも消えてしまい、
 描画データがなくなってしまいます。
-なんとか描画データを継続して表示したいのですがどうすればよいでしょうか？
+viewModelを使って書いてみましたが、タブ1→3→1で再描画されません。
-なんとなくonSaveInstanceState使ってmchartを保持してoncreateで復元すればできるような気もす
-るのですが・・・
-あるいはタブ移動したときにフラグメントのインスタンスが破棄されないようにするとか？
 MainActivity.java
 ```java
+public class MainActivity extends AppCompatActivity {
+    private ActivityMainBinding binding;
+    private SectionsPagerAdapter sectionsPagerAdapter;
     @Override
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
-        setContentView(R.layout.activity_main);
-        mPager = (ViewPager) findViewById(R.id.pager);
-        pagerAdapter = new MyPagerAdapter(getSupportFragmentManager());
+        binding = ActivityMainBinding.inflate(getLayoutInflater());
-        mPager.setAdapter(pagerAdapter);
+        setContentView(binding.getRoot());
+        sectionsPagerAdapter = new SectionsPagerAdapter(this, getSupportFragmentManager());
-        // タブの設定
+        ViewPager viewPager = binding.viewPager;
+        viewPager.setAdapter(sectionsPagerAdapter);
-        TabLayout tabLayout = findViewById(R.id.tab_layout);
+        TabLayout tabs = binding.tabs;
-        tabLayout.setupWithViewPager(mPager);
+        tabs.setupWithViewPager(viewPager);
+        FloatingActionButton fab = binding.fab;
+        fab.setOnClickListener(new View.OnClickListener() {
+            @Override
+            public void onClick(View view) {
+                Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
+                        .setAction("Action", null).show();
+            }
+        });
+        feedMultiple();
     }
+    private Thread thread;
+    private void feedMultiple() {
+        if (thread != null)
+            thread.interrupt();
+        final Runnable runnable = new Runnable() {
+            @Override
+            public void run() {
+                if( sectionsPagerAdapter.getCurrentFragment() instanceof GraphFragment) {
+                    ((GraphFragment) sectionsPagerAdapter.getCurrentFragment()).setChart();
+                }
+            }
+        };
+        thread = new Thread(new Runnable() {
+            @Override
+            public void run() {
+                for (int i = 0; i < 1000; i++) {
+                    // Don't generate garbage runnables inside the loop.
+                    runOnUiThread(runnable);
+                    try {
+                        Thread.sleep(1000);
+                    } catch (InterruptedException e) {
+                        e.printStackTrace();
+                    }
+                }
+            }
+        });
+        thread.start();
+    }
+}
 ```
 GraphFragment.java
 ```java
+/**
+ * A placeholder fragment containing a simple view.
+ */
 public class GraphFragment extends Fragment {
-    private View rootView;
+    private PageViewModel pageViewModel;
+    private GraphFragmentBinding binding;
-    private LineChart mChart;
+    private LineChart chart;
+    private MainActivity activity;
+    public static GraphFragment newInstance() {
+        GraphFragment fragment = new GraphFragment();
+        Bundle bundle = new Bundle();
+//        bundle.putInt(ARG_SECTION_NUMBER, index);
+        fragment.setArguments(bundle);
+        return fragment;
+    }
     @Override
     public void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
+        activity = (MainActivity) getActivity();
+        pageViewModel = new ViewModelProvider(activity).get(PageViewModel.class);
+        // Create the observer which updates the UI.
+        final Observer<LineChart> observer = new Observer<LineChart>() {
+            @Override
+            public void onChanged(@Nullable final LineChart newName) {
+                // Update the UI, in this case, a TextView.
+                addEntry();
+            }
+        };
+        // Observe the LiveData, passing in this activity as the LifecycleOwner and the observer.
