Android——ViewModel需要有参构造报错

桂？2024-06-26 20:07

bash 复制代码

Process: com.wyg.util, PID: 32767
java.lang.RuntimeException: Cannot create an instance of class com.wyg.xc.XCViewModel                                                                                            
at androidx.lifecycle.ViewModelProvider$NewInstanceFactory.create(ViewModelProvider.kt:204)

原因是自己ViewModel继承类的构造

java 复制代码

public XCViewModel(String name) {
	this.name=name
}

解决方法

新建Factory类实现ViewModelProvider.Factory

java 复制代码

public class XCViewModelFactory implements ViewModelProvider.Factory {
    private String name;

    public XCViewModelFactory(String name) {
        this.name = name;
    }

    @NonNull
    @Override
    public <T extends ViewModel> T create(@NonNull Class<T> modelClass) {
        if (modelClass.isAssignableFrom(XCViewModel.class)) {
            return (T) new XCViewModel(name);
        }
        throw new IllegalArgumentException("Unknown ViewModel class");
    }
}

最后在Fragment继承类或Activity中使用

java 复制代码

    @Override
    public void onViewCreated(@NonNull View view, @Nullable Bundle savedInstanceState) {
    	String name="张三";
        XCViewModelFactory factory = new XCViewModelFactory(name);
        xcViewModel = new ViewModelProvider(this, factory).get(XCViewModel.class);
        }