（Android/Java）如何分配字符串并跨活动或Java类共享？

比如说，我只有一个按钮。使用如下XML：

你有两种方法：

要使用Intent.putetrastring键，请输入字符串值 使用单例传递对象、字符串甚至自定义类 示例： 例1

 Intent intent =  new Intent(TeamAOffense.this, ExchangeAToB.class);
 intent.putExtra("KEY", "Value");
 startActivity(intent);
 // and in `ExchangeAToB` class use 
 String key getIntent().getExtras().getString("KEY");`

例2

public class MyInstance{
private static MyInstance instance = null;
private Object mObject;
private MyInstance(){
mObject = new Object();
}

public static MyInstance getInstance(){
if(instance == null){
instance = new MyInstance();
}
return instance;
}

public Object getObject(){
return mObject;
}

public void setObject(Object obj){
mObject = obj;
}
}
// Use MyInstance.getInstance().setObject(new String()); // in activity 1
// and Object myObject = MyInstance.getInstance().getObject(); // in activity 2

**使用后别忘了清理物品

 Intent intent =  new Intent(TeamAOffense.this, ExchangeAToB.class);
 intent.putExtra("KEY", "Value");
 startActivity(intent);
 // and in `ExchangeAToB` class use 
 String key getIntent().getExtras().getString("KEY");`

public class MyInstance{
private static MyInstance instance = null;
private Object mObject;
private MyInstance(){
mObject = new Object();
}

public static MyInstance getInstance(){
if(instance == null){
instance = new MyInstance();
}
return instance;
}

public Object getObject(){
return mObject;
}

public void setObject(Object obj){
mObject = obj;
}
}
// Use MyInstance.getInstance().setObject(new String()); // in activity 1
// and Object myObject = MyInstance.getInstance().getObject(); // in activity 2