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私はUserListアクティビティからPieChartActivityを呼び出しています。 PieChartActivityはうまく表示されますが、前のアクティビティ（UserListアクティビティ）が表示されてからアプリがクラッシュします。いずれかのPieChartActivityで背中が押されたときのヌルポインタ例外MPAndroidChartを使用
12-22 12:33:51.996 76-98/? I/ActivityManager: Displayed com.example.naseera.userlogin/.PieChartActivity: +10s654ms
12-22 12:33:56.581 745-745/? D/AndroidRuntime: Shutting down VM
12-22 12:33:56.581 745-745/? W/dalvikvm: threadid=1: thread exiting with uncaught exception (group=0x40014760)
12-22 12:33:56.841 745-745/? E/AndroidRuntime: FATAL EXCEPTION: main
12-22 12:33:56.841 745-745/? E/AndroidRuntime: java.lang.NullPointerException
12-22 12:33:56.841 745-745/? E/AndroidRuntime: at android.graphics.Canvas.setBitmap(Canvas.java:177)
12-22 12:33:56.841 745-745/? E/AndroidRuntime: at com.github.mikephil.charting.renderer.PieChartRenderer.releaseBitmap(PieChartRenderer.java:985)
12-22 12:33:56.841 745-745/? E/AndroidRuntime: at com.github.mikephil.charting.charts.PieChart.onDetachedFromWindow(PieChart.java:726)
12-22 12:33:56.841 745-745/? E/AndroidRuntime: at android.view.View.dispatchDetachedFromWindow(View.java:8197)
12-22 12:33:56.841 745-745/? E/AndroidRuntime: at android.view.ViewGroup.dispatchDetachedFromWindow(ViewGroup.java:1968)
12-22 12:33:56.841 745-745/? E/AndroidRuntime: at android.view.ViewGroup.dispatchDetachedFromWindow(ViewGroup.java:1966)
12-22 12:33:56.841 745-745/? E/AndroidRuntime: at android.view.ViewGroup.dispatchDetachedFromWindow(ViewGroup.java:1966)
12-22 12:33:56.841 745-745/? E/AndroidRuntime: at android.view.ViewGroup.dispatchDetachedFromWindow(ViewGroup.java:1966)
12-22 12:33:56.841 745-745/? E/AndroidRuntime: at android.view.ViewGroup.dispatchDetachedFromWindow(ViewGroup.java:1966)
12-22 12:33:56.841 745-745/? E/AndroidRuntime: at android.view.ViewGroup.dispatchDetachedFromWindow(ViewGroup.java:1966)
12-22 12:33:56.841 745-745/? E/AndroidRuntime: at android.view.ViewGroup.dispatchDetachedFromWindow(ViewGroup.java:1966)
12-22 12:33:56.841 745-745/? E/AndroidRuntime: at android.view.ViewGroup.dispatchDetachedFromWindow(ViewGroup.java:1966)
12-22 12:33:56.841 745-745/? E/AndroidRuntime: at android.view.ViewRoot.dispatchDetachedFromWindow(ViewRoot.java:1887)
12-22 12:33:56.841 745-745/? E/AndroidRuntime: at android.view.ViewRoot.doDie(ViewRoot.java:3191)
12-22 12:33:56.841 745-745/? E/AndroidRuntime: at android.view.ViewRoot.die(ViewRoot.java:3159)
12-22 12:33:56.841 745-745/? E/AndroidRuntime: at android.view.WindowManagerImpl.removeViewImmediate(WindowManagerImpl.java:222)
12-22 12:33:56.841 745-745/? E/AndroidRuntime: at android.view.Window$LocalWindowManager.removeViewImmediate(Window.java:538)
12-22 12:33:56.841 745-745/? E/AndroidRuntime: at android.app.ActivityThread.handleDestroyActivity(ActivityThread.java:2912)
12-22 12:33:56.841 745-745/? E/AndroidRuntime: at android.app.ActivityThread.access$2100(ActivityThread.java:122)
12-22 12:33:56.841 745-745/? E/AndroidRuntime: at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1035)
12-22 12:33:56.841 745-745/? E/AndroidRuntime: at android.os.Handler.dispatchMessage(Handler.java:99)
12-22 12:33:56.841 745-745/? E/AndroidRuntime: at android.os.Looper.loop(Looper.java:132)
12-22 12:33:56.841 745-745/? E/AndroidRuntime: at android.app.ActivityThread.main(ActivityThread.java:4025)
12-22 12:33:56.841 745-745/? E/AndroidRuntime: at java.lang.reflect.Method.invokeNative(Native Method)
12-22 12:33:56.841 745-745/? E/AndroidRuntime: at java.lang.reflect.Method.invoke(Method.java:491)
12-22 12:33:56.841 745-745/? E/AndroidRuntime: at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:841)
