该应用程序是当成员单击btn相机时打开的,并拍照并在图像视图中看到它。当他关闭应用程序时,图片需要保存在内部存储器中。 问题是当我在btn中单击并在拍照后单击V时,应用程序崩溃了/
package com.e.test;
import android.content.Intent;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.provider.MediaStore;
import android.support.annotation.Nullable;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.ImageView;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
public class MainActivity extends AppCompatActivity {
全局变量:
final int CAMERA_REQUEST = 1;
ImageView imageview;
Bitmap bitmap;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
这是加载图像:
try {
FileInputStream fis = openFileInput("pictures");
bitmap = BitmapFactory.decodeStream(fis);
imageview.setImageBitmap(bitmap);
fis.close();
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
Button btn = findViewById(R.id.btn);
imageview = findViewById(R.id.image_result);
btn.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Intent intent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
startActivityForResult(intent,CAMERA_REQUEST);
}
});
}
@Override
protected void onActivityResult(int requestCode, int resultCode, @Nullable Intent data) {
super.onActivityResult(requestCode, resultCode, data);
if(requestCode == CAMERA_REQUEST && resultCode == RESULT_OK)
{
bitmap = (Bitmap)data.getExtras().get("data");
imageview.setImageBitmap(bitmap);
}
}
这是保存:
@Override
protected void onPause() {
super.onPause();
try {
FileOutputStream fos = openFileOutput("pictures",MODE_PRIVATE);
bitmap.compress(Bitmap.CompressFormat.JPEG,50,fos);
fos.close();
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
}
答案 0 :(得分:1)
发生NullPointerException
是因为您的bitmap
实例为空。不确定如何使用此代码,但是可以添加一个空检查,以确保bitmap
在执行操作(例如压缩)时不为空。这样您的应用程序将不会崩溃。像这样:
@Override
protected void onPause() {
super.onPause();
try {
if(bitmap != null){
FileOutputStream fos = openFileOutput("pictures",MODE_PRIVATE);
bitmap.compress(Bitmap.CompressFormat.JPEG,50,fos);
fos.close();
}
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}