不同的activity传递自定义对象

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

Ruby代码



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();

}

}

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

Java代码



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;

}

}

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

Java代码



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();

}

}

}

}

}

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

Java代码



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;

}

}