我正在做ImageSwitcher，它正在完美地尝试将ImageSwitcher图像发送到另一个活动.. ImageSwitcher工作完美但是点击按钮进入下一个活动后，错误：Views.java中的（imageview）中的空指针异常
MainEvent.java
///<reference path="../../../../../typings/tsd.d.ts"/>
import {Component, OnInit} from 'angular2/core'
import {Router} from 'angular2/router';
import {NgClass} from 'angular2/common';
import {ImageInterface} from './image.interface'
import {ImageService} from './image.service'
import {ImageModel as Image} from './image.model'
import {ImageComponent} from './image.component'
@Component({
selector: 'create-images-component',
templateUrl: './angular2/app/images/image-form.component.html',
providers: [
ImageService
],
directives: [
ErrorsComponent,
NgClass,
] })
export class CreateImageComponent implements OnInit {
public image:ImageInterface = new Image();
public validationErrors;
constructor(public service:ImageService,
private _router:Router) {
}
/**
* File input change event
* @param event
*/
onFileChange(event) {
let file = event.target.files[0];
if (!file) {
return;
}
if ( this.isValidExtension(file) == false ) {
swal('Invalid file format!', 'Invalid file Format. Only ' + ImageComponent.ALLOWED_EXTENSIONS.join(', ') + ' are allowed.', 'error');
return false;
}
if (this.isValidFileSize(file) == false) {
swal('Invalid file size!', 'Invalid file size. Max allowed is : ' + ImageComponent.ALLOWED_SIZE + ', your file is : ' + this.getFileSize(file) + ' Mb' , 'error');
return;
}
console.log(file);
let reader = new FileReader();
reader.onload = (e) => {
this.image.base64 = e.target.result;
};
reader.readAsDataURL(file);
}
/**
* Check if file has valid extension
* @param file
*/
private isValidExtension(file:File):boolean {
let allowedExtensions = ImageComponent.ALLOWED_EXTENSIONS;
let extension = file.name.split('.').pop();
return allowedExtensions.indexOf(extension) !== -1
}
/**
* Check file size
* @param file
* @returns {boolean}
*/
private isValidFileSize(file) {
let size = this.getFileSize(file);
return size < ImageComponent.ALLOWED_SIZE;
}
/**
* GEt file size in Mb
* @param file
* @returns {Number}
*/
private getFileSize(file:File):Number {
return file.size / 1024 / 1024;
}
/**
* Clear selected image
* @param ev
*/
clearImage(ev) {
ev.preventDefault();
this.image.base64 = ''
}
/**
* Return if image exists
* @returns {boolean}
*/
fileExists() {
return this.image.base64 && (typeof this.image.base64 !== 'undefined')
}
/**
* Create new image
*/
onSubmit(form) {
return this.service.httpPost(this.image)
.subscribe(
(res) => {
if (res.data.errors) {
this.validationErrors = res.data.errors;
}
if (res.status == "success") {
this.successMessage = res.message;
swal("Good Job", res.message, "success");
this.validationErrors = [];
} else {
this.errorMessage = res.message;
}
},
(error) => this.errorMessage = <any>error);
}
onCancel() {
return this._router.navigate(['Images']);
}
get diagnostic() {
return JSON.stringify(this.image);
}
}
Views.java
import android.app.Activity;
import android.content.Intent;
import android.graphics.Bitmap;
import android.graphics.drawable.BitmapDrawable;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.view.animation.Animation;
import android.view.animation.AnimationUtils;
import android.widget.Button;
import android.widget.ImageSwitcher;
import android.widget.ImageView;
import android.widget.ViewSwitcher;
import java.io.ByteArrayOutputStream;
public class MainEvent extends Activity {
private ImageSwitcher imageSwitcher;
Button btnNext,back,select,refresh;
ImageView imageView;
// Array of Image IDs to Show In ImageSwitcher
