setValue()与&的区别MutableLiveData中的postValue() [英] Difference of setValue() & postValue() in MutableLiveData

问题描述

有两种方法可以更改MutableLiveData的值.但是 setValue() 和& MutableLiveData中的 postValue() .

There are two ways that make change value of MutableLiveData. But what is difference between setValue() & postValue() in MutableLiveData.

我找不到相同的文档.

这是Android的类MutableLiveData.

Here is class MutableLiveData of Android.

package android.arch.lifecycle;

/**
 * {@link LiveData} which publicly exposes {@link #setValue(T)} and {@link #postValue(T)} method.
 *
 * @param <T> The type of data hold by this instance
 */
@SuppressWarnings("WeakerAccess")
public class MutableLiveData<T> extends LiveData<T> {
    @Override
    public void postValue(T value) {
        super.postValue(value);
    }

    @Override
    public void setValue(T value) {
        super.setValue(value);
    }
}

推荐答案

基于文档:

setValue():

设置值.如果有活动的观察者，则该值为 派给他们.必须从主线程调用此方法.

Sets the value. If there are active observers, the value will be dispatched to them. This method must be called from the main thread.

postValue():

将任务发布到主线程以设置给定值.如果您在主线程执行发布的任务之前多次调用此方法，则只会分派最后一个值.

Posts a task to a main thread to set the given value. If you called this method multiple times before a main thread executed a posted task, only the last value would be dispatched.

总而言之，关键区别在于:

To summarize, the key difference would be:

setValue()方法必须从主线程调用.但是，如果需要从后台线程设置值，则应使用postValue().

setValue() method must be called from the main thread. But if you need set a value from a background thread, postValue() should be used.

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