场景
Android中点击按钮启动另一个Activity以及Activity之间传值:
http://www.tuohang.net/article/253479.html
在上面启动Activity和传值之后,怎样获取Acitvity的返回值。下面示例实现点击选择头像按钮,跳转到头像显示Activity,并将选择的图片的索引返回,在MainActivity中获取后设置头像。
效果
注:
实现
首先是主页面MainActivity的布局,添加一个选择头像按钮和一个ImageView用来显示头像。
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<?xml version= "1.0" encoding= "utf-8" ?> <LinearLayout xmlns:android= "http://schemas.android.com/apk/res/android" xmlns:app= "http://schemas.android.com/apk/res-auto" xmlns:tools= "http://schemas.android.com/tools" android:layout_width= "match_parent" android:layout_height= "match_parent" android:orientation= "vertical" tools:context= ".MainActivity" > <ImageView android:id= "@+id/image" android:layout_width= "wrap_content" android:layout_height= "wrap_content" /> <Button android:id= "@+id/button" android:text= "选择头像" android:layout_width= "wrap_content" android:layout_height= "wrap_content" /> </LinearLayout> |
然后在MainActivity中的OnCreate方法中,使用startActivityForResult能启动另一个Activity并能获得返回结果。
要设置一个请求码,这里是200。
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Button button = (Button)findViewById(R.id.button); button.setOnClickListener( new View.OnClickListener() { @Override public void onClick(View v) { Intent intent = new Intent(MainActivity. this ,HeadActivity. class ); startActivityForResult(intent, 200 ); } }); |
然后跳转到第二个Activity用来选择头像。首先设置其布局文件,添加一个GridView用来显示要选择的头像照片。
activity_head.xml
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<?xml version= "1.0" encoding= "utf-8" ?> <LinearLayout xmlns:android= "http://schemas.android.com/apk/res/android" xmlns:app= "http://schemas.android.com/apk/res-auto" xmlns:tools= "http://schemas.android.com/tools" android:layout_width= "match_parent" android:layout_height= "match_parent" android:orientation= "vertical" tools:context= ".HeadActivity" > <GridView android:id= "@+id/gridView" android:numColumns= "4" android:layout_width= "wrap_content" android:layout_height= "wrap_content" /> </LinearLayout> |
然后来到其Activity,使用适配器为其设置照片源。
首先声明一个图片数组
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private int [] imageId = new int []{ R.drawable.img1,R.drawable.img2 }; |
这里引用了drawable下的两张头像照片。
然后使用适配器为照片设置数据源
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GridView gridView = (GridView) findViewById(R.id.gridView); BaseAdapter adapter = new BaseAdapter() { @Override public int getCount() { return imageId.length; } @Override public Object getItem( int position) { return null ; } @Override public long getItemId( int position) { return 0 ; } @Override public View getView( int position, View convertView, ViewGroup parent) { ImageView imageView; if (convertView == null ) { imageView = new ImageView(HeadActivity. this ); imageView.setAdjustViewBounds( true ); imageView.setMaxWidth( 158 ); imageView.setMaxHeight( 150 ); imageView.setPadding( 5 , 5 , 5 , 5 ); } else { imageView = (ImageView) convertView; } imageView.setImageResource(imageId[position]); return imageView; } }; gridView.setAdapter(adapter); |
然后在gridView的选项点击事件监听器中,获取选中照片的索引并通过Bundle对象的putInt和intent对象的putExtras将数据进行返回。然后调用 setResult(200,intent);将结果进行返回,这里的请求结果码也设置为200。
完整HeadActivity.java
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package com.badao.selectimage; import androidx.appcompat.app.AppCompatActivity; import android.content.Intent; import android.os.Bundle; import android.view.View; import android.view.ViewGroup; import android.widget.AdapterView; import android.widget.BaseAdapter; import android.widget.GridView; import android.widget.ImageView; public class HeadActivity extends AppCompatActivity { private int [] imageId = new int []{ R.drawable.img1,R.drawable.img2 }; @Override protected void onCreate(Bundle savedInstanceState) { GridView gridView = (GridView) findViewById(R.id.gridView); BaseAdapter adapter = new BaseAdapter() { @Override public int getCount() { return imageId.length; } @Override public Object getItem( int position) { return null ; } @Override public long getItemId( int position) { return 0 ; } @Override public View getView( int position, View convertView, ViewGroup parent) { ImageView imageView; if (convertView == null ) { imageView = new ImageView(HeadActivity. this ); imageView.setAdjustViewBounds( true ); imageView.setMaxWidth( 158 ); imageView.setMaxHeight( 150 ); imageView.setPadding( 5 , 5 , 5 , 5 ); } else { imageView = (ImageView) convertView; } imageView.setImageResource(imageId[position]); return imageView; } }; gridView.setAdapter(adapter); super .onCreate(savedInstanceState); setContentView(R.layout.activity_head); gridView.setOnItemClickListener( new AdapterView.OnItemClickListener() { @Override public void onItemClick(AdapterView<?> parent, View view, int position, long id) { Intent intent = getIntent(); Bundle bundle = new Bundle(); bundle.putInt( "imageId" ,imageId[position]); intent.putExtras(bundle); setResult( 200 ,intent); finish(); } }); } } |
然后回到MainActivity怎样接受返回的结果。
ctrl + O重写方法 onActivityResult,如果请求码和返回结果码都是200,首先通过
Bundle bundle = data.getExtras();
获取Bundle对象。
然后通过
int imageId = bundle.getInt("imageId");
获取返回的照片索引数据。
然后给ImageView设置照片源。
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@Override protected void onActivityResult( int requestCode, int resultCode, @Nullable Intent data) { super .onActivityResult(requestCode, resultCode, data); if (requestCode == 200 && resultCode == 200 ) { Bundle bundle = data.getExtras(); int imageId = bundle.getInt( "imageId" ); ImageView imageView = (ImageView) findViewById(R.id.image); imageView.setImageResource(imageId); } } |
MainActivity完整示例代码
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package com.badao.selectimage; import androidx.annotation.Nullable; import androidx.appcompat.app.AppCompatActivity; import android.content.Intent; import android.os.Bundle; import android.view.View; import android.widget.Button; import android.widget.ImageView; public class MainActivity extends AppCompatActivity { @Override protected void onActivityResult( int requestCode, int resultCode, @Nullable Intent data) { super .onActivityResult(requestCode, resultCode, data); if (requestCode == 200 && resultCode == 200 ) { Bundle bundle = data.getExtras(); int imageId = bundle.getInt( "imageId" ); ImageView imageView = (ImageView) findViewById(R.id.image); imageView.setImageResource(imageId); } } @Override protected void onCreate(Bundle savedInstanceState) { super .onCreate(savedInstanceState); setContentView(R.layout.activity_main); Button button = (Button)findViewById(R.id.button); button.setOnClickListener( new View.OnClickListener() { @Override public void onClick(View v) { Intent intent = new Intent(MainActivity. this ,HeadActivity. class ); startActivityForResult(intent, 200 ); } }); } } |
总结
以上所述是小编给大家介绍的Android中调用另一个Activity并返回结果(选择头像功能为例),希望对大家有所帮助,如果大家有任何疑问请给我留言,小编会及时回复大家的。在此也非常感谢大家对服务器之家网站的支持!
如果你觉得本文对你有帮助,欢迎转载,烦请注明出处,谢谢!
原文链接:https://www.cnblogs.com/badaoliumangqizhi/archive/2020/01/10/12175548.html