int imageIds[]={R.drawable.frame3,R.drawable.frame7,
R.drawable.curtain,R.drawable.potraitimage
};
int messageCount=imageIds.length;
// to keep current Index of ImageID array
int currentIndex=0;
Animation in,out;
@Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main_event);
// get The references
btnNext=(Button)findViewById(R.id.button2);
back=(Button)findViewById(R.id.button);
select=(Button)findViewById(R.id.select);
refresh=(Button)findViewById(R.id.refresh);
imageSwitcher = (ImageSwitcher) findViewById(R.id.imageSwitcher);
// Set the ViewFactory of the ImageSwitcher that will create
ImageView object when asked
imageSwitcher.setFactory(new ViewSwitcher.ViewFactory() {
public View makeView() {
// TODO Auto-generated method stub
// Create a new ImageView set it's properties
imageView = new ImageView(getApplicationContext());
imageView.setScaleType(ImageView.ScaleType.FIT_CENTER);
imageView.setImageResource(R.drawable.potraitimage);
return imageView;
}
});
// Declare the animations and initialize them
in = AnimationUtils.loadAnimation(this,android.R.anim.slide_in_left);
out = AnimationUtils.loadAnimation(this, android.R.anim.slide_out_right);
// set the animation type to imageSwitcher
imageSwitcher.setInAnimation(in);
imageSwitcher.setOutAnimation(out);
// ClickListener for NEXT button
// When clicked on Button ImageSwitcher will switch between Images
// The current Image will go OUT and next Image will come
in with specified animation
btnNext.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
// TODO Auto-generated method stub
imageView.setImageResource(0);
Log.d("index", String.valueOf(currentIndex));
currentIndex++;
Log.d("index", String.valueOf(currentIndex));
// If index reaches maximum reset it
if(currentIndex==messageCount)
currentIndex=0;
imageSwitcher.setImageResource(imageIds[currentIndex]);
}
});
back.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
// set the animation type to imageSwitcher
// TODO Auto-generated method stub
Log.d("index", String.valueOf(currentIndex));
currentIndex--;
Log.d("index", String.valueOf(currentIndex));
// If index reaches maximum reset it
if (currentIndex < 0)
currentIndex = 2;
imageSwitcher.setImageResource(imageIds[currentIndex]);
}
});
select.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
imageView.setImageResource(imageIds[currentIndex]);
BitmapDrawable drawable = (BitmapDrawable) imageView.getDrawable();
Bitmap bitmap = drawable.getBitmap();
Intent in=new Intent(MainEvent.this,Camera.class);
/* in.putExtra("image",bitmap);*/
ByteArrayOutputStream stream = new ByteArrayOutputStream();
bitmap.compress(Bitmap.CompressFormat.PNG, 100, stream);
byte[] byteArray = stream.toByteArray();
Bundle bu=new Bundle();
bu.putByteArray("ImageByte",byteArray );
in.putExtras(bu);
startActivity(in);
}
});
refresh.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
onRestart();
}
});
}
@Override
protected void onRestart() {
// TODO Auto-generated method stub
super.onRestart();
Intent i = new Intent(MainEvent.this, MainEvent.class); //your class
startActivity(i);
finish();
}
}
我不知道如何将图像从imageswitcher传递到下一个活动..请帮助我们..
答案 0 :(得分：1)
而不是传入图像的字节，你不能只传入它所在的索引（int）吗？
那会更有效率。
（以下链中的扩展答案） 在两个活动中共享数组。 关于静态属性的简单方法：
public class StaticModelManager {
public static int imageIds[];
}
然后在应用程序的任何位置获取或设置它：
StaticModelManager.imageIds = {
R.drawable.frame3,
R.drawable.frame7,
R.drawable.curtain,
R.drawable.potraitimage
};
使用它们：
StaticModelManager.imageIds[currentIndex];
多个活动或片段可以轻松访问这一个实例。只需确保在不需要时将其清理干净或将其存放在内存中。