Java 在android中从filedialog获取图片并在imageview中显示
我想从文件选择器中拍摄一张照片,并将其显示在图像视图中。。但当我运行我的应用程序时,它会停止运行。问题在哪里? 这些代码是“MainActivity.java”的代码。我没有在我的项目的其他文件中更改任何内容。我的代码基于。我的代码是:Java 在android中从filedialog获取图片并在imageview中显示,java,android,Java,Android,我想从文件选择器中拍摄一张照片,并将其显示在图像视图中。。但当我运行我的应用程序时,它会停止运行。问题在哪里? 这些代码是“MainActivity.java”的代码。我没有在我的项目的其他文件中更改任何内容。我的代码基于。我的代码是: public class MainActivity extends Activity { private static final int FILE_SELECT_CODE = 0; private static final String TA
public class MainActivity extends Activity {
private static final int FILE_SELECT_CODE = 0;
private static final String TAG = null;
public TextView tv=(TextView) findViewById(R.id.textView1);
ImageView iv=(ImageView) findViewById(R.id.imageView1);
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Button b=(Button) findViewById(R.id.button1);
b.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
showFileChooser();
}
});
}
private void showFileChooser() {
Intent intent = new Intent(Intent.ACTION_GET_CONTENT);
intent.setType("*/*");
intent.addCategory(Intent.CATEGORY_OPENABLE);
try {
startActivityForResult(
Intent.createChooser(intent, "Select a File to Upload"),
FILE_SELECT_CODE);
} catch (android.content.ActivityNotFoundException ex) {
// Potentially direct the user to the Market with a Dialog
Toast.makeText(this, "Please install a File Manager.",
Toast.LENGTH_SHORT).show();
}
}
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
switch (requestCode) {
case FILE_SELECT_CODE:
if (resultCode == RESULT_OK) {
// Get the Uri of the selected file
Uri uri = data.getData();
iv.setImageURI(uri);
Log.d(TAG, "File Uri: " + uri.toString());
}
break;
}
super.onActivityResult(requestCode, resultCode, data);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
}
日志为:
12-12 04:21:32.343: D/AndroidRuntime(1068): Shutting down VM
12-12 04:21:32.343: W/dalvikvm(1068): threadid=1: thread exiting with uncaught exception (group=0xb4a60b90)
12-12 04:21:32.433: E/AndroidRuntime(1068): FATAL EXCEPTION: main
12-12 04:21:32.433: E/AndroidRuntime(1068): Process: com.example.a55j, PID: 1068
12-12 04:21:32.433: E/AndroidRuntime(1068): java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.example.a55j/com.example.a55j.MainActivity}: java.lang.NullPointerException
12-12 04:21:32.433: E/AndroidRuntime(1068): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2102)
12-12 04:21:32.433: E/AndroidRuntime(1068): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2226)
12-12 04:21:32.433: E/AndroidRuntime(1068): at android.app.ActivityThread.access$700(ActivityThread.java:135)
12-12 04:21:32.433: E/AndroidRuntime(1068): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1397)
12-12 04:21:32.433: E/AndroidRuntime(1068): at android.os.Handler.dispatchMessage(Handler.java:102)
12-12 04:21:32.433: E/AndroidRuntime(1068): at android.os.Looper.loop(Looper.java:137)
12-12 04:21:32.433: E/AndroidRuntime(1068): at android.app.ActivityThread.main(ActivityThread.java:4998)
12-12 04:21:32.433: E/AndroidRuntime(1068): at java.lang.reflect.Method.invokeNative(Native Method)
12-12 04:21:32.433: E/AndroidRuntime(1068): at java.lang.reflect.Method.invoke(Method.java:515)
12-12 04:21:32.433: E/AndroidRuntime(1068): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:777)
12-12 04:21:32.433: E/AndroidRuntime(1068): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:593)
12-12 04:21:32.433: E/AndroidRuntime(1068): at dalvik.system.NativeStart.main(Native Method)