12-22 12:33:56.841 745-745/? E/AndroidRuntime: at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:599)
12-22 12:33:56.841 745-745/? E/AndroidRuntime: at dalvik.system.NativeStart.main(Native Method)
12-22 12:33:56.881 76-76/? W/ActivityManager: Force finishing activity com.example.naseera.userlogin/.Userlist
12-22 12:33:57.661 76-85/? W/ActivityManager: Activity pause timeout for ActivityRecord{40922448 com.example.naseera.userlogin/.Userlist}
12-22 12:34:01.601 745-745/? I/Process: Sending signal. PID: 745 SIG: 9
前のアクティビティが表示されます。これは、logcatがある
package com.example.naseera.userlogin;
import android.content.Context;
import android.content.Intent;
import android.content.res.Resources;
import android.graphics.Color;
import android.os.Handler;
import android.support.v4.content.ContextCompat;
import android.support.v4.content.res.ResourcesCompat;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.support.v7.widget.Toolbar;
import android.util.Log;
import android.util.TypedValue;
import android.view.Menu;
import android.view.MenuItem;
import android.view.WindowManager;
import android.widget.Toast;
import com.github.mikephil.charting.animation.Easing;
import com.github.mikephil.charting.charts.PieChart;
import com.github.mikephil.charting.components.Legend;
import com.github.mikephil.charting.data.Entry;
import com.github.mikephil.charting.data.PieData;
import com.github.mikephil.charting.data.PieDataSet;
import com.github.mikephil.charting.data.PieEntry;
import com.github.mikephil.charting.highlight.Highlight;
import com.github.mikephil.charting.listener.OnChartValueSelectedListener;
import java.util.ArrayList;
public class PieChartActivity extends AppCompatActivity{
private float[] yData;
//private float[] yData2 = {25.0f, 10.0f,66.0f};
private String[] xData = {"Admin", "Standard User","Premium User"};
PieChart pieChart;
private DBHelper db;
public Toolbar tb;
private static String TAG = ".PieChartActivity";
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_piechart);
tb = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(tb);
if (getSupportActionBar() != null){
getSupportActionBar().setDisplayHomeAsUpEnabled(true);
getSupportActionBar().setDisplayShowHomeEnabled(true);
}
TypedValue typedValue = new TypedValue();
getTheme().resolveAttribute(R.attr.colorPrimaryDark, typedValue, true);
int color = typedValue.data;
pieChart = (PieChart) findViewById(R.id.idPieChart);
// pieChart.setDescription("User Types");
pieChart.setRotationEnabled(true);
pieChart.setHoleRadius(30f);
pieChart.setTransparentCircleRadius(35f);
pieChart.setTransparentCircleAlpha(0);
pieChart.setCenterText("Registered Users");
pieChart.setCenterTextSize(20);
pieChart.setCenterTextColor(color);
pieChart.setDrawEntryLabels(true);
pieChart.setEntryLabelTextSize(20);
pieChart.setTransparentCircleRadius(61f);
pieChart.setNoDataTextColor(Color.RED);
addDataSet();
pieChart.setOnChartValueSelectedListener(new OnChartValueSelectedListener() {
@Override
public void onValueSelected(Entry e, Highlight h) {
if (e == null)
return;
Log.i("VAL SELECTED",
"Value: " + e.getY() + ", index: " + h.getX()
+ ", DataSet index: " + h.getDataSetIndex());
String usertype = xData[Math.round(h.getX())];
System.out.println(usertype);
int numberofusers = Math.round(e.getY());
System.out.println(numberofusers);
Toast.makeText(PieChartActivity.this, usertype +" = " + numberofusers, Toast.LENGTH_SHORT).show();
; }
@Override
public void onNothingSelected() {
}
});
}
private void addDataSet() {
db = new DBHelper(this);
yData = db.getNumberOfUsers();
