android——Intent傳值

在這裏介紹4種：
1.簡單傳值
直接利用putExtra()
在ActivityA：

Intent intent = new Intent(Main8Activity.this,MainActivityB.class);
String s = et_text.getText().toString();
intent.putExtra("string",s);
intent.putExtra("age",22);
startActivity(intent);

在ActivityB：

Intent intent = getIntent();
String s = intent.getStringExtra("string");
int age = intent.getIntExtra("age",0);

2.利用Bundle
在ActivityA：

Intent intent = new Intent(Main8Activity.this,MainActivityB.class);

//數據封裝，第一種利用Bundle
Bundle bundle = new Bundle();
String s = et_text.getText().toString();
bundle.putString("string",s);
//把Bundle存入Intent
intent.putExtra("data",bundle);
startActivity(intent);

在ActivityB：

Intent intent = getIntent();

//把Bundle裏的數據取出,第一種
Bundle bundle = intent.getBundleExtra("data");
String s = bundle.getString("string");

3.傳遞對象，利用Serializable
先建一個類Cat

package com.example.john.test1;

import java.io.Serializable;


public class Cat implements Serializable{
    String name;
    int age;
    String kind;

    @Override
    public String toString() {
        return "Cat{" +
                "name='" + name + '\'' +
                ", age=" + age +
                ", kind='" + kind + '\'' +
                '}';
    }
}

在ActivityA：

Cat cat = new Cat();
                cat.name = "name";
                cat.age = 22;
                cat.kind = "kind";

                Intent intent1 = new Intent(this,MainActivityB.class);
                intent1.putExtra("cat",cat);
                startActivity(intent1);

在ActivityB：

//獲取對象裏的信息
Cat cat = (Cat)intent.getSerializableExtra("cat");
textView.setText(cat.toString());

4.傳遞對象，利用Parcelable，這個比序列化的性能更高，雖然代碼複雜一點
先建一個類Dog

package com.example.john.test1;

import android.os.Parcel;
import android.os.Parcelable;

/**
 * Created by john on 2017/4/10.
 */

public class Dog implements Parcelable{
    String name;
    int age;
    String kind;

    @Override
    public String toString() {
        return "Dog{" +
                "name='" + name + '\'' +
                ", age=" + age +
                ", kind='" + kind + '\'' +
                '}';
    }
    //描述內容
    @Override
    public int describeContents() {
        return 0;
    }
    //把要傳遞的內容寫到包裹中去
    @Override
    public void writeToParcel(Parcel dest, int flags) {
        dest.writeString(name);
        dest.writeInt(age);
        dest.writeString(kind);
    }
    //對象的創建器
    public static final Parcelable.Creator<Dog> CREATOR
            = new Parcelable.Creator<Dog>(){

        @Override
        public Dog createFromParcel(Parcel in) {
            Dog dog = new Dog();
            dog.name = in.readString();
            dog.age = in.readInt();
            dog.kind = in.readString();
            return dog;
        }

        @Override
        public Dog[] newArray(int size) {
            return new Dog[size];
        }
    };
}

在ActivityA：

Dog dog = new Dog();
                dog.name = "dog";
                dog.age = 12;
                dog.kind = "狗";

                Intent intent2 = new Intent(this, MainActivityB.class);
                intent2.putExtra("dog",dog);
                startActivity(intent2);

在ActivityB：

Dog dog = (Dog)intent.getParcelableExtra("dog");
        textView.setText(dog.toString());