12-12 04:21:32.433: E/AndroidRuntime(1068): Caused by: java.lang.NullPointerException
12-12 04:21:32.433: E/AndroidRuntime(1068): at android.app.Activity.findViewById(Activity.java:1883)
12-12 04:21:32.433: E/AndroidRuntime(1068): at com.example.a55j.MainActivity.<init>(MainActivity.java:23)
12-12 04:21:32.433: E/AndroidRuntime(1068): at java.lang.Class.newInstanceImpl(Native Method)
12-12 04:21:32.433: E/AndroidRuntime(1068): at java.lang.Class.newInstance(Class.java:1208)
12-12 04:21:32.433: E/AndroidRuntime(1068): at android.app.Instrumentation.newActivity(Instrumentation.java:1061)
12-12 04:21:32.433: E/AndroidRuntime(1068): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2093)
12-12 04:21:32.433: E/AndroidRuntime(1068): ... 11 more
12-12 04:21:34.823: I/Process(1068): Sending signal. PID: 1068 SIG: 9
12-1204:21:32.343:D/AndroidRuntime(1068):关闭虚拟机
12-12 04:21:32.343:W/dalvikvm(1068):threadid=1:线程以未捕获异常退出(组=0xb4a60b90)
12-1204:21:32.433:E/AndroidRuntime(1068):致命异常:主
12-1204:21:32.433:E/AndroidRuntime(1068):进程:com.example.a55j,PID:1068
12-12 04:21:32.433:E/AndroidRuntime(1068):java.lang.RuntimeException:无法实例化活动组件信息{com.example.a55j/com.example.a55j.MainActivity}:java.lang.NullPointerException
12-12 04:21:32.433:E/AndroidRuntime(1068):在android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2102)
12-12 04:21:32.433:E/AndroidRuntime(1068):在android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2226)
12-12 04:21:32.433:E/AndroidRuntime(1068):在android.app.ActivityThread.access$700(ActivityThread.java:135)
12-12 04:21:32.433:E/AndroidRuntime(1068):在android.app.ActivityThread$H.handleMessage(ActivityThread.java:1397)
12-12 04:21:32.433:E/AndroidRuntime(1068):在android.os.Handler.dispatchMessage(Handler.java:102)上
12-1204:21:32.433:E/AndroidRuntime(1068):在android.os.Looper.loop(Looper.java:137)
12-12 04:21:32.433:E/AndroidRuntime(1068):位于android.app.ActivityThread.main(ActivityThread.java:4998)
12-12 04:21:32.433:E/AndroidRuntime(1068):位于java.lang.reflect.Method.Invokenactive(本机方法)
12-12 04:21:32.433:E/AndroidRuntime(1068):在java.lang.reflect.Method.invoke(Method.java:515)
12-12 04:21:32.433:E/AndroidRuntime(1068):在com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:777)
12-1204:21:32.433:E/AndroidRuntime(1068):在com.android.internal.os.ZygoteInit.main(ZygoteInit.java:593)
12-12 04:21:32.433:E/AndroidRuntime(1068):在dalvik.system.NativeStart.main(本机方法)
12-12 04:21:32.433:E/AndroidRuntime(1068):由以下原因引起:java.lang.NullPointerException
12-12 04:21:32.433:E/AndroidRuntime(1068):在android.app.Activity.findViewById(Activity.java:1883)上
12-12 04:21:32.433:E/AndroidRuntime(1068):位于com.example.a55j.MainActivity。(MainActivity.java:23)
12-12 04:21:32.433:E/AndroidRuntime(1068):位于java.lang.Class.newInstanceImpl(本机方法)
12-12 04:21:32.433:E/AndroidRuntime(1068):位于java.lang.Class.newInstance(Class.java:1208)
12-12 04:21:32.433:E/AndroidRuntime(1068):在android.app.Instrumentation.newActivity(Instrumentation.java:1061)
12-12 04:21:32.433:E/AndroidRuntime(1068):在android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2093)
12-1204:21:32.433:E/AndroidRuntime(1068):。。。还有11个
12-12 04:21:34.823:I/进程(1068):发送信号。PID:1068信号:9
活动的主要xml是:
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context=".MainActivity" >
<TextView
android:id="@+id/textView1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="@string/hello_world" />
<Button
android:id="@+id/button1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="@+id/textView1"