ArrayList<PieEntry> entries = new ArrayList<>();
entries.add(new PieEntry(Math.round(yData[0]),"Admin"));
entries.add(new PieEntry(Math.round(yData[1]),"Standard User"));
entries.add(new PieEntry(Math.round(yData[2]), "Premium User"));
TypedValue typedValue = new TypedValue();
getTheme().resolveAttribute(R.color.green, typedValue, true);
int greencolor = typedValue.data;
PieDataSet pieDataSet = new PieDataSet(entries, "Registered Users");
pieDataSet.setSliceSpace(2);
pieDataSet.setValueTextSize(20);
pieDataSet.setColor(Color.WHITE);
pieDataSet.setValueTextColor(Color.WHITE);
//add colors to dataset
ArrayList<Integer> colors = new ArrayList<>();
colors.add(ContextCompat.getColor(this, R.color.deeporange));
colors.add(ContextCompat.getColor(this, R.color.teal));
colors.add(ContextCompat.getColor(this, R.color.purple));
pieDataSet.setColors(colors);
//add legend to chart
Legend legend = pieChart.getLegend();
legend.setForm(Legend.LegendForm.CIRCLE);
legend.setFormSize(15);
legend.setTextSize(15);
//legend.setPosition(Legend.LegendPosition.BELOW_CHART_LEFT);
Legend l = pieChart.getLegend();
l.setVerticalAlignment(Legend.LegendVerticalAlignment.TOP);
l.setHorizontalAlignment(Legend.LegendHorizontalAlignment.RIGHT);
l.setOrientation(Legend.LegendOrientation.VERTICAL);
l.setDrawInside(false);
l.setXEntrySpace(7f);
l.setYEntrySpace(0f);
l.setYOffset(0f);
//create pie data object
PieData pieData = new PieData(pieDataSet);
pieChart.setData(pieData);
pieChart.invalidate();
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
switch (item.getItemId()) {
case android.R.id.home:
onBackPressed();
return true;
default:
return super.onOptionsItemSelected(item);
}
}
@Override
public void onBackPressed(){
super.onBackPressed();
}
}
}
：これは私のPieChartActivityある
@Override
public boolean onOptionsItemSelected(MenuItem item) {
switch (item.getItemId()) {
case android.R.id.home:
onBackPressed();
return true;
case R.id.action_piechart:
Intent intentPiechart = new Intent(Userlist.this, PieChartActivity.class);
startActivity(intentPiechart);
return true;
case R.id.action_logout:
session.setLoggedin(false);
Intent intentMain = new Intent(Userlist.this, MainActivity.class);
startActivity(intentMain);
finish();
return true;
// action with ID action_settings was selected
default:
return super.onOptionsItemSelected(item);
}
：私はPiceChartActivityに意図を呼び出すのはここ
です次にアプリがクラッシュします。どんな助けも素晴らしいでしょう。ありがとう。
以下は、logcatに表示されるコード領域です。
Canvas.java
public void setBitmap(@Nullable Bitmap bitmap) {
if (isHardwareAccelerated()) {
throw new RuntimeException("Can't set a bitmap device on a HW accelerated canvas");
}
if (bitmap == null) {
native_setBitmap(mNativeCanvasWrapper, null);
mDensity = Bitmap.DENSITY_NONE;
} else {
if (!bitmap.isMutable()) {
throw new IllegalStateException();
}
throwIfCannotDraw(bitmap);
native_setBitmap(mNativeCanvasWrapper, bitmap);
mDensity = bitmap.mDensity;
}
mBitmap = bitmap;
}
PieChartRenderer.java
public void releaseBitmap() {
if (mBitmapCanvas != null) {
mBitmapCanvas.setBitmap(null); /*points to this line*/
mBitmapCanvas = null;
}
if (mDrawBitmap != null) {
mDrawBitmap.get().recycle();
mDrawBitmap.clear();
mDrawBitmap = null;
}
}
PieChart.java
@Override
protected void onDetachedFromWindow() {
// releases the bitmap in the renderer to avoid oom error
if (mRenderer != null && mRenderer instanceof PieChartRenderer) {
((PieChartRenderer) mRenderer).releaseBitmap();
}
super.onDetachedFromWindow();
}
あなたはなぜandroid.graphics.Canvas.setBitmap（Canvas.java:177）がnullになるのかチェックしてください。 –
onBackPressedを上書きしないでください。それは奇妙に見える。 –
私はonBackPressedメソッドを編集し、新しいlogcatも投稿しました。 –