+        pageViewModel.getLineChart().observe(this, observer);
     }
     @Override
-    public View onCreateView(@NonNull LayoutInflater inflater,
+    public View onCreateView(
-                             ViewGroup container,
+            @NonNull LayoutInflater inflater, ViewGroup container,
-                             Bundle savedInstanceState) {
+            Bundle savedInstanceState) {
-        rootView = inflater.inflate(R.layout.fragment_graph, container, false);
+        binding = GraphFragmentBinding.inflate(inflater,container,false);;
+        View root = binding.getRoot();
+        if(pageViewModel.getValue() == null){
+            chart = binding.chart1;
+            initChart();
+        }
+        else{
-        mChart = rootView.findViewById(R.id.line_chart);
+            chart = pageViewModel.getValue();
+        }
-        return rootView;
+        return root;
     }
     @Override
-    public void onActivityCreated (Bundle savedInstanceState) {
+    public void onDestroyView() {
-        super.onActivityCreated(savedInstanceState);
+        super.onDestroyView();
+        binding = null;
     }
-    public void setData() {
+    public void setChart(){
-    	//mchartにデータセット　略
+        pageViewModel.setChart(chart);
     }
-	@Override
+    public void initChart(){
+        // enable description text
-	public void onSaveInstanceState(@NonNull Bundle outState) {
+        chart.getDescription().setEnabled(true);
+        // enable touch gestures
+        chart.setTouchEnabled(true);
+        // enable scaling and dragging
+        chart.setDragEnabled(true);
-	    super.onSaveInstanceState(outState);
+        chart.setScaleEnabled(true);
+        chart.setDrawGridBackground(false);
+        // if disabled, scaling can be done on x- and y-axis separately
+        chart.setPinchZoom(true);
+        // set an alternative background color
+        chart.setBackgroundColor(Color.LTGRAY);
+        LineData data = new LineData();
+        data.setValueTextColor(Color.WHITE);
-		// mchartを一時退避する？
+        // add empty data
+        chart.setData(data);
+        XAxis xl = chart.getXAxis();
+        xl.setLabelRotationAngle(45);
+        xl.setTextColor(Color.WHITE);
+        xl.setDrawGridLines(false);
+        xl.setAvoidFirstLastClipping(true);
+        xl.setEnabled(true);
+        YAxis leftAxis = chart.getAxisLeft();
+        leftAxis.setTextColor(Color.WHITE);
+        leftAxis.setAxisMaximum(100f);
+        leftAxis.setAxisMinimum(0f);
+        leftAxis.setDrawGridLines(true);
+        YAxis rightAxis = chart.getAxisRight();
+        rightAxis.setEnabled(false);
-	}
+    }
+    public void addEntry() {
+        LineData data = chart.getData();
+        if (data != null) {
+            ILineDataSet set = data.getDataSetByIndex(0);
+            // set.addEntry(...); // can be called as well
+            if (set == null) {
+                set = createSet();
+                data.addDataSet(set);
+            }
+            data.addEntry(new Entry(set.getEntryCount(), (float) (Math.random() * 40) + 30f), 0);
+            data.notifyDataChanged();
+            // let the chart know it's data has changed
+            chart.notifyDataSetChanged();
+            // limit the number of visible entries
+            chart.setVisibleXRangeMaximum(120);
+            // chart.setVisibleYRange(30, AxisDependency.LEFT);
+            // move to the latest entry
+            chart.moveViewToX(data.getEntryCount());
+            // this automatically refreshes the chart (calls invalidate())
+            // chart.moveViewTo(data.getXValCount()-7, 55f,
+            // AxisDependency.LEFT);
+        }
+    }
+    private LineDataSet createSet() {
+        LineDataSet set = new LineDataSet(null, "Dynamic Data");
+        set.setAxisDependency(AxisDependency.LEFT);
+        set.setColor(ColorTemplate.getHoloBlue());
+        set.setCircleColor(Color.WHITE);
+        set.setLineWidth(2f);
+        set.setCircleRadius(4f);
+        set.setFillAlpha(65);
+        set.setFillColor(ColorTemplate.getHoloBlue());
+        set.setHighLightColor(Color.rgb(244, 117, 117));
+        set.setValueTextColor(Color.WHITE);
+        set.setValueTextSize(9f);
+        set.setDrawValues(false);
+        return set;
+    }
 }
 ```
+pageViewModel.java
+```java
+package com.example.myapplication.ui.main;
+import androidx.arch.core.util.Function;
+import androidx.lifecycle.LiveData;
+import androidx.lifecycle.MutableLiveData;
+import androidx.lifecycle.Transformations;
+import androidx.lifecycle.ViewModel;
+import com.github.mikephil.charting.charts.LineChart;
+import com.github.mikephil.charting.data.LineData;
+public class PageViewModel extends ViewModel {
+    private MutableLiveData<Integer> mIndex = new MutableLiveData<>();
+    private MutableLiveData<LineChart> myLineChart = new MutableLiveData<>();
+    private LiveData<String> mText = Transformations.map(mIndex, new Function<Integer, String>() {
+        @Override
+        public String apply(Integer input) {
+            return "Hello world from section: " + input;
+        }
+    });
+    public void setIndex(int index) {
+        mIndex.setValue(index);
+    }
+    public LiveData<String> getText() {
+        return mText;
+    }
+    public void setChart(LineChart m){
+        myLineChart.setValue(m);
+    }
+    public LiveData<LineChart> getLineChart() {
+        if (myLineChart == null) {
+            myLineChart = new MutableLiveData<LineChart>();
+        }
+        return myLineChart;
+    }
+    public LineChart getValue(){
+        return myLineChart.getValue();
+    }
+}
+```
 fragment_graph.xml
 ```xml
 <?xml version="1.0" encoding="utf-8"?>