android:layout_marginLeft="16dp"
android:layout_marginTop="35dp"
android:layout_toRightOf="@+id/textView1"
android:text="@string/open" />
<ImageView
android:id="@+id/imageView1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="@+id/button1"
android:layout_marginTop="81dp"
android:layout_toLeftOf="@+id/button1"
android:src="@drawable/ic_launcher" />
</RelativeLayout>
试试这个-
public class MainActivity extends Activity {
private static final int FILE_SELECT_CODE = 0;
private static final String TAG = null;
public TextView tv;
public ImageView iv;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
tv=(TextView) findViewById(R.id.textView1);
iv=(ImageView) findViewById(R.id.imageView1);
Button b=(Button) findViewById(R.id.button1);
b.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
showFileChooser();
}
});
}
private void showFileChooser() {
Intent intent = new Intent(Intent.ACTION_GET_CONTENT);
intent.setType("*/*");
intent.addCategory(Intent.CATEGORY_OPENABLE);
try {
startActivityForResult(
Intent.createChooser(intent, "Select a File to Upload"),
FILE_SELECT_CODE);
} catch (android.content.ActivityNotFoundException ex) {
// Potentially direct the user to the Market with a Dialog
Toast.makeText(this, "Please install a File Manager.",
Toast.LENGTH_SHORT).show();
}
}
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
switch (requestCode) {
case FILE_SELECT_CODE:
if (resultCode == RESULT_OK) {
// Get the Uri of the selected file
Uri uri = data.getData();
iv.setImageURI(uri);
Log.d(TAG, "File Uri: " + uri.toString());
}
break;
}
super.onActivityResult(requestCode, resultCode, data);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
}
试试这个-
public class MainActivity extends Activity {
private static final int FILE_SELECT_CODE = 0;
private static final String TAG = null;
public TextView tv;
public ImageView iv;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
tv=(TextView) findViewById(R.id.textView1);
iv=(ImageView) findViewById(R.id.imageView1);
Button b=(Button) findViewById(R.id.button1);
b.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
showFileChooser();
}
});
}
private void showFileChooser() {
Intent intent = new Intent(Intent.ACTION_GET_CONTENT);
intent.setType("*/*");
intent.addCategory(Intent.CATEGORY_OPENABLE);
try {
startActivityForResult(
Intent.createChooser(intent, "Select a File to Upload"),
FILE_SELECT_CODE);
} catch (android.content.ActivityNotFoundException ex) {
// Potentially direct the user to the Market with a Dialog
Toast.makeText(this, "Please install a File Manager.",
Toast.LENGTH_SHORT).show();
}
}
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
switch (requestCode) {
case FILE_SELECT_CODE:
if (resultCode == RESULT_OK) {
// Get the Uri of the selected file
Uri uri = data.getData();
iv.setImageURI(uri);
Log.d(TAG, "File Uri: " + uri.toString());
}
break;
}
super.onActivityResult(requestCode, resultCode, data);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
}
在android.app.Activity.findViewById(Activity.java:1883)上查看此
,这意味着您的XML文件R.layout.Activity\u main
没有名为button1
的按钮,请检查
public TextView tv=(TextView) findViewById(R.id.textView1);
ImageView iv=(ImageView) findViewById(R.id.imageView1);
设置内容视图后,将其放入OnCreate中,您甚至在布局实际膨胀之前就试图访问它们,这就是为什么会出现此错误。请参见android.app.Activity.findViewById(Activity.java:1883)
,这意味着您的XML文件R.layout.activity\u main
没有名为button1
的按钮,请检查该按钮
public TextView tv=(TextView) findViewById(R.id.textView1);
