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Android Activity间传送自定义类的对象

热度:50   发布时间:2016-05-01 15:52:07.0
Android Activity间传递自定义类的对象
有很多时候都需要在不同的Activity之间传递数据。
实现方法有很多,可以用Bundle来传递,也可以用给Intent用putExtra传递附加参数。
当然也可以传递自定义类的对象。为了让自定义类可以在Activity之间传递,必须符合一些条件。常用的方法是自定义类实现Parcelable接口或Serializable接口。Android中建议实现Parcelable。
下面例子中两种方法都有例子。
传递Parcelable过去,再传递Serializable回来。





WeightParcelable.java
import android.os.Parcel;import android.os.Parcelable;public class WeightParcelable implements Parcelable {	private String sex;	private double height;//必须的空构造器,因为下面有一个私有的构造器,否则不能new对象	public WeightParcelable() {	}	public String getSex() {		return sex;	}	public void setSex(String sex) {		this.sex = sex;	}	public double getHeight() {		return height;	}	public void setHeight(double height) {		this.height = height;	}	@Override	public int describeContents() {		return 0;	}//需要覆盖的方法	@Override	public void writeToParcel(Parcel out, int flags) {		out.writeString(sex);		out.writeDouble(height);	}//关键的事情	public static final Parcelable.Creator<WeightParcelable> CREATOR = new Parcelable.Creator<WeightParcelable>() {		public WeightParcelable createFromParcel(Parcel in) {			return new WeightParcelable(in);		}		public WeightParcelable[] newArray(int size) {			return new WeightParcelable[size];		}	};//	private WeightParcelable(Parcel in) {		sex = in.readString();		height = in.readDouble();	}}


HeightSerializable.java
import java.io.Serializable;public class HeightSerializable implements Serializable {	private static final long serialVersionUID = 8502706820090766507L;	private String sex;	private double weight;	public String getSex() {		return sex;	}	public void setSex(String sex) {		this.sex = sex;	}	public double getWeight() {		return weight;	}	public void setWeight(double weight) {		this.weight = weight;	}}


EX03_10.java
import android.app.Activity;import android.content.Intent;import android.os.Bundle;import android.util.Log;import android.view.View;import android.widget.Button;import android.widget.EditText;import android.widget.RadioButton;import android.widget.TextView;public class EX03_10 extends Activity {	/** Called when the activity is first created. */	public static final String parcelableKey = "irdc.ex03_10.parcelableKey";	public static final String seralizableKey = "irdc.ex03_10.seralizableKey";	private static final String TAG = "EX03_10";	@Override	public void onCreate(Bundle savedInstanceState) {		super.onCreate(savedInstanceState);		setContentView(R.layout.main);		Button b1 = (Button) findViewById(R.id.button1);		b1.setOnClickListener(new Button.OnClickListener() {			public void onClick(View v) {				EditText et = (EditText) findViewById(R.id.height);				double height = Double.parseDouble(et.getText().toString());				String sex = "";				RadioButton rb1 = (RadioButton) findViewById(R.id.sex1);				if (rb1.isChecked()) {					sex = "M";				} else {					sex = "F";				}				Intent intent = new Intent();				intent.setClass(EX03_10.this, EX03_10_1.class);				Bundle bundle = new Bundle();				WeightParcelable wp = new WeightParcelable();				wp.setSex(sex);				wp.setHeight((int) height);				bundle.putParcelable(parcelableKey, wp);				intent.putExtras(bundle);//注意这里				startActivityForResult(intent, 1);			}		});	}//这个是关键	@Override	protected void onActivityResult(int requestCode, int resultCode, Intent data) {		Log.d(TAG, "onActivityResult requestCode=" + requestCode				+ " resultCode= " + resultCode + " data == null["				+ (data == null) + "]");		super.onActivityResult(requestCode, resultCode, data);		if (requestCode == 1) {			if (resultCode == RESULT_OK) {				try {					HeightSerializable hs = (HeightSerializable) data							.getSerializableExtra(seralizableKey);					TextView textView4 = (TextView) findViewById(R.id.text4);					textView4.setText("性别:" + hs.getSex() + "\n标准体重:"							+ hs.getWeight());				} catch (Exception e) {					e.printStackTrace();				}			}		}	}}


EX03_10_1.java
import java.text.DecimalFormat;import java.text.NumberFormat;import android.app.Activity;import android.content.Intent;import android.os.Bundle;import android.util.Log;import android.widget.TextView;public class EX03_10_1 extends Activity {	private static final String TAG = "EX03_10_1";	@Override	public void onCreate(Bundle savedInstanceState) {		super.onCreate(savedInstanceState);		setContentView(R.layout.myalyout);		WeightParcelable wp = (WeightParcelable) getIntent()				.getParcelableExtra(EX03_10.parcelableKey);		String sex = wp.getSex();		double height = wp.getHeight();		String sexText = "";		if (sex.equals("M")) {			sexText = "男性";		} else {			sexText = "女性";		}		String weight = this.getWeight(sex, height);		TextView tv1 = (TextView) findViewById(R.id.text1);		tv1.setText("性别:" + sexText + "\n身高:" + height + "厘米\n标准体重: " + weight				+ "公斤");		// 返回对象		Intent data = new Intent();		HeightSerializable hs = new HeightSerializable();		hs.setSex(sexText);		hs.setWeight(Double.valueOf(weight));		data.putExtra(EX03_10.seralizableKey, hs);//从这里返回对象		setResult(RESULT_OK, data);	}	private String format(double num) {		NumberFormat formatter = new DecimalFormat("0.00");		String s = formatter.format(num);		return s;	}	private String getWeight(String sex, double height) {		String weight = "";		if (sex.equals("M")) {			weight = format((height - 80) * 0.7);		} else {			weight = format((height - 70) * 0.6);		}		return weight;	}}
1 楼 windloverain 2010-12-01  
不错,学习了,一会试试。
2 楼 whao189 2011-05-19  
我有个问题。。想 请教一下。。

是这样的

@Override 
    public void writeToParcel(Parcel out, int flags) {  
        out.writeString(sex);  
        out.writeDouble(height);  
    }  

private WeightParcelable(Parcel in) {  
        sex = in.readString();  
        height = in.readDouble();  
    }  


这个地方如果 sex height 的类型 都是一样 的 加入都是string 怎么 处理呢??

你在readString 的 时候 Parcel会帮你 自动的  比对数据么?

希望楼主能指点一二!
3 楼 GhostFromheaven 2011-05-21  
whao189 写道
我有个问题。。想 请教一下。。

是这样的

@Override 
    public void writeToParcel(Parcel out, int flags) {  
        out.writeString(sex);  
        out.writeDouble(height);  
    }  

private WeightParcelable(Parcel in) {  
        sex = in.readString();  
        height = in.readDouble();  
    }  


这个地方如果 sex height 的类型 都是一样 的 加入都是string 怎么 处理呢??

你在readString 的 时候 Parcel会帮你 自动的  比对数据么?

希望楼主能指点一二!


可以都加入String.其实它内部是用map实现的,是key-value对。
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