ImageView iv=(ImageView) findViewById(R.id.imageView1);
设置内容视图后,将其放入OnCreate中,您甚至在布局实际膨胀之前就试图访问它们,这就是为什么会出现此错误。尝试此操作。它在我的机器上工作 公共类MainActivity扩展了活动{
private static final int FILE_SELECT_CODE = 0;
//私有静态最终字符串标记=null
TextView tv;
ImageView iv;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Button b=(Button) findViewById(R.id.button1);
tv=(TextView) findViewById(R.id.textView1);
iv=(ImageView) findViewById(R.id.imageView1);
b.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
showFileChooser();
}
});
}
private void showFileChooser() {
Intent intent = new Intent(Intent.ACTION_GET_CONTENT);
intent.setType("*/*");
intent.addCategory(Intent.CATEGORY_OPENABLE);
try {
startActivityForResult(
Intent.createChooser(intent, "Select a File to Upload"),
FILE_SELECT_CODE);
} catch (android.content.ActivityNotFoundException ex) {
// Potentially direct the user to the Market with a Dialog
Toast.makeText(this, "Please install a File Manager.",
Toast.LENGTH_SHORT).show();
}
}
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
switch (requestCode) {
case FILE_SELECT_CODE:
if (resultCode == RESULT_OK) {
// Get the Uri of the selected file
Uri uri = data.getData();
iv.setImageURI(uri);
// Log.d(TAG, "File Uri: " + uri.toString());
}
break;
}
super.onActivityResult(requestCode, resultCode, data);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
}试试这个。它在我的机器上工作 公共类MainActivity扩展了活动{
private static final int FILE_SELECT_CODE = 0;
//私有静态最终字符串标记=null
TextView tv;
ImageView iv;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Button b=(Button) findViewById(R.id.button1);
tv=(TextView) findViewById(R.id.textView1);
iv=(ImageView) findViewById(R.id.imageView1);
b.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
showFileChooser();
}
});
}
private void showFileChooser() {
Intent intent = new Intent(Intent.ACTION_GET_CONTENT);
intent.setType("*/*");
intent.addCategory(Intent.CATEGORY_OPENABLE);
try {
startActivityForResult(
Intent.createChooser(intent, "Select a File to Upload"),
FILE_SELECT_CODE);
} catch (android.content.ActivityNotFoundException ex) {
// Potentially direct the user to the Market with a Dialog
Toast.makeText(this, "Please install a File Manager.",
Toast.LENGTH_SHORT).show();
}
}
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
switch (requestCode) {
case FILE_SELECT_CODE:
if (resultCode == RESULT_OK) {
// Get the Uri of the selected file
Uri uri = data.getData();
iv.setImageURI(uri);
// Log.d(TAG, "File Uri: " + uri.toString());
}
break;
}
super.onActivityResult(requestCode, resultCode, data);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
}根据您的
LogCat错误
您将获得NullPointerException
初始化您的ImageView
和TextView
全局(在OnCreate
之前)像ImageView iv;
TextView tv;
并将
findViewById(R.id.imageView1)
和findViewById(R.id.textView1)
放在onCreate
方法中。根据您的LogCat错误
您将获得NullPointerException
初始化您的ImageView
和TextView
全局(在OnCreate
之前)像ImageView iv;
TextView tv;
并将
findViewById(R.id.imageView1)
和findViewById(R.id.textView1)
放在onCreate
方法中。您能发布日志吗here@sachingarg我编辑我的答案并添加登录您的主要活动哪个是23行?@KanwaljitSingh。。什么?在哪里?发布您的活动\u main.xml。您可以发布日志吗here@sachingarg我编辑我的答案并添加登录您的主要活动哪个是23行?@KanwaljitSingh。。什么?在哪里?发布你的活动_main.xml。我做了,但我的问题没有解决。当我运行它的时候,我的应用程序停止了并且没有运行。试一下Techfist所说的。检查xml中按钮的名称。OK运行正常。但是当从文件资源管理器中选择图片时,imageview没有显示任何内容。查看此链接,我这样做了,但我的问题没有解决。当我运行它的时候,我的应用程序停止了并且没有运行。试一下Techfist所说的。检查xml中按钮的名称。OK运行正常。但是当从文件资源管理器中选择图片时,imageview没有显示任何内容。查看此链接,我将按钮1
我自己放入活动\u main.xml
中并进行了检查。我在上面看到这个按钮!!!!我在回答中添加了xml文件修改了我的回答,更改您的